Earlier this month, NASA’s TESS space telescope successfully captured the faint glow and tail of an interstellar comet, further enriching its archive with observations that may provide critical insights into this unique celestial visitor from beyond our solar system.
This 3I/ATLAS image was captured by NASA’s TESS satellite on January 15, 2026. Image credit: NASA/Daniel Muthukrishna, MIT.
The interstellar comet 3I/ATLAS was discovered on July 1, 2025, by the NASA-funded ATLAS survey telescope in Rio Hurtado, Chile.
Known as C/2025 N1 (ATLAS) and A11pl3Z, this comet originated from the Sagittarius constellation.
3I/ATLAS holds the record for the most dynamically extreme orbit of any object tracked in our solar system.
It reached its closest approach to the Sun, or perihelion, on October 30, 2025.
The comet passed within 1.4 astronomical units (approximately 210 million km) of our Sun, just crossing Mars’ orbit.
After its brief obscuration behind the Sun, it reemerged near the triple star system Zania, located in the Virgo constellation.
According to MIT astronomer Daniel Muthukrishna and his team, “The TESS spacecraft systematically scans vast areas of the sky for about a month, looking for variations in light from distant stars to identify orbiting exoplanets and new worlds beyond our solar system.”
“Additionally, this technology enables TESS to detect and monitor remote comets and asteroids,” they added.
Notably, 3I/ATLAS had been observed prior to its official discovery in May 2025. For more details, you can read the findings.
From January 15 to 22, 2026, TESS re-observed the interstellar comet during a dedicated observation period.
The comet’s brightness measured approximately 11.5 times the apparent magnitude, making it about 100 times dimmer than what the human eye can perceive.
By revisiting the TESS data, astronomers successfully identified this faint comet by stacking multiple observations to track its motion, showcasing the extraordinary capabilities of the TESS mission.
Astronomers utilizing ESA’s XMM-Newton Observatory have captured X-ray images of 3I/ATLAS, the third confirmed interstellar object to traverse our solar system, following 1I/Oumuamua and 2I/Borisov.
This XMM-Newton image displays an X-ray visualization of the interstellar comet 3I/ATLAS. The center features a bright red dot against a dark backdrop, resembling a burning lighthouse. Surrounding this core is a soft gradient of purple and blue, forming a slightly rotated rectangular frame divided by a thin horizontal line, indicating the detector gap. Red represents low-energy X-rays, while blue signifies regions with minimal X-rays. Image credit: ESA / XMM-Newton / C. Lisse / S. Cabot / XMM ISO Team.
On December 3, 2025, XMM-Newton tracked the interstellar comet 3I/ATLAS for approximately 20 hours.
During this observation, the interstellar object was about 282-285 million kilometers away from the spacecraft.
XMM-Newton utilized the European Photon Imaging Camera (EPIC)-PN, its most sensitive X-ray camera, to observe the comet.
“This XMM-Newton image highlights the comet radiating in low-energy X-rays. The blue regions indicate voids with nearly no X-rays, while the red areas showcase the comet’s X-ray emissions,” stated members of the XMM-Newton team.
Astronomers anticipated this glow, as gas molecules emitted from comets generate X-rays upon colliding with the solar wind.
“These X-rays can originate from the interaction of the solar wind with gases such as water vapor, carbon dioxide, and carbon monoxide, and have previously been detected by telescopes like NASA/ESA/CSA’s James Webb Space Telescope and NASA’s SPHEREx,” added the researchers.
“However, these telescopes possess distinct sensitivities to gases like hydrogen and nitrogen.”
“They are almost undetectable by optical and ultraviolet instruments, such as the NASA/ESA Hubble Space Telescope and ESA’s JUICE camera.”
“This makes X-ray observation an exceptional resource,” they emphasized.
“Researchers will be able to identify and examine gases that are difficult to detect with alternative instruments.”
“Multiple scientific groups suggest that the first observed interstellar object, 1I/’Oumuamua, may have been composed of unusual ices like nitrogen and hydrogen.”
“Although 1I/Oumuamua is currently too distant to study, 3I/ATLAS provides fresh opportunities to investigate interstellar bodies. X-ray observations will supplement other data and assist scientists in understanding the composition of these objects.”
The Hubble team has unveiled breathtaking new images of interstellar comet 3I/ATLAS captured by the NASA/ESA Hubble Space Telescope. This marks only the third instance of such a comet being observed.
This image of interstellar comet 3I/ATLAS was captured by Hubble on November 30, 2025. At that time, the comet was around 286 million kilometers (178 million miles) from Earth. Image credits: NASA / ESA / STScI / D. Jewitt, UCLA / M.-T. Hui, Shanghai Observatory / J. DePasquale, STScI.
Discovered on July 1, 2025, by the NASA-funded ATLAS (Asteroid Terrestrial Impact Last Alert System) survey telescope in Rio Hurtado, Chile, 3I/ATLAS is a remarkable interstellar comet.
At the time of its discovery, the comet had a heliocentric distance of 4.51 astronomical units (AU) and an eccentricity of 6.13.
This object, also referred to as C/2025 N1 (ATLAS) and A11pl3Z, approaches from the direction of the constellation Sagittarius, traveling at an impressive radial velocity of about 58 km (36 miles) per second.
3I/ATLAS passed near Mars at a distance of 0.194 AU on October 3 and reached its closest encounter with the Sun, known as perihelion, on October 30.
On March 16, 2026, this interstellar visitor will approach Jupiter at a distance of 0.357 astronomical units.
“Hubble tracked a comet across the sky,” they stated.
“As a result, the background stars appear as streaks of light.”
“Hubble had previously observed 3I/ATLAS in July, shortly after its discovery, and several NASA missions have also studied the comet since then.”
“Observations are expected to persist for several more months as 3I/ATLAS journeys out of the solar system.”
“This image displays a teardrop-shaped glowing halo extending toward the sun,” stated Harvard University Professor Avi Loeb about the new Hubble images.
“This extension of the tail toward the sun was also noticeable in the pre-perihelion Hubble images taken on July 21, where 3I/ATLAS was approaching the Sun from a distance 56% greater than that of Earth.”
“The new radius of the glow is estimated to be around 40,000 km (24,855 miles), with its retro tail extension reaching approximately 60,000 km (37,282 miles).”
“In recent papers, I suggested that the coma teardrops in the 3I/ATLAS post-perihelion images are linked to numerous macroscopic non-volatile objects that have separated from the Sun due to measurements of non-gravitational accelerations moving away from the Sun,” he elaborated.
“I predicted that if the object overlapped with 3I/ATLAS at perihelion, by November 30th, the swarm would be about 60,000 km closer to the Sun than 3I/ATLAS.”
“This separation aligns perfectly with the teardrop-shaped anti-caudal extension visible in the new Hubble image.”
NASA’s Psyche spacecraft has obtained fresh images of 3I/ATLAS, marking it as the third astronomical object and the second comet observed from outside our solar system.
Psyche secured four observations of 3I/ATLAS over an 8-hour period on September 8 and 9, 2025. Image credit: NASA/JPL-Caltech/ASU.
3I/ATLAS was found on July 1, 2025, by the ATLAS survey telescope located in Rio Hurtado, Chile.
The orbits of interstellar comets represent the most dynamically extreme pathways of any astronomical object recorded within our solar system.
Known also as C/2025 N1 (ATLAS) and A11pl3Z, 3I/ATLAS reached its closest point to the Sun on October 30, 2025.
The latest images of the comet were captured during an eight-hour window on September 8 and 9, 2025, when 3I/ATLAS was roughly 53 million kilometers (33 million miles) away from NASA’s Psyche spacecraft.
“The observations collected by the mission’s multispectral imager will assist in refining the trajectory of 3I/ATLAS,” stated members of the Psyche team.
“Psyche’s multispectral imager consists of a pair of identical cameras fitted with filters and telephoto lenses to photograph the surface of the metal-rich asteroid Psyche across various wavelengths of light.”
“During these observations, Comet 3I/ATLAS was moving away from the spacecraft, but the imager’s sensitivity to the comet’s reflected sunlight allowed for accurate tracking of the object.”
The recent observations further illuminate the faint coma—a cloud of gas and dust—surrounding 3I/ATLAS’ core, which is a frozen mixture of ice and rock.
“Psyche will collaborate with numerous other NASA missions to track the positions of comets over time, aiding astronomers in comprehending the movement of such objects within our solar system,” researchers stated.
“Though comets do not pose a direct threat to Earth, NASA’s space missions contribute to ongoing efforts to discover, monitor, and better understand objects in our Solar System.”
NASA’s STEREO (Solar-Earth Relations Observatory), the NASA/ESA SOHO (Solar-Heliospheric Observatory), and NASA’s PUNCH (Corona-Heliosphere Integrating Polarimeter) missions had the extraordinary capability to observe sky regions near the Sun, enabling them to monitor 3I/ATLAS as it traversed behind the Sun from Earth’s perspective.
3I/ATLAS moves at an incredible speed of 209,000 km (130,000 miles) per hour, visualized through a series of colorized stacked images captured from September 11 to 25, 2025, using the Heliocentric Imager-1 instrument aboard NASA’s STEREO-A spacecraft. Image credit: NASA / Lowell Observatory / Qicheng Zhang.
STEREO monitored the interstellar comet 3I/ATLAS between September 11 and October 2, 2025.
The mission aims to examine solar activity and its effects on the entire solar system and is part of a collection of NASA spacecraft studying comets, offering insights on their size, physical characteristics, and chemical makeup.
Initially, it was believed that comet 3I/ATLAS would be too dim for STEREO’s instruments, but advanced image processing using the visible-light telescope Heliospheric Imager-1 and the stacking of images revealed 3I/ATLAS effectively.
By overlaying multiple exposures, distinct images were produced, showing the comet slightly brighter at the center.
This image of 3I/ATLAS combines observations from the NASA/ESA SOHO mission between October 15 and 26, 2025. Image credit: NASA / ESA / Lowell Observatory / Qicheng Zhang.
The SOHO spacecraft managed to catch a glimpse of 3I/ATLAS from October 15 to 26, 2025.
During this time frame, the LASCO instrument suite onboard SOHO identified comets crossing its observation area from around 358 million km (222 million miles) away, which is more than twice Earth’s distance from the Sun.
SOHO orbits at Sun-Earth Lagrange Point 1, a gravitational equilibrium point approximately 1.6 million km (1 million miles) closer to the Sun along the Sun-Earth axis.
Members of the SOHO team also utilized stacking techniques to create images of 3I/ATLAS.
In this image, 3I/ATLAS is clearly visible as a bright object in the center, created by consolidating observations from NASA’s PUNCH mission conducted from September 20 to October 3, 2025. Image credit: NASA/Southwest Research Institute.
The PUNCH mission observed 3I/ATLAS from September 20 to October 3, 2025.
These observations indicated that the comet’s tail extended slightly to the lower right.
During this period, the comet was so dim that the PUNCH team was uncertain if the spacecraft would be able to detect it well, given its primary focus on studying the Sun’s atmosphere and solar wind rather than comets.
However, by collecting multiple observations, 3I/ATLAS and its tail became distinctly visible.
“We’re truly pushing the limits of this system,” stated Dr. Kevin Walsh, a planetary scientist at the Southwest Research Institute who led the PUNCH observations of comets.
This image of 3I/ATLAS was captured by the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter on October 2, 2025. Credit: NASA / JPL-Caltech / University of Arizona.
On October 2, 2025, the Mars Reconnaissance Orbiter (MRO) observed 3I/ATLAS from approximately 30 million km (19 million miles) away.
The MRO team utilized the High-Resolution Imaging Science Experiment (HiRISE), which typically focuses on the Martian surface.
By maneuvering, the spacecraft can direct its camera toward other celestial objects. This method was previously employed in 2014 when HiRISE collaborated with MAVEN to examine the comet Siding Spring.
“Observations of interstellar objects are still infrequent, so each time we learn something new,” noted Dr. Shane Byrne, HiRISE principal investigator and researcher at the University of Arizona.
“We were fortunate that 3I/ATLAS came close to Mars.”
Captured at a resolution of about 30 km (19 miles) per pixel, 3I/ATLAS appears as a pixelated white sphere in the HiRISE images.
“This sphere is a cloud of dust and ice, referred to as a coma, that the comet emits as it travels past Mars,” the researchers added.
Further analysis of HiRISE images could assist scientists in establishing an upper limit on the size of a comet’s core, composed of ice and dust.
The images might also uncover properties of particles known as comas within the comet’s atmosphere.
Ongoing scrutiny of the images may reveal nuclear fragments and gas jets expelled as comets disintegrate over time.
“One of MRO’s greatest contributions to NASA’s Mars research is its ability to observe surface phenomena that only HiRISE can detect,” explained Dr. Leslie Tampali, MRO’s project scientist and a research scientist at NASA’s Jet Propulsion Laboratory.
“This opportunity allows us to study passing space objects.”
“Thanks to NASA’s versatile fleet of spacecraft throughout our solar system, we can continue to observe this dynamic entity from unique perspectives,” stated Georgia Tech researcher Professor James Ray, a HiRISE co-investigator.
“All three prior interstellar objects exhibit significant differences from one another and from typical Solar System comets, making every new observation incredibly valuable.”
“Being able to observe a visitor from another star system is extraordinary in itself,” remarked Dr. Tomás Díaz de la Rubia, senior vice president for research and partnerships at the University of Arizona.
“Doing so from a University of Arizona-led instrument orbiting Mars adds to its remarkable nature.”
“This moment highlights the ingenuity of our scientists and the lasting impact of this university’s leadership in space exploration.”
“HiRISE exemplifies how discovery tools can benefit both science and the public interest.”
NASA unveiled new images of an interstellar comet on Wednesday, marking it as the third confirmed visitor from elsewhere in the galaxy. The visuals depict the comet as a luminous point encircled by a halo of gas and dust.
In the eagerly awaited photograph, the comet, designated 3I/ATLAS, mainly appears as an illuminated spot, though its tail can be seen as a faint elongated streak in some frames.
Interstellar comet 3I/ATLAS (highlighted in the center) as captured by NASA’s Lucy spacecraft. This image was formed by combining multiple photos taken on September 16, as the comet approached Mars. NASA / Goddard / SwRI / JHU-APL
First identified in July, comet 3I/ATLAS has generated significant excitement among scientists and astronomy enthusiasts. The fascination arises from the unique chance to observe interstellar objects at such proximity.
The latest images were captured by an array of NASA spacecraft while the enigmatic comet circled through the inner solar system from late September to mid-October. The release was delayed due to a government shutdown that interrupted operations at NASA and other federal institutions.
The NASA missions responsible for these new images include the PUNCH satellite, which observes the Sun, the Solar Heliosphere Observatory, the MAVEN mission studying Mars’ atmosphere, and the Perseverance rover, currently on Mars’ surface.
Traveling at 130,000 miles per hour, the comet 3I/ATLAS was depicted in a series of colorized stacked visuals from September 11 to 25 using the STEREO-A (Solar Terrestrial Relations Observatory) visible-light camera. NASA / Lowell Observatory / Zhang Qicheng
Prior to 3I/ATLAS, the only confirmed interstellar objects to have entered our solar system were the cigar-shaped ‘Oumuamua in 2017 and comet 2I/Borisov in 2019.
The arrival of 3I/ATLAS in our cosmic vicinity has sparked wild speculations about the possibility of it being extraterrestrial technology or an alien spacecraft, although no scientific backing supports these ideas. NASA officials stated in a press conference on Wednesday that all current observations align with known comet characteristics.
“We certainly haven’t detected any technosignatures or anything that would suggest it is anything but a comet,” remarked Nicki Fox, associate administrator for NASA’s Science Mission Directorate.
Nonetheless, the comet’s interstellar roots indicate it possesses intriguing attributes that could yield new insights regarding star systems beyond our own, according to Fox.
“That difference is particularly fascinating to us,” she stated. “It may have existed before our solar system was formed. That’s pretty exciting.”
In the forthcoming weeks, scientists will have enhanced opportunities to study 3I/ATLAS and further analyze its appearance, speed, chemical makeup, and potential origins.
“This is a new scientific chance and an opportunity to delve into the composition and history of other solar systems,” expressed Tom Statler, NASA’s lead scientist for small solar system bodies. “We’re just beginning to understand these types of objects and determining the right questions to pose about them.”
Comet 3I/ATLAS was documented by the PUNCH satellite in low Earth orbit from September 28 to October 10, when it was between 231 to 235 million miles away. NASA/Southwest Research Institute
However, tracing the comet’s origin remains challenging, Statler noted.
3I/ATLAS came closest to the Sun at the end of October and is currently continuing its path through the inner solar system. It has been so near to the Sun that it has not been visible to terrestrial telescopes recently, but NASA anticipates it will become visible again post-December.
On December 19, 3I/ATLAS is expected to make a close pass by Earth. Although it poses no threat, NASA states that the comet will remain about 170 million miles away during this encounter.
Statler indicated that the James Webb Space Telescope will observe the comet in December, while ground-based telescopes like the W.M. Keck Observatory in Hawaii are also scheduled to capture images of the comet in the future.
An image depicting interstellar comet 3I/ATLAS as it approached Mars, captured by the European Space Agency’s ExoMars Trace Gas Orbiter. European Space Agency
The photos released by NASA on Wednesday join a growing collection acquired by various spacecraft across the solar system. In early October, the European Space Agency shared 3I/ATLAS images taken by the ExoMars Trace Gas Orbiter, which showed a bright point moving through the vastness of space.
This spacecraft, co-managed by the ESA and the Russian Federal Space Agency, detected a comet approaching near Mars at that time, about 18.6 million miles away according to ESA.
NASA continues to analyze additional data gathered by the fleet of spacecraft since early October.
“There’s much more to come,” Statler remarked. “Not all data has been transmitted through NASA’s Deep Space Network yet, and there are numerous observations still planned.”
Recent observations of 3I/ATLAS, the third interstellar object confirmed to traverse the solar system following 1I/Oumuamua and 2I/Borisov, reveal a sophisticated multi-jet configuration.
The image of 3I/ATLAS was captured by Lowell Observatory astronomer Qicheng Zhang on October 31, 2025. Image credit: Qicheng Zhang / Lowell Observatory.
Discovered on July 1, 2025, by the NASA-funded ATLAS (Asteroid Terrestrial Impact Last Alert System) survey telescope in Rio Hurtado, Chile, 3I/ATLAS is also referred to as C/2025 N1 (ATLAS) and A11pl3Z.
Originating from the direction of the Sagittarius constellation, this comet holds the designation of being the most dynamically extreme object recorded, characterized by its hyperbolic orbit with high eccentricity and extreme hyperbolic velocity.
3I/ATLAS came closest to the Sun, reaching perihelion, on October 30, 2025.
This interstellar visitor approached within 1.4 AU (astronomical units), or approximately 210 million km, of the Sun, which is just inside Mars’ orbit.
At perihelion, the comet traveled at a remarkable speed of about 68 km/s, and its proximity to the Sun temporarily rendered it invisible to Earth’s telescopes.
Following perihelion, it will once again be observable through telescopes until December as it gradually distances itself from both the Sun and Earth, returning to interstellar space.
The initial post-perihelion optical image of 3I/ATLAS (as shown above) was captured. This was announced on October 31 by astronomer Zhang Qicheng of Lowell Observatory using the Discovery Telescope.
This image of 3I/ATLAS was taken on November 8, 2025 by astronomers from the ICQ Comet Observation Group. Image credit: M. Jaeger / G. Lehmann / E. Prosperi.
On November 8th, three astronomers from the ICQ Comet Observation Group observed the comet situated 29 degrees from the Sun in the sky.
The images they captured depict a complex jet structure with at least seven jets, including several anti-tail planes.
“Given the multitude of jets emerging in various directions, the noted non-gravitational acceleration of 3I/ATLAS implies that more than 10 to 20 percent of its initial mass would need to be ejected near perihelion,” remarked Professor Avi Loeb of Harvard University discussing the ICQ images. He stated,
“Only a small fraction of this mass carries the necessary momentum in the favored direction.”
“Consequently, the debris cloud enveloping 3I/ATLAS likely constitutes a considerable portion of the comet’s original mass.”
This 3I/ATLAS image was taken on November 9, 2025, by astronomers from the British Astronomical Society. Image credit: Michael Buechner / Frank Niebling.
On November 9th, two astronomers from the British Astronomical Association (BAA) studied the comet using two telescopes.
Their combined image displayed a long “smoking” tail along with two anti-tail jets.
“3I/ATLAS is expected to make its closest approach to Earth on December 19, 2025, making the multijet structure an intriguing target for future observations with the Hubble and Webb telescopes,” Professor Loeb mentioned discussing the BAA images. He noted.
The minimum distance to Earth will be 269 million km, roughly 100 times the extent of the jet structure illustrated in the image.
This striking image of 3I/ATLAS was taken by the International Gemini Observatory in Chile, revealing the comet’s coma formed of gas and dust.
Image Credit: International Gemini Observatory/NOIRLab/NSF/AURA/Shadow the Scientist
3I/ATLAS, an interstellar comet traversing our solar system, presents a challenge in determining its origin due to potential alterations from cosmic rays over billions of years that could have completely transformed its characteristics.
Initially detected in July, astronomers have begun to analyze its intriguing traits, including its coma, which features carbon dioxide levels at least 16 times greater than standard comets in our solar system, marking it as one of the most CO2-rich comets ever seen.
While some researchers theorized that this might indicate an unusual star system as the comet’s birthplace (or, less plausibly, a link to extraterrestrial life), a more straightforward explanation has emerged.
Roman Maggiolo and colleagues from the Belgian Royal Institute for Astronautics and Aeronautics assert that the elevated CO2 concentrations are likely a result of significant alterations to the outer layers of 3I/ATLAS over billions of years due to cosmic rays.
“This slow process has often been neglected or underestimated, yet it profoundly impacts objects like comets and interstellar bodies,” Maggiolo states.
The team compared their findings from 3I/ATLAS to lab experiments that simulate cosmic ray bombardment of ice composed of water and carbon monoxide, akin to that found on comets. These experiments revealed that this process generates substantial CO2 and leaves behind a carbon-rich residue that aligns with observations from the comet.
“Gradually, cosmic rays create reactive radicals—molecular fragments that break down and reform, thereby altering the ice’s chemical makeup,” Maggiolo explains.
This revelation poses a setback for comprehending the origins of comets, as cosmic rays can obliterate critical evidence. Previously, astronomers thought interstellar comets like 3I/ATLAS were remarkably preserved, acting as cold fossils with vital data about other star systems; however, a more cautious approach may now be necessary concerning the insights they can provide.
Although its swift passage through the solar system limits the chances for satellites to explore and directly sample these comets, there remains a sliver of hope for clarifying the true nature of 3I/ATLAS.
Currently, the comet is nearing the Sun and isn’t visible from Earth but is anticipated to resurface in December. This close encounter might result in sufficient melting of the outer ice layer to unveil materials shielded from cosmic rays, as noted by Maggiolo. However, this is contingent upon how much ice has already vanished since its entry into the solar system and the thickness of the icy crust, details that are still unclear.
Cyriel Opitum, a professor at the University of Edinburgh in the UK, emphasizes that forthcoming observations utilizing both the James Webb Space Telescope and ground-based telescopes will be essential in uncovering primitive material beneath the comet’s surface. “We are looking forward to an exciting few months ahead,” she states.
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Interstellar comet 3I/ATLAS captured by the Gemini South Telescope in Chile
International Gemini Observatory/NOIRLab/NSF/AURA/Shadow the Scientist; J. Miller & M. Rodriguez (International Gemini Observatory/NSF NOIRLab), TA President (University of Alaska Anchorage/NSF NOIRLab), M. Zamani (NSF NOIRLab)
The interstellar object 3I/ATLAS is acting oddly once more. This foreign visitor from another star is now obscured by the sun’s shadow, leading some to speculate about its secretive nature. The only likely explanation, they whisper, is that it’s an alien spacecraft.
This notion, however, is utterly baseless. It simply doesn’t hold up that a spacecraft would choose to stay hidden for just a few days while previously visible and likely to be so again. If this were actually a stealthy spacecraft, then the aliens piloting it would either be incredibly foolish or believe us to be.
How can we assert this? As an astronomer recently explained to me, if 3I/ATLAS is indeed a spacecraft, it’s doing a remarkable job of masquerading as a comet. This is what fuels the sensational discussions surrounding 3I/ATLAS (named after the eagle’s eye). planetary defense equipment (I first noticed it in July), which was both amusingly frustrating and clearly ridiculous. The evidence overwhelmingly indicates that it is a comet.
Let’s explore why. It possesses a coma, a shell of vaporized ice. It exhibits a luminous tail. Its trajectory can best be described as that of an icy projectile entering our solar system from beyond. So, why is it “hiding” behind the sun? It just reached perihelion, the closest point to our solar star in its voyage through our cosmic neighborhood. Every celestial voyager, from comets to asteroids, experiences perihelion. 3I/ATLAS happens to be behind the Sun, yet closest to it from Earth’s viewpoint.
There are certainly some intriguing aspects of 3I/ATLAS that excite astronomers. For instance, it contains a higher concentration of carbon dioxide ice compared to water ice. Nevertheless, it remains a comet, not a space probe. Some materials are composed of – hold on, aren’t those metals? Spaceships are built from metal! So, could 3I/ATLAS actually be a spacecraft? Absolutely not; we routinely observe metals in the rocky, icy cores of comets. In truth, numerous comet types exist in our solar system, many of which are indeed peculiar.
It was also somewhat unusual that at one point 3I/ATLAS had its dusty tail oriented toward the Sun instead of the opposite direction. Some speculated it was not the tail but rather a spacecraft’s exhaust plume attempting to decelerate. However, the issue is that 3I/ATLAS’s orbit is consistent with that of an interstellar comet; it’s not as if someone applied brakes to an interstellar probe. The unique orientation of its tail resulted from the specific icy, powdery particles released from its surface. This transient object would typically be pushed away from the sun by solar radiation pressure, but some of this comet’s material was so dense that it couldn’t be redirected and consequently rolled toward the sun.
3I/ATLAS is only the third interstellar object ever documented, so investigating its small population is likely to uncover some remarkable characteristics. ‘Oumuamua, the first identified interstellar visitor, was significantly stranger. Its shape was likely cigar-like, rapidly accelerating as it left the solar system. Yet even this oddity can be perfectly rationalized: it was a flashy comet-like entity. The next two interstellar objects, 2I/Borisov and 3I/ATLAS, also showcase interesting features. But to propose they are spacecraft rather than comets is equivalent to calling ice in the freezer a pineapple. You can certainly say that, but if you aim to convince me, you must present more substantial proof.
Many among us, myself included, eagerly anticipate the day we learn we’re not alone in the universe. Thus, it’s no wonder that people jump to the unfounded conclusion that 3I/ATLAS might signal that this long-awaited day has finally come. However, in an age rife with misinformation, to suggest, against overwhelming evidence, that this comet could be alien is not just misguided; it’s profoundly irresponsible.
The findings of 1I/Oumuamua, 2I/Borisov, and 3I/ATLAS have revealed a substantial number of interstellar objects in the cosmos. Their widespread presence suggests that such objects are also found in protoplanetary disks, essential sites for planet formation. In these disks, interstellar objects could potentially bypass the 1-meter (3.3-foot) barrier in the traditional model of planet formation, initiating the creation of giant exoplanets.
This colorized image was taken by the CaSSIS instrument aboard ESA’s Trace Gas Orbiter on October 3, 2025, and displays the interstellar comet 3I/ATLAS. Image credit: ESA/TGO/CaSSIS.
Interstellar objects, including asteroids and comets, are those that have been expelled from their original star systems and are now traversing interstellar space, occasionally intersecting with other star systems.
Since 2017, astronomers have identified three interstellar objects passing through our solar system: 1I/’Oumuamua, 2I/Borisov, and the latest, 3I/ATLAS.
“Nevertheless, interstellar objects may exert a more significant influence than it appears at first glance,” states Professor Susanne Falzner, an astronomer at Jülich National Park.
“Interstellar objects could potentially incite planet formation, particularly around high-mass stars.”
Planets are formed from dusty disks that surround young stars through a process known as accretion. This theory posits that smaller particles gradually coalesce into larger objects, culminating in the formation of planet-sized bodies.
However, researchers have faced challenges in explaining how accretion can create objects larger than a meter amidst the chaotic collisions of planet-forming disks surrounding young stars. In simulations, the rocks tend to either bounce off each other or break apart upon collision, rather than adhering together.
Interstellar objects might help circumvent this issue. The researchers’ model illustrates how the dust-laden disks surrounding young stars can gravitationally capture millions of interstellar objects akin to 1I/’Oumuamua, which is estimated to be around 100 meters (328 feet) long.
“Interstellar space will supply ready-made seeds for the next phase of planet formation,” said Professor Falzner.
If interstellar objects could act as seeds for planets, it would also resolve another enigma.
Gas giant planets like Jupiter are scarce around smaller and colder stars, referred to as M dwarfs, but are more frequently found around larger stars similar to the Sun.
However, the lifespan of a planet-forming disk around a Sun-like star lasts only about 2 million years before dissipating, complicating the formation of gas giant planets in such a brief time frame.
That said, if captured interstellar objects serve as seeds for accretion, the planet-forming process could hasten, allowing giant planets to form within the lifetime of the disk.
“The more massive a star is, the more effectively it can capture interstellar objects in its disk,” Professor Falzner explained.
“As a result, planet formation seeded with interstellar objects should proceed more efficiently around these stars, offering a rapid pathway to forming giant planets.”
“And their swift formation is precisely what we’ve observed.”
During its closest encounter with Mars on October 3, 2025, comet 3I/ATLAS was situated 30 million km from the ESA’s ExoMars Trace Gas Orbiter (TGO).
The image of interstellar comet 3I/ATLAS was taken on October 3, 2025, by the CaSSIS instrument aboard the ESA’s Trace Gas Orbiter. Image credit: ESA/TGO/CaSSIS.
TGO acquired new images of 3I/ATLAS utilizing the Color and Stereo Surface Imaging System (CaSSIS).
“This observation posed significant challenges for this instrument,” noted Dr. Nick Thomas, Principal Investigator of ESA’s CaSSIS instrument.
“3I/ATLAS appears as a slightly blurred white dot that descends toward the center of the image.”
“This point represents the nucleus of the comet, which comprises an icy, rocky core surrounded by a coma.”
“Due to the distance, CaSSIS couldn’t differentiate between a nuclear and a coma state.”
“The CaSSIS camera has an angular resolution of 11.36 microradians (equivalent to 2.34 arc seconds) per pixel,” explained Professor Avi Loeb from Harvard University.
“At a minimum distance of approximately 30 million km from 3I/ATLAS, this resolution translates to 340 km.”
“This pixel size is one to two orders of magnitude larger than the anticipated core diameters of 3I/ATLAS, which range from a minimum of 5 km to a maximum of 46 km.”
“Some of the expansion can be observed in CaSSIS images,” he mentioned.
“The passage of 3I/ATLAS across the Martian sky will be viewed by the Mars rover from an angle nearly perpendicular to the 3I/ATLAS-Sun axis, allowing for a side view of the glow surrounding 3I/ATLAS.”
“The width of the luminous glow around 3I/ATLAS in the CaSSIS image is approximately twice that of a bright star appearing as a background point source in the same image.”
“This span corresponds to a scale of 680 km, which is an order of magnitude smaller than the width seen in Hubble images.”
“Thus, it’s evident that CaSSIS only captures the brightest regions surrounding the core of 3I/ATLAS and cannot detect the low surface brightness envelope visible in Hubble images.”
From November 2 to 25, 2025, ESA’s Jupiter Icy Satellites probe will observe 3I/ATLAS with a range of instruments. Image credit: ESA.
“Our Mars rovers continue to contribute significantly to Mars science, and it’s always thrilling to see them respond to unforeseen scenarios like this,” remarked Dr. Colin Wilson, ESA’s Mars Express and ExoMars project scientist.
“We eagerly await the insights the data will reveal following further analysis.”
Next month, ESA researchers are set to observe 3I/ATLAS with the Jupiter Icy Satellite Orbiter (JUICE).
While JUICE will be located further from 3I/ATLAS than last week’s Mars rover, the rover will detect the comet shortly after its closest approach to the Sun, indicating heightened activity.
“Observation data for JUICE is anticipated to be received by February 2026,” they noted.
Astronomers have detected hydroxyl (OH) gas, a chemical indicator of water, from the interstellar object 3I/ATLAS using an ultraviolet/optical telescope on NASA’s Neil Gehrels Swift Observatory.
Stacked images of the interstellar comet 3I/ATLAS obtained with NASA’s Neil Gehrels Swift Observatory: the first was captured on July 31 and August 1, 2025 (visit 1, upper half), and the second was on August 19, 2025 (visit 2, lower half). Image credit: Xing et al., others, doi: 10.3847/2041-8213/ae08ab.
The identification of the third interstellar object, 3I/ATLAS, on July 1, 2025, initiated a comprehensive characterization effort globally.
Learning from prior discoveries of interstellar objects 1I/Oumuamua and 2I/Borisov, an observation campaign was implemented to swiftly measure its initial brightness, morphology, light curve, color, and optical and near-infrared spectra.
Given the apparent brightness and early extension of the coma, there was suspicion of a gas outburst, yet none was detected.
Investigating the early activity of interstellar objects is crucial for understanding their chemical and physical evolution as they approach the Sun, as this may signify the first notable heating during their extensive dynamic lifetimes.
“The discovery of water marks a significant step in our grasp of how interstellar comets evolve,” stated Dennis Bordewitz, an astronomer from Auburn University.
“For solar system comets, water serves as a baseline for scientists to gauge their total activity and track how sunlight stimulates the release of other gases.”
“This is the chemical standard against which all assessments of volatile ice in cometary cores are made.”
“Detecting the same signal in an interstellar object means we can for the first time position 3I/ATLAS on the same scale employed to study comets indigenous to our Solar System. This is a progress toward juxtaposing the chemistry of planetary systems throughout our Milky Way galaxy.”
“What’s fascinating about 3I/ATLAS is the location of this water activity.”
Swift noticed the hydroxyl groups when the comet was nearly three times further from the Sun than Earth (well beyond the area where water ice on the surface could easily sublimate), recording a water loss rate of approximately 40 kg per second. At such distances, most solar system comets remain inactive.
The robust ultraviolet signal from 3I/ATLAS implies there might be additional mechanisms at play. Possibly, sunlight is warming small ice particles expelled from the core, causing them to vaporize and contribute to the surrounding gas cloud.
Such extensive water sources have only been detected on a limited number of far-off comets, suggesting intricate layered ice that holds clues regarding their formation.
Every interstellar comet discovered to date has unveiled a distinct aspect of planetary chemistry beyond our Sun.
Collectively, these observations illustrate that the composition of comets and the volatile ice that constitutes them can vary considerably from one system to another.
These variations imply the diversity of planet-forming environments and how factors like temperature, radiation, and composition ultimately influence planetary formation and, in some instances, the materials that lead to life.
Capturing the ultraviolet signals from 3I/ATLAS was a technological achievement in itself.
Swift employs a compact 30 cm telescope, yet from its orbit above Earth’s atmosphere, it can detect wavelengths of ultraviolet light that are largely absorbed by the atmosphere.
Free from sky glare or air interference, Swift’s ultraviolet/optical telescope achieves the sensitivity comparable to that of ground-based telescopes with 4-meter apertures for these wavelengths.
Its rapid targeting abilities allowed astronomers to analyze comets just weeks after their discovery, well before they become too faint or too close to the Sun for space study.
“When we observe water from an interstellar comet or its subtle ultraviolet signature (OH), we are interpreting notes from another planetary system,” Bordewitz notes.
“This indicates that the components essential for life’s chemical processes are not exclusive to us.”
“All interstellar comets we’ve observed thus far have been unexpectedly intriguing,” remarked Dr. Zexy Shin, a postdoctoral fellow at Auburn University.
“‘Oumuamua was dry, Borisov was rich in carbon monoxide, and now Atlas is revealing water at a distance we didn’t anticipate.”
“Each of these cases is transforming our understanding of how planets and comets form around stars.”
A study detailing the survey findings was published on September 30th in Astrophysics Journal Letter.
_____
Zexy Shin et al. 2025. Water production rate of interstellar object 3I/ATLAS. APJL 991, L50; doi: 10.3847/2041-8213/ae08ab
The bright area represents the comet’s core, which consists of a dense mixture of ice, rock, and dust. Typically, the nucleus is enveloped in a cloud of gas and dust known as a coma.
Since being discovered in July, Comet 3i/Atlas has captivated both astronomers and space enthusiasts. There have been intriguing theories suggesting it could be alien technology or a spacecraft, though no scientific backing exists for these ideas.
The comet is not stationary.
Researchers tracking its trajectory project that the comet will make its closest approach to the sun around October 30, as its orbit navigates through the inner solar system in the following weeks.
NASA has stated that 3i/Atlas poses no risk to Earth, maintaining a distance of about 170 million miles during its pass.
However, its near pass of Mars provided a unique observational opportunity.
The ExoMars Trace Gas Orbiter, jointly run by the ESA and Russia’s Federal Space Agency, directed its cameras at the comet for approximately a week starting October 1, officials from ESA noted. At that point, 3i/Atlas was roughly 18.6 million miles from the spacecraft.
Despite this, the orbiter’s instruments are primarily designed for imaging the Martian surface rather than distant objects, as explained by Nick Thomas, principal investigator for the imaging system.
“This posed a significant challenge for our instruments,” he stated in a statement. “Comets are approximately 10,000 to 100,000 times less dense than typical targets.”
Other interstellar visitors to our solar system include Oumuamua in 2017 and 2i/Borisov in 2019.
ESA emphasized, “All celestial bodies in our solar system share a common origin, but interstellar comets are unique outsiders, providing insights into the formation of distant worlds.”
As 3i/Atlas travels through our solar system, astronomers are eager to analyze its size and physical characteristics. Earlier this year, it was visible through ground-based telescopes, but it’s currently too close to the sun for observation. It is expected to reappear on the opposite side of the sun by early December, according to NASA.
NASA is tracking 3i/Atlas with the Hubble Space Telescope and plans additional observations in the upcoming months. The James Webb Space Telescope, Spherex Space Observatory, Parker Solar Probe, and the Exoplanet Survey Satellite are among the instruments hoping to catch a glimpse of the comet.
A photo taken recently by the Saturday camera captured streaks of light, leading to speculation online that it could be Comet 3i/Atlas. However, NASA has not confirmed this, and their public information office is currently closed due to the government shutdown.
ESA’s Mars Express spacecraft did focus its camera on the comet as it passed, although further analysis will be required to distinguish interstellar objects from the gathered data.
Positioned at the core of the Milky Way galaxy, Sagittarius B2 is an immense molecular cloud of gas and dust, boasting around 3 million times the mass of the sun.
The Sagittarius B2 molecular cloud, where stars, gases, and cosmic dust shimmer in near-infrared light, as captured by Webb’s Nircam instruments. Image credits: NASA/ESA/CSA/STSCI/A. GINSBURG, University of Florida/N. Budaiyev, University of Florida/T. Yu, University of Florida/A. Pagan, STSCI.
The distance from Earth to Sagittarius B2 is roughly 27,000 light years, while it sits just 390 light years from the center of the Milky Way.
This is the largest and most active star-forming cloud within our galaxy, accounting for half of the stars birthed in the central region, even though it comprises merely 10% of the material required for star formation in that area.
“Sagittarius B2 is situated just hundreds of light years away from the supermassive black hole located at the galaxy’s center, right at the heart of star formation.”
“Webb’s infrared observations can penetrate some of the dense clouds present, uncovering young stars alongside the warm dust enveloping them.”
“Examining Webb’s findings aids in unraveling the long-standing enigma surrounding the star formation process and why Sagittarius B2 generates stars at a rate surpassing other galaxy centers.”
“Interestingly, one of the most striking elements of Webb’s imagery of Sagittarius B2 is the regions that remain dark.”
“These seemingly vacant areas of space are so tightly packed with gas and dust that even Webb cannot detect them.”
“These dense clouds are the progenitors of future stars and are too young to emit light themselves.”
Webb’s Miri (medium-infrared device) displays the Sagittarius B2 region in medium-red light, revealing bright warm dust. Image credits: NASA/ESA/CSA/STSCI/A. GINSBURG, University of Florida/N. Budaiyev, University of Florida/T. Yu, University of Florida/A. Pagan, STSCI.
With the high resolution and sensitivity of Webb’s Miri (mid-infrared device), this area has been uncovered in remarkable detail, showcasing luminous cosmic dust heated by a massive, young star.
The red area labeled Sagittarius B2 North (located to the right in these Webb images) is among the most molecularly abundant regions known, yet astronomers have never observed it with such clarity before.
The differentiation lies in the longer wavelengths produced, even within the infrared spectrum, and the contrast between images from Webb’s Miri and Nircam (near-infrared camera) makes it evident.
“The luminous gas and dust emerge dramatically in mid-red light, though everything except for the brightest stars vanishes from sight,” the astronomer noted.
“In contrast to Miri, vibrant stars take center stage in Webb’s Nircam images.”
“Further investigations into these stars will yield insights into their masses and ages, aiding astronomers in comprehending the intricacies of star formation within this dense, dynamic galactic core.”
“Has this activity persisted for millions of years? Or has an unknown process triggered it recently?”
“We anticipate that Webb will illuminate the reasons behind the disproportionate star formation centered around galaxies.”
“While there are ample gaseous components in this area, overall productivity is not on par with that of Sagittarius B2.”
“Sagittarius B2 contains only 10% of the galaxy-centric gas but is responsible for 50% of the stars.”
Following 1i/oumuamua and 2i/borisov, 3i/atlas is the third object and has been confirmed as the second comet originating from outside the solar system.
This image from the Gemini North Telescope Multi-Object Spectrometer (GMOS-N) depicts the interstellar comet 3i/Atlas. Image credits: International Gemini Observatory/Noirlab/NSF/Aura/K. Meech, Ifa&U. Hawaii / Jen Miller & Mahdi Zamani, Noirlab.
The comet 3i/Atlas was identified on July 1, 2025, by the Asteroid Land Impact Trastor Alt System (ATLAS), a project supported by NASA.
Also referred to as C/2025 N1 (ATLAS) and A11PL3Z, the comet is approaching from the direction of Sagittarius.
Its orbit is the most dynamically extreme among the objects documented within the solar system.
“While aliens may not be the first to engage with us, 3i/Atlas has much to teach us, as it is merely the third recorded interstellar entity to traverse our solar system,” stated Jacqueline McClary, an astronomer at Northeastern University.
“All comet-like interstellar bodies are unique in that they are the only ones that have provided us with physical observations coming from outside our solar system. They serve as messengers from afar.”
“Given how rare it is to detect interstellar objects within our solar system, each discovery is distinct,” remarked Adina Feinstein, an astronomer at Michigan State University.
“3i/Atlas presents an opportunity to examine other solar systems closely, without the necessity of traveling to them.”
From the moment 3i/Atlas was observed, it was evident that it deviated from typical comet behavior. Initially, it appeared to emit an unusual light.
Comets are generally very dark, which makes them challenging for astronomers to detect initially.
As they near the sun, solar radiation prompts volatile compounds and ice to sublimate from their surfaces.
This process leads to the formation of a coma, which ultimately evolves into the iconic tail associated with comets across the night sky.
“Jupiter is positioned 5 AU from the Sun, and most comets need to approach closer for solar radiation to generate enough intensity to form this melted tail,” Dr. McClary said.
“Comet 3I/Atlas developed its coma at a considerably greater distance than typical, remaining beyond Jupiter’s orbit.”
3i/Atlas began to emit light far from the sun, prompting initial speculation that it could be an extraterrestrial spacecraft. What else could emit light so rapidly?
However, later observations suggested that it not only possesses a comet-like tail but is also rich in carbon dioxide.
The NASA/ESA/CSA James Webb Space Telescope has ultimately unveiled that comets are remarkable for attributes beyond their interstellar heritage.
Not only was it composed primarily of carbon dioxide, but it also exhibited an extraordinary ratio of carbon dioxide ice to water ice, the best ever documented.
This discovery allows for insight into the conditions that prevail in other solar systems and how such systems were initially formed.
“Clearly, the parent system of 3i/Atlas may have had a wealth of carbon dioxide, or perhaps a unique radiative process occurred that led to the depletion of other materials, leaving abundant carbon dioxide,” Dr. McClary remarked.
“By understanding the composition of this comet and comparing it with other interstellar comets, we gain insight into solar system formation across different environments.”
The precise origin of 3i/atlas remains elusive.
“It likely hails from the Milky Way’s bulge, but pinpointing its exact source will be challenging,” Dr. McCleary commented.
“For it to have escaped its parent solar system, the comet must have undergone a gravitational disturbance that altered its trajectory, setting it on its current path into the solar system.”
Nevertheless, scientists have gained a more intricate understanding of the comet, having observed it crossing Jupiter’s orbit since October, elucidating more about its characteristics.
The Juno satellite orbiting Jupiter is ideally suited to observe these interstellar visitors.
“We may be able to observe this comet with remarkable clarity. It could prove particularly intriguing as it nears the sun, causing significant carbon dioxide vaporization, so we can assess what remains,” Dr. McClary stated.
Gaining more knowledge about 3i/Atlas assists not only in comprehending the nature of other solar systems, but also in exploring the conditions under which sentient life might arise, given the uniqueness of our solar system.
“This serves as a window into the primitive materials of other solar systems, which is invaluable for refining models of solar system formation,” Dr. McCullilia said.
“Is our solar system common or rare? It appears to be relatively uncommon, offering us a way to quantify its uniqueness.”
“Investigating other solar systems places humanity in a broader context,” Dr. Feinstein remarked.
“One of the most profound questions we face is, are we alone in the universe? Each NASA mission brings us a step closer to answering this monumental question.”
“Capturing numerous observations of these interstellar objects, especially as they approach the sun, is crucial for understanding their behaviors,” noted John Noonan, an astronomer at Auburn University.
“These interstellar objects may not have been significantly warmed in millions, if not billions, of years, making it fascinating to study how they react to early thermal exposure.”
Researchers at the Southwest Research Institute have completed a study outlining how the proposed spacecraft could fly by interstellar comets, offering valuable insights into properties of these bodies throughout the solar system. Leveraging recent findings from interstellar comet 3i/Atlas, they explored mission concepts and concluded that the proposed spacecraft could potentially intercept and observe 3i/Atlas.
Hubble captured this image of 3i/Atlas when it was 446 million km (277 million miles) from Earth on July 21, 2025. Image credits: NASA/ESA/David Jewitt, UCLA/Joseph Depasquale, Stsci.
In 2017, interstellar object 1i/’oumuamua became the first interstellar comet identified within the solar system.
Following that, the second interstellar comet, 2i/Borisov, was discovered in 2019, and recently, 3i/Atlas was identified this year.
“These novel types of objects present the first true opportunity for humanity to closely examine bodies formed in other star systems,” said Dr. Alan Stern, a planetary scientist at the Southwest Research Institute.
“Flybys of interstellar comets could yield unparalleled insight into their composition, structure, and characteristics, significantly enhancing our understanding of the solid body formation process in diverse star systems.”
Scientists estimate that numerous interstellar objects from distant origins cross Earth’s orbit each year, with up to 10,000 potentially entering Neptune’s orbit in certain seasons.
Dr. Stern and colleagues tackled unique design challenges while defining the costs and payload requirements for interstellar comet missions.
The hyperbolic trajectories and high velocities of these bodies present challenges for current avoidance methods, but this study indicated that Flybee reconnaissance is both feasible and cost-effective.
“The trajectory of 3i/Atlas falls within the intermittent range of missions we designed, and the scientific observations taken during such flybys would be groundbreaking,” stated Dr. Matthew Freeman from the Southwest Institute.
“The proposed mission would involve a rapid, frontal flyby, allowing us to gather substantial valuable data while also serving as a blueprint for future missions to other interstellar comets.”
The research establishes a significant scientific objective for its mission targeting interstellar comets.
Understanding the physical characteristics of a body sheds light on its formation and evolution.
Investigating the composition of interstellar comets may aid in explaining their origins and how evolutionary forces have shaped them since their inception.
Another objective is to thoroughly examine the coma of an object, the escaping atmosphere emanating from its center.
To devise mission orbital options, researchers created software to generate representative synthetic populations of interstellar comets, calculating the minimum energy trajectories from Earth to each comet’s pathway.
Software analyses have indicated that low-energy rendezvous trajectories are achievable, often requiring fewer resources during launch and flight compared to other solar system missions.
Scientists utilized the software to determine the trajectory the proposed spacecraft may have taken from Earth to intercept 3i/Atlas.
They found that the mission could potentially have reached 3i/Atlas.
“It’s incredibly promising regarding the emergence of 3i/Atlas,” noted Dr. Mark Tapley, an orbital mechanics expert at the Southwest Research Institute.
“We have demonstrated that there’s no need to launch any existing technology or mission frameworks that NASA has already employed to engage these interstellar comets.”
Astronomers utilized a Gemini Multi-Object Spectrometer (GMO) at the Gemini South Telescope, part of the NSF’s International Gemini Observatory in the Chilean Andes, to capture new multi-color images of the interstellar comet 3i/Atlas.
This image of 3i/Atlas was captured by the Gemini Multi-Object Spectrograph (GMO) on August 27, 2025 at the Gemini South Telescope. Image credit: International Gemini Observatory / NSF / AURA / Shadow The Scientist / J. Miller Array / M. M. Rodriguez, nsf/crask of rects Anchorage & Noirlab/M. Zamani, NSF’s Noirlab.
3i/Atlas was identified on July 1, 2025, by a NASA-supported Atlas (Asteroid Ground Shock Last Alert System) Survey Telescope in Riojartad, Chile.
The comet is anticipated to approach the Sun at a distance of 1.4 AU (210 million km, or 130 million miles) around October 30, 2025.
The latest images from Gemini/GMOS reveal a broad coma and tail extending roughly 1/120th of a degree across the sky, away from the Sun.
These features appear significantly more pronounced compared to earlier images of the comet, indicating that 3i/Atlas is becoming increasingly active as it traverses the inner solar system.
Recent observations also imply that the dust and ice from the comet closely resemble those of solar comets, suggesting a commonality in the processes that govern the formation of planetary systems around other stars.
“As 3i/Atlas journeys back into the depths of interstellar space, these images serve as both scientific milestones and enigmatic clues,” states Dr. Karen Meech, an astronomer from the Institute of Astronomy at the University of Hawaii.
“They remind us that our solar system is merely a fragment of a vast, dynamic galaxy, where even transient visitors can leave a lasting impact.”
Alongside capturing a stunning image, the primary scientific aim of the observation session was to obtain the comet’s spectrum, which corresponds to the wavelengths of the emitted light.
The resulting spectra provide critical insights into the composition and chemistry of the comet, enabling scientists to understand its changes as it navigates through the solar system.
“The main goal was to observe the color of the comet to glean information about the composition and size of the coma dust particles, as well as to obtain the spectrum for direct chemical analysis,” noted Dr. Mace.
“We were thrilled to witness the growth of the comet’s tail and to see our first hints of chemistry from the spectrum, indicating particle changes since earlier Gemini observations.”
“These observations yield both awe-inspiring visuals and invaluable scientific data,” asserts Dr. Bryce Bolin, a researcher at Eureka Scientific.
“Each interstellar comet acts as a messenger from another stellar system, and by examining its light and color, we can begin to appreciate the diversity of worlds beyond our own.”
Infrared images of 3I/Atlas taken by the James Webb Space Telescope
NASA/James Webb Space Telescope
3I/Atlas, an interstellar visitor, is noted for being one of the most carbon-rich comets observed, suggesting a formation in an environment vastly different from our solar system.
Since July, astronomers have been monitoring 3I/Atlas. While many findings indicate it resembles typical comets, several peculiar features hint at a more exotic origin, including the emission of water gas at distances from the sun typically unobserved in solar system comets.
Martin Codinner from NASA’s Goddard Space Flight Center in Maryland, along with his team, has utilized the James Webb Space Telescope to capture some of the most intricate observations of the comet.
Codinner’s team studied 3I/Atlas in early August, when they were approximately three times the distance from the sun compared to typical comets. At this distance, temperatures rise enough for water to transition from ice to gas, resulting in comets usually generating water vapor and dust, known as a coma.
However, their findings revealed that the coma of 3I/Atlas contains a significantly higher amount of carbon dioxide relative to water, with an 8:1 ratio. This is 16 times more than what is generally seen in other comets from our solar system at this distance from the Sun.
High carbon dioxide levels could imply that comets formed in planetary systems where carbon dioxide ice is more prevalent than water ice, suggests Matthew Genge from Imperial College London. “This may indicate a fundamental difference in planetary system formation compared to ours,” Genge adds.
When planetary systems initially form, there are differing quantities of dust, gas, and water vapor found at varying distances from stars. Over time, stars expel gas, leaving behind solid materials. If the progenitor star of 3I/Atlas expelled water vapor from locations where comets developed earlier than in our solar system, it could account for its unique composition, Genge articulates.
The scarcity of water vapor may also be attributed to previous close encounters with other stars, Genge notes. Codinner offers that water could be concealed deep within the comet’s crust, thus insulated from higher temperatures, which is indeed unusual.
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In a new paper published in the journal Iscience, astrophysicists at the University of Fudan have explored the potential for sending nanocrafts from Earth to black holes located 20-25 light years away. This mission aims to investigate the properties of strong gravitational fields and the fundamental aspects of physics.
Black holes represent the strongest gravitational fields known in the universe and serve as ideal laboratories for testing Einstein’s general theory of relativity under extreme conditions. Professor Bambi discusses the speculative nature and challenges of launching small spacecraft to the nearest black hole, yet emphasizes that it remains a plausible endeavor. Image credit: Cosimo Bambi, doi: 10.1016/j.isci.2025.113142.
“While we lack the necessary technology today, it may be feasible in 20 or 30 years,” stated Professor Cosimo Bambi, an astrophysicist and black hole specialist at the University of Fudan.
“Two significant challenges lie ahead: identifying a nearby black hole and developing a probe that can survive the journey.”
Currently, the closest recognized black hole to Earth is Gaia BH1, which was discovered in September 2022 and is located 1,560 light-years away.
However, it is anticipated that many undiscovered black holes may exist closer to Earth.
Simple estimations suggest that, despite significant uncertainties, the closest black hole could potentially be within only 20-25 light years.
“Our understanding of stellar evolution implies that black holes might be hidden just 20 to 25 light years from Earth, but detecting them is not straightforward,” noted Professor Bambi.
“Since black holes do not emit or reflect light, they are nearly invisible to telescopes.”
“Scientists typically rely on observing nearby stars and their interactions with light to identify and study these elusive objects.”
“New methods have been developed for detecting black holes, and I believe it is reasonable to expect the discovery of something nearby within the next decade.”
Once a target is located, the subsequent challenge will be reaching it.
Traditional spacecraft powered by chemical fuels lack the efficiency needed for such long journeys.
Professor Bambi suggests nanocraft as a promising solution—tiny probes consisting of microchips and light sails.
Lasers from Earth would propel the sails using photons, accelerating the craft to one-third the speed of light.
“At that speed, a craft could arrive at a black hole 20 to 25 light years away within about 70 years,” he explained.
“The data collected would then take roughly another 20 years to return to Earth, leading to a total mission duration of approximately 80-100 years.”
“When the craft nears a black hole, researchers could conduct experiments to answer some of the most pivotal questions in physics.”
“Does a black hole truly possess an event horizon? Can light escape the gravitational pull beyond that point?”
“Do the laws of physics alter in proximity to black holes?”
“Is Einstein’s general theory of relativity upheld in the universe’s most extreme conditions?”
“The laser system alone could cost 1 trillion euros, and currently, we lack the technology to fabricate nanocrafts,” Professor Bambi stated.
“Nevertheless, in 30 years, those costs might decrease, and technological advancements could align with these ambitious concepts.”
“While it may sound quite outlandish and resembles science fiction, past disbeliefs—like the detection of weak gravitational waves or imaging black hole shadows—have been proven wrong over time.”
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Cosimo Bambi. Interstellar missions to test astrophysical black holes. Iscience. Published online on August 7th, 2025. doi:10.1016/j.isci.2025.113142
Hubble Space Telescope Image of Interstellar Comet 3i/Atlas. The telescope tracked the comet, causing background stars to appear as streaks.
NASA, ESA, David Jewitt (UCLA)/Joseph DePasquale (STScI)
The telescope’s observations of the Interstellar Comet 3i/Atlas have shown it resembles a comet found beyond our solar system. Intriguing aspects, like the substantial amounts of water detected even far from the sun, may shed light on the ancient stellar system from which it originated.
Objects from other solar systems that pass through ours are extremely rare. Discovered in July, 3i/Atlas is the third such interstellar visitor, following Oumuamua in 2017 and Borisov in 2019. Remarkably, its visit has only been a few months long.
Scientists speculate that its high speed may indicate that it originates from a star system billions of years older than our own. Initial estimates suggested it has a diameter of approximately 20 kilometers, but details about the extensive plume of water and gas remain limited.
Toni Santana Ross from the University of Barcelona and colleagues have utilized ground-based telescopes to observe the comet and its tail, finding it contains moderate amounts of dust. Notably, the dust appears to increase as the comet approaches the sun, mirroring patterns seen in comets from our outer solar system. “It’s a typical object; there’s nothing particularly strange about it,” states Santana Ross.
Astronomers have also monitored comets via space. Researcher collaborating found that the Hubble Space Telescope might estimate the comet’s size between 320 meters and 5.6 kilometers, and it likely started off much smaller.
Comets usually contain ice, which vaporizes as they near the sun, creating water vapor in their tails. Utilizing the Neil Gehrels Swift Observatory Satellite, Zexi Xing from Auburn University has detected water in the comet’s tail located significantly farther from the sun than is typical for comets. The amount of water detected suggests that about 20% of the comet’s surface is responsible for this production, exceeding typical solar system comet proportions.
Such prolific water generation may indicate that 3i/Atlas originates from a star system much older than ours, hypothesizes Cyrielle Opitom at the University of Edinburgh. This is due to older stellar systems generally having higher water content compared to other molecules. “It might be that because it formed earlier, it retains more water than other molecules, but it’s premature to reach a conclusion,” she remarks.
Astronomers are also scouring historical data to determine if the telescope mistakenly detected a comet. Adina Feinstein and her team at Michigan State University have found that the transit exoplanet survey satellite (TESS) was operationally searching for planets around other stars and incidentally captured a comet between May 7 and June 3. “It just happened that we were observing the exact region where 3i/Atlas was at that moment,” says Feinstein.
The comet was found to be surprisingly bright at that time, suggesting it was releasing significant amounts of water or gas even at considerable distances from the sun. “We didn’t detect transits in regions of our solar system where water would typically start to react,” highlights Feinstein.
In this distant region, the likelihood of finding water is low, with gases such as carbon monoxide and carbon dioxide being more common, according to Opitom. “This is a pattern seen in comets from our solar system; they can exhibit activity at much greater distances due to these volatile materials.”
Yet, the fact that it was active so far from the sun could indicate that this comet has not been significantly exposed to starlight throughout its life, notes Matthew Jenge from Imperial College London.
“What this implies is that this comet was ejected from the fringes of another solar system,” Genge describes. While the exact cause of its ejection is uncertain, it’s possible that gravitational forces from a nearby star could have set it on a trajectory towards us, he explains.
Opitom mentions that the James Webb Space Telescope has recently conducted its observations and that astronomers will analyze the data in the upcoming weeks, promising more insights into 3i/Atlas soon.
As comets approach their closest point to the sun in October, astronomers will have the opportunity to measure the gases they emit. This will provide important insights not only into the characteristics of the comet itself but also into the composition of the molecules in its active tail, which may reveal details about the formation of 3i/Atlas, according to Opitom.
Similar to previous interstellar objects, speculations about potential alien technology exist, but Santana Ross has found no supporting evidence. “If you take a holiday photo and see something tall with a long neck and four legs, you might think of it as an alien, but it’s most likely a giraffe,” he quips. “There’s no reason to believe this is anything unusual or evidence of something extraordinary.”
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Recent analysis of new images from the NASA/ESA Hubble Space Telescope reveals that the nucleus of 3i/Atlas measures between 320 m (1,000 ft) and 5.6 km (3.5 miles).
Hubble captured this image of 3i/Atlas, which was located 446 million km (277 million miles) from Earth on July 21, 2025. Image credits: NASA/ESA/David Jewitt, UCLA/Joseph Depasquale, Stsci.
3i/Atlas was discovered on July 1, 2025, by the Asteroid Land Impact Trastor Alt System (ATLAS) funded by NASA.
Its orbit is the most dynamically extreme among recorded solar system objects.
New observations from Hubble have provided astronomers with a more precise estimation of the comet’s solid icy nucleus size.
“The maximum diameter of the nucleus is 5.6 km, but it averages around 320 m,” stated David Jewitt, an astronomer from UCLA, along with his colleagues.
“Hubble’s images offer tighter constraints on the nucleus’s size compared to earlier ground-based measurements, although the solid core of the comet is not currently visible directly even with Hubble.”
“Data from other NASA missions, like Webb, TESS, Neil Gehrels Swift Observatory, and WM Keck Observatory, will further enhance our understanding of comets, including their chemical composition.”
Hubble also detected indications of dust plumes ejected from the sun-warmed side of the comet, along with dust tails drifting away from the nucleus.
The new findings indicate a dust loss velocity that aligns with the first comet observed at roughly 480 million km (300 million miles) from the Sun.
This behavior closely resembles the characteristics of a previously seen sun-bound comet observed within our solar system.
A notable difference is that this interstellar visitor originates from planetary systems beyond our Milky Way galaxy.
3i/Atlas speeds through the solar system at an astonishing rate of 209,000 km (130,000 miles) per hour, marking the highest speed ever recorded for visitors to our solar system.
This remarkable velocity indicates that comets have been traversing interstellar space for billions of years.
The gravitational pull from countless stars and nebulae has contributed to its increased speed.
The longer 3i/Atlas journeys through space, the faster it moves.
“No one knows the origin of this comet; it’s like catching a glimpse of a bullet for a thousandth of a second,” Dr. Jewitt observed.
“You can’t accurately trace that back to determine where you commenced your path.”
“This latest interstellar traveler represents a previously undetected group of objects, enriching the narrative that has gradually unfolded.”
“This achievement is now possible due to the powerful Sky Survey capability we previously lacked. We’ve reached a new milestone.”
Conceptual image of a spacecraft navigating near a black hole
Liuzishan/Getty Images
An interstellar spacecraft designed to explore a black hole could transmit data back to Earth in roughly 100 years.
Cosimo Bambi from the University of Hudang in Shanghai has devised a framework for such missions utilizing technologies projected to be available within the next 20 to 30 years.
By approaching a black hole, we can validate Albert Einstein’s theory of general relativity and uncover the behavior of fundamental physical constants in extreme gravitational fields.
The nearest well-known black hole is approximately 1500 light years away. However, within our Milky Way galaxy, there is estimated to be one black hole for every 100 ordinary stars. This suggests a significant likelihood of locating a black hole within 20 to 25 light years, says Bambi.
Identifying a black hole poses challenges, as these entities do not emit light; astronomers must infer their existence by observing their gravitational influence on surrounding stars.
Reaching a black hole within 25 light years of our solar system will require advanced technological developments, but according to Bambi, “it’s achievable.” Within a century, spacecraft could be minuscule, featuring sails that cover 10 square meters and propelled by light. Such crafts could theoretically accelerate to about one-third the speed of light through pulses from high-powered lasers.
“Currently, light sails and nanocrafts appear to be the most viable options for interstellar travel since they can achieve speeds approaching that of light,” Bambi states. However, he estimates that the power required for an effective laser system could reach approximately 1 trillion euros today.
To validate predictions concerning general relativity, it may be necessary to dispatch two miniature spacecraft or release a secondary probe as the primary nanocraft nears a black hole. The secondary craft would venture closer to the black hole, while the primary craft remains at a safe distance, gathering data and relaying it back to Earth.
Gerlan Lewis from the University of Sydney acknowledges that while the challenges are significant, the proposal is far from impossible.
However, the extensive time frame for the proposed mission introduces a possibility that nanocrafts could become outdated by the time they reach their destination. Lewis remarks, “Considering 100 years of technological advancement, can we truly predict what kind of propulsion system might exist then?”
“A mission to black holes would likely resemble this proposal, akin to how we might imagine the advancements of the 20th century, 500 years in the past,” he adds.
Lewis points out that Bambi’s plans do not address how to decelerate the nanocrafts upon arrival at the black hole. Bambi suggests that the simplest approach is to not slow the vehicle at all, but rather deploy a probe to transmit data back to the main craft for Earth delivery.
“In such scenarios, the probes won’t stop around the black hole; they will merely pass by. Some may be drawn into the black hole, which should provide sufficient data to analyze the black hole’s gravitational field,” he explains.
Sam Baron at the University of Melbourne describes Bambi’s framework as one of the most “speculative” research papers he has encountered, but notes that a century ago, the construction of the Large Hadron Collider would have seemed like science fiction.
“I believe utilizing small-scale technologies is likely the way forward,” he observes. “The question remains whether we can indeed engineer something that meets all the criteria outlined in this paper.”
Bambi emphasizes that human beings cannot personally venture to black holes due to the extreme accelerative forces—around 10,000 g—that nanocraft would need to endure. “Unless we discover a wormhole in the fabric of space-time to provide a shortcut,” he notes.
“We really need a nearby wormhole like in the movie Interstellar” to facilitate human missions,” he concludes. “Unfortunately, my assessment is that wormholes are purely theoretical at this point.”
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NASA’s Juno spacecraft may be tasked with intercepting interstellar objects
NASA/JPL-Caltech
Interstellar objects passing through our solar system make a brief journey around the sun before heading back into deep space. While astronomers can capture images of comet 3i/Atlas traversing our universe, is there a possibility of intercepting this object?
Researchers globally are investigating several strategies, including repurposing European Space Agency (ESA) missions and rerouting existing NASA endeavors to intervene. However, the task is complicated by the comet’s speed of 60 km/sec and the limited preparation time available.
One notable proposal comes from Avi Loeb at Harvard University, who suggests that the interstellar object “Umuamua is akin to an alien spacecraft; I made a similar assertion regarding 3i/Atlas.” Loeb and his team have published a paper, which, despite not being peer-reviewed, indicates that NASA’s Juno spacecraft could adjust its orbit around Jupiter to rendezvous with 3i/Atlas on March 14th next year.
Nonetheless, this idea faces challenges. Mark Burchell from the University of Kent emphasizes the aging spacecraft’s limitations. Launched in 2011, Juno was initially slated to end its mission with a collision into Jupiter’s surface in 2021, which has been delayed until September this year. It has already experienced two technical issues this year, both resolved by engineers.
“The current orbit allows for closer views of Jupiter and a pass by Io [Jupiter’s moon] in 2023. By 2024, it will be exposed to significant radiation, which is unsurprising given the performance anomalies observed that necessitate a restart,” Burchell explains. “If those modifications are successful and the instruments function properly, there might be valuable data to acquire.”
In a post on X,Jason Wright from Penn State has also voiced skepticism regarding this concept, highlighting that the spacecraft has limited fuel and systematic engine issues.
Another potential avenue to observe 3i/Atlas closely is through the ESA’s Jupiter Ice Moon Explorer (Juice). Luca Conversi from ESA mentions that they are considering this possibility. “We acknowledge this valuable opportunity and are currently assessing the technical feasibility. However, we can’t divulge too much at this stage,” Conversi states.
Despite Juice being closer to 3i/Atlas than Earth, it cannot alter its course towards the comet. “I’m uncertain if redirecting it to a comet is practical. Astrodynamics is far more complex than depicted in science fiction films, and altering a spacecraft’s trajectory is quite challenging,” comments Conversi.
Presently, several spacecraft, including Mars Reconnaissance Orbiter and Mars Odyssey, are in orbit around Mars and nearing the end of their operational lifespans. Research conducted by Michigan State University and colleague Atsuhiro Yaginuma suggests that while this method has advantages, it’s unclear whether these spacecraft possess sufficient fuel for such a journey.
The ESA is developing another mission aimed at improving the chances of approaching interstellar objects in the future. The Comet Interceptor spacecraft, scheduled for launch in 2029, is set to await the discovery of comets or interstellar objects that can be targeted at a stable position between Earth and the Sun, facilitating exploration. These missions are rare, as scientists often do not know what the target will be or its appearance timeline.
Colin Snodgrass at the University of Edinburgh, who serves as the deputy lead of the Comet Interceptor, elaborates that this mission would “require a bit of additional maneuverability” to effectively intercept fast-moving objects like 3i/Atlas. For these swift visitors, he suggests a broader mission with a streamlined payload. “If the goal is simple speed, minimize non-essential equipment and prioritize fuel mass,” he advises.
Another future concept involves deploying small satellites in large orbits monthly. “This would distribute them across Earth’s orbit,” Snodgrass explains. “At any time, one of them could return to Earth and leverage gravity to navigate to interesting locations.”
Astrometric endeavors, such as the legacy investigation of space and time, could quickly enhance our understanding of the frequency of these objects entering our solar system, improving prior warnings about their arrival. “When they are moving rapidly, timely notifications can make a significant difference. Instead of providing alerts months ahead of perihelion, having earlier warnings will significantly impact our response,” Snodgrass remarks.
Astronomers utilizing the Gemini North telescope at NSF’s International Gemini Observatory have observed the interstellar comet 3i/Atlas as it passes through our cosmic neighborhood.
This image from the Gemini North Telescope Multi-Object Spectrometer (GMOS-N) showcases the interstellar comet 3i/Atlas. Image credits: International Gemini Observatory/Noirlab/NSF/Aura/K. Meech, Ifa&U. Hawaii / Jen Miller & Mahdi Zamani, Noirlab.
Interstellar objects are those that emerge from and traverse beyond our solar system.
Ranging from several meters to a few kilometers in size, these cosmic fragments are remnants from the formation of the host star’s planetary system.
As they orbit their stars, interactions with the gravitational pull of nearby planets and stars can eject them into interstellar space, allowing them to traverse other solar systems.
Studying interstellar visitors provides critical insights into distant star systems.
They carry valuable information about chemical elements, including their formation timelines and locations, offering scientists glimpses into the formation of planetary systems throughout the history of the Milky Way galaxy.
3i/Atlas marks the third interstellar object discovered, following 1i/Oumuamua in 2017 and 2i/Borisov in 2019.
Astronomers suspect that numerous interstellar objects might regularly pass through our solar system, but capturing them is challenging as they are only visible when telescopes are oriented correctly at the right time.
Multiple teams worldwide utilize various telescopes to monitor 3i/Atlas during its brief visitation, enabling them to collectively assess its key properties.
While many aspects remain unknown, 3i/Atlas is already recognized as distinct in comparison to 1i/Oumuamua and 2i/Borisov.
Previous observations suggest that 3i/Atlas could have a diameter of up to 20 km (12 miles).
New comets typically exhibit highly eccentric orbits, which define how much the object’s path deviates from a perfect circle.
An eccentricity of 0 indicates a circular orbit, while 0.999 signifies a highly elongated ellipse.
Objects with an eccentricity greater than 1 follow paths that do not loop around the Sun and come from, then return to, interstellar space.
The eccentricity of 3i/Atlas is recorded at 6.2, classifying it as a highly hyperbolic interstellar object.
In contrast, “Oumuamua’s” eccentricity was around 1.2, and Borisov’s was about 3.6.
As of now, 3i/Atlas resides in Jupiter’s orbit, approximately 465 million km (290 million miles) from Earth and 600 million km (370 million miles) from the Sun.
On December 19, 2025, it will come within roughly 270 million km (170 million miles) of Earth, posing no threat to our planet.
The closest approach to the Sun will occur around October 30, 2025, at a distance of 210 million km (130 million miles).
During this close approach, it is expected to travel at about 25,000 km (15,500 miles) per hour.
The latest image of 3i/Atlas was obtained using the Gemini North Telescope Multi-Object Spectrometer (GMOS-N).
“The sensitivity and scheduling precision of the International Gemini Observatory played a critical role in observing this interstellar wanderer,” remarked Martin Still, NSF Program Director at the International Gemini Observatory.
“We eagerly anticipate the wealth of new data and insights as this object warms in sunlight before continuing its cold, dark journey through interstellar space.”
Paths of interstellar comet 3I/Atlas through the solar system
NASA/JPL-Caltech
The interstellar entities currently traversing our solar system may include one of the oldest comets ever observed.
Comet 3I/Atlas was identified earlier this month near Jupiter’s orbit, moving at approximately 60 km per second and estimated to be about 20 km in size. It is the third recognized interstellar object in our solar system, having passed near Mars in October before entering the solar orbit.
Matthew Hopkins from Oxford University and his team utilized data from the ESA Gaia spacecraft, which cataloged billions of stars in our galaxy, to simulate the comet’s speed and trajectory, revealing its point of origin. It seems to have emerged from an area close to our galaxy, which is about 13 billion years old, specifically from what is referred to as a thick disk.
“Objects from the thicker disk tend to be quicker,” explains Hopkins, noting that the previous two identified interstellar objects (Oumuamua in 2017 and Comet Borisov in 2019) exhibited a decline in speed. “Their velocities aligned with expectations for thin disk objects.”
Modeling by the team indicates that 3I/Atlas may have originated from a star nearly 8 billion years old, potentially twice the age of our sun, hinting at it being one of the oldest comets ever witnessed. “This might be the oldest comet I’ve encountered,” Hopkins states. Interstellar objects are typically ejected early during a star’s lifecycle and are often propelled by interactions with massive planets.
Hopkins mentioned that ancient stars are likely to possess lower metallicity compared to our sun, implying that these comets might have a higher water content. If this hypothesis holds, we may witness significant water activity from the comet as it nears the sun in the upcoming months.
This could be our first interaction with another star, providing insights into pristine materials that have existed for billions of years, unaltered since before Earth’s formation. “I believe many interstellar objects we’ve encountered are our first meetings with stars, even those that are 8 billion years old,” Hopkins asserts. “They have likely traversed vast distances through empty space before approaching us.”
The astronomer utilizing ESO’s Extremely Large Telescope (VLT) has unveiled a new image of 3i/Atlas, marking it as the third interstellar object documented.
This VLT/FORS2 image, captured on July 3, 2025, depicts interstellar comet 3i/Atlas. Image credit: ESO/O. Hainaut.
3i/Atlas was identified a week ago by the NASA-supported Atlas Survey Telescope in Riojartad, Chile.
Commonly referred to as C/2025 N1 (ATLAS) and A11PL3Z, this comet is approaching from the direction of Sagittarius.
“In contrast to objects within the solar system, its highly eccentric hyperbolic orbit indicates its interstellar origin,” ESO astronomers stated.
Currently, 3i/Atlas is approximately 4.5 AU (670 million km, or 416 million miles) away from the Sun.
Interstellar objects pose no danger to Earth, maintaining a distance of at least 1.6 AU (240 million km, or 150 million miles).
Around October 30, 2025, it will make its closest approach to the Sun at a distance of 1.4 AU (210 million km, or 130 million miles).
“In the VLT time-lapse, you can observe 3i/Atlas moving to the right over approximately 13 minutes,” the astronomer remarked.
“These observations were gathered using FORS2 equipment at the VLT on the night of July 3, 2025, just two days post-discovery of the comet.”
“At the conclusion of the video, all frames are compiled into a single image.
“However, this record will not endure as the comet approaches Earth and becomes less visible.”
“As it currently traverses more than 600 million km from the Sun, 3i/Atlas is heading towards the inner solar system, expected to reach its closest approach to Earth in October 2025,” they noted.
“During that time, 3i/Atlas will be obscured by the Sun, but observations should resume in December 2025.
“Telescopes globally, including the VLT, will persist in monitoring this extraordinary celestial visitor to gather more insights into its structure, composition, and origin.”
Low-density amorphous ice is one of the most prevalent solid materials in the universe and plays a crucial role in deciphering numerous well-known anomalies of liquid water. Despite its significance and discovery nearly 90 years ago, its structure remains a topic of debate. In a recent study, researchers from the University of London and Cambridge found that prior computer simulations of low-density amorphous ice were influenced by a disturbed structure where the ice was not entirely amorphous. Instead, it contained small crystals measuring 3 nm in width, slightly wider than a single DNA strand. In their experimental studies, actual samples of amorphous ice, which formed through different methods, were recrystallized (i.e., warmed up). They observed that the resulting crystal structure varied based on the method used to generate the amorphous ice. The researchers concluded that if the ice was completely disordered, it would not retain any imprint of its previous shape.
Low-density amorphous ice structure: Many small crystals (white) are hidden in the amorphous material (blue). Image credits: Michael B. Davis, UCL & Cambridge University.
“We now have a solid understanding of what the most common ice structures in the universe look like at the atomic level,” states Dr. Michael Davis, a researcher at the University of London and Cambridge.
“This is significant because ice is involved in numerous cosmological processes, including planet formation, galaxy evolution, and the movement of matter throughout the universe.”
For their investigation, Dr. Davis and his colleagues utilized two computer models of water.
They simulated the freezing of water molecules in these virtual “cages” by cooling to -120 degrees Celsius (-184 degrees Fahrenheit) at various rates.
These different cooling rates affected the proportions of crystalline and amorphous ice produced.
The researchers determined that low-density amorphous ice, as evidenced by X-ray diffraction studies, appears to align with a mixture of up to 20% crystallinity and 80% amorphous structure (i.e., researchers fired X-rays at ice and analyzed the deflection patterns).
Using an alternative method, they created a large “box” filled with numerous small ice crystals tightly packed together.
The simulation then disordered the regions between the ice crystals, resulting in structures remarkably similar to those obtained from the initial approach of 25% crystalline ice.
In additional experimental efforts, scientists generated actual low-density amorphous ice samples through various methods, including deposits of water vapor onto extremely cold surfaces (mimicking how ice forms on interstellar dust) and from high-density amorphous ice (ice crushed at very low temperatures).
These amorphous ice samples were then gently heated to provide energy for the formation of crystals.
They noted variations in the structure of the ice depending on its origin, particularly regarding the arrangement of molecules in a hexagonal (6x) formation.
This provided indirect evidence that low-density amorphous ice contained crystalline constituents.
Should it be entirely disordered, the ice would lack any memory of its prior form.
The findings raised further inquiries about the nature of amorphous ice, such as whether crystal size varies based on the formation method, and whether truly amorphous ice is achievable.
“Water is essential to life, yet our understanding is still incomplete,” remarked Professor Michael Ryde from Cambridge University.
“Amorphous ice may be key to explaining many anomalies observed in water.”
“Ice holds potential as a high-performance material in space,” added Dr. Davis.
“It can shield spacecraft from radiation and supply fuel in the form of hydrogen and oxygen.”
“Understanding the various structures and properties is critical.”
Moreover, this research touches upon a speculative theory regarding the origins of life on Earth.
This theory posits that life’s building blocks were transported here on an icy comet, known as Panspermia.
“Our findings indicate that this ice might be a suboptimal transport medium for these biological molecules,” stated Dr. Davis.
“This is due to the reduced space available for partial embedding of these components in the crystal structure.”
“Nonetheless, the theory could still hold merit, as there are amorphous regions within the ice capable of storing and concealing life’s building blocks.”
“Ice on Earth captivates our curiosity due to our warm climate,” observed University College professor Christophe Salzmann from the University of London.
“You can see the intricate order of snowflakes in their symmetry.”
“Ice elsewhere in the universe has long been viewed as a frozen snapshot of liquid water: a disordered arrangement that is fixed in place. Our findings suggest that this perception is not entirely accurate.”
“Our results also prompt questions regarding the properties of amorphous materials in general.”
“Such materials are vital in advanced technologies.”
“For instance, fiberglass used for data transmission must be amorphous or disordered to function.”
“If these materials contain small crystals, their performance can potentially be enhanced by removing them.”
The findings were documented in a paper published today in the journal Physical Review B.
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Michael Benedict Davis et al. 2025. Low-density amorphous ice contains crystalline ice grains. Phys. Rev. B 112, 024203; doi:10.1103/PhysRevB.112.024203
3i/Atlas is only the third celestial object ever detected, following the interstellar asteroid 1i/Oumuamua in 2017 and the interstellar comet 2i/Borisov in 2019.
Images of 3i/Atlas captured by the Atlas telescope. Image credit: University of Hawaii.
The 3i/Atlas is currently about 670 million km (420 million miles) from the Sun and is expected to make its closest approach in October 2025, moving just within Mars’ orbit.
It is estimated to be up to 20 km (12 miles) in diameter, traveling at around 60 km (37 miles) per second relative to the Sun.
This comet poses no threat to Earth, remaining within a distance of 240 million km (150 million miles), which is more than 1.5 times the distance between the Earth and the Sun.
3i/Atlas is an active comet. As it approaches the Sun, the heat causes frozen gases to turn into vapor, releasing dust and ice particles into space and initiating the formation of a glowing coma and tail.
However, by the time it reaches its closest point to Earth, it will be obscured by the Sun. It is expected to be visible again by early December 2025, providing astronomers with an opportunity for further research.
“Finding possible interstellar objects is extremely rare, and it’s thrilling to see the Atlas telescope catch this asteroid,” said a representative.
“These interstellar visitors allow us to glimpse something intriguing from solar systems beyond our own.”
“3i/Atlas is the largest ever observed, yet numerous such objects traverse our inner solar system each year.”
“The likelihood of an impact with Earth is minimal, occurring less than once in 10 million years, but Atlas is consistently scanning the sky for potentially hazardous objects.”
Astronomers across Hawaii, Chile, and other nations are tracking the comet’s progression.
They seek to learn more about the composition and behavior of this interstellar visitor.
“It is precisely their foreign nature that makes interstellar objects like 3i/Atlas so remarkable,” an ESA astronomer stated.
“While all planets, moons, asteroids, comets, and life forms in our solar system share a common origin, our interstellar visitors are genuine outsiders.”
“They are remnants from other planetary systems, providing clues about the formation of worlds beyond our own.”
“It may take thousands of years before humans visit planets in another solar system, and interstellar comets give us the chance to stimulate our curiosity as we interact with something from another world.”
“These icy nomads offer a rare, tangible link to the broader galaxy. This material is fundamentally different from our own and is formed in unique environments.”
“Visiting such objects connects humanity with the universe on a grander scale.”
Following the interstellar asteroid 1i/Oumuamua and comet 2i/Borisov, 3i/Atlas is the third identified object and the second comet from outside the solar system.
This image was captured on July 2, 2025, with an Itemescope.net T72 telescope in Riojartad, Chile, depicting the interstellar comet 3i/Atlas. Image credit: Filipp Romanov/CC by-sa 4.0.
3i/Atlas was discovered by a NASA-funded research telescope dedicated to the Atlas (Asteroid Surface Impact Last Altar System) project on July 1, 2025, in Riojartad, Chile.
The interstellar comet approached from the direction of constellations and is currently about 670 million km (420 million miles) away.
“Since the initial report, pre-discovery observations have been gathered from archives of three different Atlas telescopes globally and from Zwicky’s transitional facility at Palomar Observatory in San Diego County, California,” a NASA astronomer wrote in a statement.
“These pre-discovery observations date back to June 14th, 2025.”
Known as 3I/ATLAS, C/2025 N1 (ATLAS), and A11PL3Z, it currently measures approximately 4.5 AU (670 million km, or 416 million miles) away.
Comets pose no threat to Earth, maintaining a safe distance of at least 1.6 AU (240 million km, or 150 million miles).
It is predicted to reach its closest approach to the Sun around October 30th, 2025, at a distance of 1.4 AU (210 million km, or 130 million miles).
Its size and physical characteristics are being studied by astronomers worldwide.
This diagram illustrates the trajectory of 3i/Atlas as it traverses the solar system. Image credit: NASA/JPL-Caltech.
If the brightness of 3i/Atlas is attributed to reflecting sunlight at a typical albedo of 10%, its diameter would be approximately 100-200 times greater than the estimated length of 20 km for Oumuamua and about 50-100 times larger than the estimated size of Borisov.
“If all three objects are indeed rocky, the mass of 3i/Atlas is more than 10 million times greater than that of Oumuamua and at least 100,000 times the core mass of Borisov.”
“This is remarkable because we expect high-mass objects to be exceedingly rare.”
“Based on data from the major asteroid belts of the solar system, we would expect millions of objects like Oumuamua for each object with the mass of 3i/Atlas.”
3i/Atlas should remain visible to ground telescopes until September 2025.
It is anticipated to reappear on the opposite side of the Sun by early December, enabling further observations.
“Based on its trajectory, 3i/Atlas seems to enter in a retrograde orbit, inclined at 175 degrees relative to Earth’s orbital plane from the thin disc of stars in the Milky Way,” explains Professor Roeb.
“In the upcoming months, we will gain further insights into the properties of 3i/Atlas based on data from various ground-based telescopes and the NASA/ESA/CSA James Webb Space Telescope, including the NSF/DOE Vera C. Rubin Observatory in Chile.”
Astronomers are laying out welcome mats for newly discovered visitors making their way through our solar system.
This particular object is categorized as a comet and marks only the third confirmed interstellar visitor in recorded history to traverse our cosmic neighborhood.
The comet, named 3i/Atlas, poses no threat to Earth, maintaining a distance of about 150 million miles while it accelerates. As reported by NASA.
This interstellar comet was initially discovered on Tuesday by The final alert system for the asteroid’s terrestrial impact (Atlas) located in Rio Hartado, Chile. The research telescope, funded by NASA, is actually two telescopes from Hawaii and one in Chile, in addition to a fourth in South Africa, all dedicated to scanning the sky multiple times nightly for asteroids that could threaten Earth.
Researchers examined archived data from three different Atlas telescopes and Zwick temporary facilities at the Palomar Observatory in California, uncovering observations that would corroborate the findings. Other telescopes worldwide have also joined the initiative, as stated by NASA.
Interstellar Comet 3i/Atlas. David Rankin/Saguaro Observatory
The comet is located around 420 million miles away and is rapidly traveling from the direction of the constellation Sagittarius. NASA commented in a blog post regarding the findings. Sagittarius is a prominent constellation in the Southern Hemisphere and indicates the center of the Milky Way galaxy.
The agency noted that 3i/Atlas will make its closest approach to the sun around October 30th, passing roughly 130 million miles away, close to Mars’ orbit.
NASA indicated that the comet will remain observable from ground-based observatories until September, providing scientists with the opportunity to gather additional details about these cosmic visitors, including their size. After September, 3i/Atlas will be too close to the sun for telescopes to observe, but it is expected to become visible again in early December, as it reemerges on the far side of the sun.
The upcoming months will present a rare chance to study these celestial tourists traveling through the solar system. The first confirmed interstellar object, observed in 2017 by the University of Hawaii’s Pan-Starrs1 telescope, was the rocky body named “Oumuamua” (Hawaiian for first visitor), notable for its reddish hue and elongated cigar-like shape. As noted by NASA.
The only other known interstellar visitor is 2i/Borisov, a comet discovered in 2019 by amateur astronomer Gennady Borisov.
Comet 3i/Atlas is the third interstellar object detected in the solar system
E. Guido, M. Rocchetto, J. Ferguson
Interstellar objects have been observed speeding through the solar system, prompting both amateur and professional astronomers globally to direct their telescopes toward them, refining their orbital models to confirm their status as visitors from other stars.
The comet was initially designated A11PL3Z and marks the third documented interstellar object. The first, ‘Oumuamua, was identified in October 2017, shortly after its closest approach to Earth. Its bizarre acceleration sparked numerous theories, including the possibility that it might be an alien spacecraft. The second interstellar object, Comet Borisov, was discovered in 2019, allowing for more extensive observations early in its journey through the solar system.
The A11PL3Z was first detected by NASA’s Asteroid Terrestrial Impact Last Alert System (ATLAS). Earlier images of the object, once overlooked, were identified in data collected on June 14. New observations are underway in Chile and beyond through the Deep Random Survey. The Minor Planet Center—charged with the observation and reporting of such entities—has now officially named it 3I/ATLAS, acknowledging both its classification as the third interstellar object and the discoverers.
The object measures approximately 20 km wide and is estimated to move at around 60 km per second, gradually accelerating due to the sun’s gravitational pull. By October, it will reach its closest point to the Sun, passing within two astronomical units (twice the distance from Earth to the Sun) before swinging away and exiting our solar system.
The anticipated trajectory of 3i/Atlas marks its position as only the third interstellar object to be recorded in the solar system
CSS, D. Rankin
This creates a limited window for studying 3i/Atlas, although its visibility offers more time for observation compared to other interstellar entities. “They move through the solar system at astonishing speeds,” states Mark Norris from the University of Central Lancashire, UK. “It’s a race against time to learn as much as we can about them.”
Unfortunately, the technology needed to launch missions to intercept and investigate these celestial visitors remains out of reach, according to Norris. “Even if we started today, it would be too late,” he concludes. However, this may evolve soon, as the European Space Agency (ESA) aims to deploy a comet interceptor mission into space in 2029, where it will await encounters with newly discovered comets and interstellar bodies.
For now, astronomers must depend on existing telescopes to observe 3i/Atlas from a distance. “As we can track it until the end of the year, we have sufficient time to refine its trajectory, and there’s still time to focus the spectrometer on it,” mentions Richard Moisle. Our team is already eager to pinpoint the earliest possible observations. Everyone is highly enthusiastic and ready for what’s ahead.”
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Illustration of NASA’s New Horizons spacecraft navigating the outer solar system.
Joe Olmsted/STScI
After departing from our solar system, NASA’s New Horizons spacecraft finds itself considerably distant from Earth, causing the stars of the Milky Way to appear in notably different positions compared to our terrestrial views. Astronomers are harnessing this altered perspective to determine the location of galaxy probes, marking the first instance of intergalactic navigation.
Launched in 2006, New Horizons initially observed Pluto before continuing beyond, traversing the Kuiper Belt—an immensely expansive region of rocky debris and dust billions of miles from the Sun. Currently, the spacecraft is hurtling through space at tens of thousands of kilometers per hour.
When gazing at the night sky from Earth, stars seem widely spread apart, so unless equipped with a strong telescope, their positions appear constant from various locations. In contrast, the New Horizons perspective reveals a significant shift in star positions due to the parallax effect. This phenomenon was demonstrated in 2020 when the probe captured images of two nearby stars, Proxima Centauri and Wolf 359.
Now, Todd Lauer from the U.S. National Institute of Light Change Astronomy in Arizona and his team have utilized this effect to gain a new perspective. They accomplished this by comparing images of Proxima Centauri and Wolf 359 taken by the probe with measurements from the Gaia Space Telescope.
“There’s a three-dimensional map of the galaxies around us, allowing you to see your position,” says Lauer. “Using your own camera on a spacecraft offers incredible accuracy.”
To determine the spacecraft’s location, Lauer and his team analyzed the star positions detected by the New Horizons camera, tracing their lines back to the closest intersection point. They then referenced the precise locations of both stars from the Gaia star map to ascertain this point’s relation to the solar system.
This two-frame animation illustrates the changing position of Proxima Centauri as observed from Earth and New Horizons.
Nearly every spacecraft utilizes NASA’s Deep Space Network (DSN) to determine its position within a margin of tens of meters through a network of radio transmitters on Earth. In contrast, the parallax method provides a less precise estimation, determining New Horizons’ location within a 6,000-kilometer sphere, roughly half the distance from Earth to the Sun.
“We don’t aim to replace the Deep Space Network; this is merely a proof-of-concept demonstration,” Lauer notes. Yet, advancements in cameras and equipment could enhance accuracy by up to 100 times.
Employing this technique for interstellar navigation could yield superior location accuracy compared to the DSN. This not only facilitates the spacecraft’s journey further from Earth but also provides more reliable location tracking, enabling autonomous operations without relying on radio signals from the solar system. Massimiliano Vasile from Strathclyde University in the UK emphasizes this potential.
“When we venture to real stars, we’re talking about light-years,” Vasile explains. “The signal from the Deep Space Network must traverse all the way there, moving at light speed, taking years to reach its destination.”
However, Vasile points out that no agency currently has a mission aimed at deeper exploration of interstellar space, limiting the immediate utility of this technique.
The predicted trajectory of A11PL3Z marks it as the third interstellar object observed in the solar system
CSS, D. Rankin
Potential interstellar bodies are now observed zipping through our solar system, and both amateur and professional astronomers globally are racing to direct telescopes towards these phenomena, refine their trajectory models, and ultimately validate their status as visitors from another star.
The object provisionally named A11PL3Z represents the third interstellar entity detected to date. The asteroid ‘Oumuamua was first seen in October 2017, just three days after it passed closest to Earth, and its unusual acceleration sparked a variety of hypotheses, including the possibility of it being an alien spacecraft. The second identified object, Comet Borisov, was observed in 2019, allowing for closer examination given its early passage through the solar system.
A11PL3Z was first identified by the Deep Random Survey in Chile, a group of amateur astronomers. However, a review of earlier observations by other teams revealed that it was initially spotted on June 14 by NASA’s Asteroid Terrestrial-impact Last Alert System (ATLAS). It is estimated to measure approximately 20 km in width and is currently traveling at around 66 km/s, accelerating as it gets pulled in by solar gravity. In October, it will reach its closest point to the Sun, passing within two astronomical units (the Earth is twice the distance from the Sun) before swinging away and exiting the solar system.
This provides a limited window for studying A11PL3Z, though it’s more than that available for previous interstellar objects, which were seen hurtling towards the solar system. “These objects move through the solar system at incredible speeds,” remarks Mark Norris from the University of Central Lancashire. “They are quite transient, which restricts our ability to learn about them.”
Sadly, the prospect of sending missions to intercept and study A11PL3Z is beyond the reach of current technology, notes Norris. “If we were to launch a mission today, it would be too late,” he states. However, the European Space Agency (ESA) is planning a comet interceptor mission set for launch in 2029, which would remain in space to await the arrival of newly discovered comets and possibly interstellar objects.
For the time being, astronomers are relying on existing telescopes to observe A11PL3Z from a distance. “We anticipate we will be observing it by the end of the year, giving us ample time to prepare our spectrometers once we finalize the trajectory,” shares Richard Moisle. When will our observers discern its visibility? There’s a palpable excitement as everyone is prepared and looking forward to this opportunity.
At the time of this writing, over 100 observations of A11PL3Z have already been logged, and the Minor Planet Center—the official body responsible for monitoring and reporting such celestial entities—is expected to confirm its interstellar classification later today.
A cold, dense cloud in the Milky Way’s interstellar medium is about four to five orders of magnitude denser than its diffuse counterparts, and a team of astronomers from Boston University, Harvard University, and Johns Hopkins University has found evidence that two to three million years ago, our solar system encountered one of these dense clouds, which may have been so dense that it disrupted the solar wind.
Offers othersThe interstellar material through which the Sun has traveled over the past few million years indicates the presence of cold, dense clouds that could have had dramatic effects on the heliosphere. Image credit: NASA/JPL-Caltech.
Most stars generate winds that move through the surrounding interstellar medium.
This motion creates a cocoon that protects the planet from interstellar material. The Sun’s cocoon is the heliosphere.
It’s made up of a constant stream of charged particles called the solar wind, which extends far beyond Pluto, enveloping the planet in what astronomers call a “local bubble.”
It protects us from radiation and galactic rays that can alter DNA, and scientists think it’s part of the reason why life on Earth evolved.
A cold interstellar cloud compressed the heliosphere, temporarily placing Earth and other planets in the solar system outside of its influence, according to a new study.
“Our paper is the first to quantitatively show that there was an encounter between the Sun and something outside our solar system that affected Earth’s climate,” said Professor Merab Auffar of Boston University.
“Stars move, and this paper shows that not only do they move, but they undergo dramatic changes.”
To study this phenomenon, Professor Orpher and his colleagues essentially went back in time and used advanced computer models to visualize where the Sun was located two million years ago, along with the heliosphere and the rest of the solar system.
They also mapped the path of a “localized cold cloud ribbon” system, a series of large, dense and very cold clouds made mainly of hydrogen atoms.
Their simulations showed that one of the clouds near the edge of the ribbon, a “local cold cloud,” may have collided with the heliosphere.
If this had happened, Earth would have been fully exposed to interstellar matter, where gases and dust would have mixed with atomic elements left over from the exploded star, such as iron and plutonium.
Normally, the heliosphere filters out most of these radioactive particles, but without protection they could easily reach Earth.
This is consistent with geological evidence showing increased levels of the isotopes iron-60 and plutonium-244 in the oceans, the moon, Antarctic snow and ice cores from the same period, according to the paper.
This timing also coincides with temperature records indicating a cold period.
“It is rare for our cosmic neighbors outside our solar system to have an impact on life on Earth,” said Harvard University professor Avi Loeb.
“It’s exciting to discover that our passage through dense clouds millions of years ago may have exposed the Earth to much greater amounts of cosmic rays and atomic hydrogen.”
“Our findings open a new window into the evolution of life on Earth and its relationship with our cosmic neighbours.”
“External pressure from localized lynxes of cold clouds could have continuously blocked the heliosphere for hundreds to millions of years, depending on the size of the cloud.”
“But as soon as Earth left the cold cloud, the heliosphere engulfed all the planets, including Earth.”
“It’s impossible to know exactly what effect the cold clouds had on the Earth, such as whether they caused ice ages.”
“But there are other cool clouds in the interstellar medium that the Sun likely encountered in its first few billion years.”
“And we’ll probably encounter many more over the next million years or so.”
The authors are currently working to determine where the Sun was 7 million years ago, and beyond.
Pinpointing the position of the Sun and cold cloud systems millions of years ago is made possible by data collected by ESA’s Gaia mission, which has produced the largest 3D map of the galaxy ever, showing in unprecedented detail how fast stars move.
“This cloud is certainly from our past, and if we passed through something this massive, we would have been exposed to interstellar material,” Prof Auffar said.
“This is just the beginning. We hope this paper opens the door to further exploration of how the solar system was influenced by outside forces in the ancient past, and how these forces may have shaped life on Earth.”
of paper Published in today’s journal Natural Astronomy.
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M. Offer othersIt is possible that Earth was directly exposed to cold, dense interstellar material 2 to 3 million years ago. Nat AstronPublished online June 10, 2024; doi: 10.1038/s41550-024-02279-8
Illustration of a protection bubble around the sun (yellow dot) and the earth (blue dot)
Harvard Radcliffe Institute
Two to three million years ago, the solar system encountered galactic-scale turbulence and collided with dense interstellar clouds, potentially altering both the Earth's climate and evolution.
Only recently have researchers been able to map the Sun's orbit through the Galaxy, particularly in relation to the relatively dense hydrogen clouds that pass through the interstellar medium, the vast expanse of space between star systems.
the current, Merab Offer A research team from Boston University in Massachusetts has found evidence that one of these clouds, a “local cold cloud ribbon” in Lynx, likely intersects with the Sun's heliosphere.
The heliosphere is a protective cocoon or bubble formed by the solar wind pushing out to the edge of the solar system. Within the heliosphere, the planet is protected from the worst gamma radiation in the galaxy.
The new study proposes that as the solar system passed through the interstellar cloud, the heliosphere retreated from it and moved inward toward the Sun. The researchers think that the heliosphere may have shrunk so much that Earth was outside the protective cocoon provided by the solar wind, perhaps for around 10,000 years.
Merab and his colleagues used the European Space Agency's Gaia satellite to map the location of the dense, cold clouds and the sun's past orbit.
Ofer says the heliosphere's encounter with the cold cloud coincides with deposits of the elements plutonium-244 and radioactive iron-60 in Antarctic ice, deep-sea cores and lunar samples. These elements, which originated from distant supernovae, would have been captured in interstellar clouds and deposited while Earth was outside the heliosphere.
“There are signs of an increase in these elements over the past two years. [million] “The solar cloud record going back 3 million years provides compelling evidence that the Sun did in fact pass through it around 2 million years ago,” Offer says. “The exposure of Earth to a cloud of cold interstellar material and the associated increase in atmospheric hydrogen and radiation almost certainly had a major impact on Earth and its climate.”
Sarah Spitzer The University of Michigan researcher says the paper provides “compelling” evidence that the heliosphere was exposed to a much denser interstellar cloud two to three million years ago. As the solar system passed through that dense, cold cloud, Earth would have been outside the heliosphere and directly exposed to the interstellar environment, she says.
“Understanding this can teach us about the impact interstellar material has had on life on Earth in the past,” Spitzer says, “but it also helps us better understand the impact the heliosphere has on life on Earth today, what would happen if Earth were exposed to interstellar material again in the future, and when that might happen.”
Evan Economo Researchers from Japan's Okinawa Institute of Science and Technology say it's intriguing to consider how encounters in “our nearby space” could have influenced the environment experienced by life on Earth.
“The heliosphere is part of the extended environment experienced by life on the Earth's surface, influencing climate and radiation from space,” he says. “If we had been outside the heliosphere for a period of time, it could have altered the evolutionary trajectory of a wide range of life, including humans. Such connections are highly speculative at this point, but they provide us with new research directions.”
Humanity has always dreamed of traveling beyond our solar system to the stars, but the vastness of the universe has kept us grounded. Our closest star, Proxima Centauri, is a staggering 4.24 light years away, which is too far for us to wait patiently.
Recently, on April 23, NASA launched the Advanced Composite Solar Sail System from New Zealand, a system that uses lightweight sails to propel spacecraft instead of traditional rockets. This development has excited both experts and science fiction fans, as it opens up possibilities for long-distance space travel.
How solar sail works
Instead of using thrusters and fuel like traditional spacecraft, solar sail systems use reflective sails to absorb momentum from photons emitted by the sun. This technology enables spacecraft to gain acceleration without the limitations of fuel. In space, where there is no air resistance, a slight push from the sun is all that’s needed for propulsion.
Solar sails operate similar to sailing ships, utilizing the momentum of photons for movement. By harnessing the sun’s energy, spacecraft can travel far distances at manageable speeds.
How fast can an interstellar probe travel with a solar sail?
The speed of a solar sail system depends on factors like the size of the sail, spacecraft mass, and distance from the sun. With creative maneuvers like slingshot maneuvers and potential laser boosts, spacecraft using solar sails can achieve speeds close to 20% of the speed of light.
Future solar sail systems could reach speeds up to 20 percent of the speed of light. – Image credit: NASA/Aero Animation/Ben Schweighart
Will humanity ever be able to sail to another planet?
Potentially, solar sail technology could pave the way for human interstellar travel in the future. However, there are challenges, such as sustaining long-term missions for generations and addressing relativistic effects caused by near-light speed travel.
What exactly is NASA's solar sail mission?
NASA’s Advanced Composite Solar Sail System is a demonstration of solar sail technology that aims to test a new lightweight boom made of flexible materials. The mission involves a CubeSat deploying an 80 square meter sail in orbit to gather data for future solar sail missions.
About our experts
patrick johnson is an associate professor at Georgetown University with expertise in quantum mechanics. He authored the book “Star Wars Physics” and has contributed to scientific journals like Physical Review.
NASA stays in touch with its space probes, like Voyager 2, through the Deep Space Network (DSN), which consists of radio receiving antennas located in three different spots globally. These locations include Goldstone in California, Robredo near Madrid, and Tidbinbilla near Canberra.
Voyager 2 can only be observed from the southern hemisphere, making the DSS-43 antenna at the Australian site the sole antenna on Earth that can communicate with the spacecraft.
Currently positioned more than 20 billion kilometers from Earth, Voyager 2 has a transmitter that outputs approximately 23 watts (around eight times more powerful than a typical cell phone). By the time a radio signal reaches Earth, it has only about one-tenth of this power.
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To detect this extremely faint signal, DSS-43 and Voyager 2’s transmitters use narrowband, high-frequency signals that are highly directional and transmitted at slow bit rates.
Advanced signal processing techniques, minimal interference, and the fact that radio signals can travel through space with little obstruction allow DSS-43 to overcome long distances.
The antenna can transmit a signal to Voyager 2 at a much higher power level (up to about 400,000 watts) than it receives. This strong output can be easily picked up by the spacecraft even at far distances.
This piece (by Elouise Pace) addresses the question, “How can we communicate with Voyager 2, which is billions of miles away?”
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Explore our topFascinating factsMany more fascinating scientific pages.
astronomer using Mid-infrared measuring instrument The NASA/ESA/CSA James Webb Space Telescope's (MIRI) detected molecules ranging from relatively simple ones like methane to complex compounds like ethanol (alcohol) and acetic acid. interstellar ice One low-mass protostar and one high-mass protostar: toward NGC 1333 IRAS 2A and IRAS 23385+6053, respectively.
This image taken by Webb's MIRI instrument shows the region near the IRAS 23385+6053 protostar. Image credit: NASA/ESA/CSA/WRM Rocha, LEI.
Complex organic molecules (COM) are molecules with six or more atoms, including at least one carbon atom.
These materials are the raw material for future exoplanetary systems and are therefore of essential importance in understanding the chemical complexity developed in star-forming regions.
If this material becomes available in a primitive planetary system, it could facilitate the planet's habitability.
In a new study, astronomers Will Rocha, Harold Linnaerts and colleagues at Leiden University used Webb's mid-infrared instrument to determine the extent of COM ice in two protostars, NGC 1333 IRAS 2A and IRAS 23385+6053. We investigated the characteristics.
They were able to identify a variety of COMs, including ethanol (alcohol) and perhaps acetic acid (a component of vinegar).
“Our discovery contributes to one of the long-standing questions in astrochemistry,” Dr. Rocha said.
“What is the origin of COM in the Universe?” Are they created in the gas phase or in ice? Detection of COM in ice is based on the solid phase at the surface of cold dust particles It suggests that chemical reactions can build complex types of molecules. ”
“Some COMs, including those detected in the solid phase in our study, were previously detected in the warm gas phase, so they are now thought to originate from ice sublimation.”
“Sublimation is the change from a solid directly to a gas without becoming a liquid.”
“Therefore, we have hope that detecting COM in ice will improve our understanding of the origins of other, larger molecules in the universe.”
This figure shows the spectrum of the NGC 1333 IRAS 2A protostar. Image credit: NASA/ESA/CSA/Leah Hustak, STScI.
The researchers also detected simpler molecules such as formic acid, methane, formaldehyde, and sulfur dioxide.
“Sulfur-containing compounds, such as sulfur dioxide, played an important role in promoting metabolic reactions on early Earth,” the researchers said.
“Of particular interest is that one of the investigated origins, NGC 1333 IRAS 2A, is characterized as a low-mass protostar.”
“NGC 1333 IRAS 2A may resemble the early stages of our solar system.”
“Therefore, the chemicals identified around this protostar may have been present during the earliest stages of the development of the solar system and were later delivered to the proto-Earth.”
“All of these molecules could become part of comets, asteroids, and ultimately new planetary systems as icy material is transported inside planet-forming disks as protostar systems evolve.” '' said Dr. Ewain van Dyschoek, an astronomer at Leiden University.
“We look forward to using more web data in the coming years to follow this astrochemical trajectory step by step.”
of the team paper It was published in the magazine astronomy and astrophysics.
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WRM Rocha other. 2024. JWST Young Protostar Observation (JOYS+): Detection of icy complex organic molecules and ions. I.CH.FourSo2,HCOO−,OCN−,H2Colorado, Cooh, Switzerland3CH2Oh, CH3Cho, channel3Ocho and CH3Coo. A&A 683, A124; doi: 10.1051/0004-6361/202348427
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