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.”
Source: www.sci.news
