Tag Archives: Neptune

New Study Questions the Classification of Uranus and Neptune as Ice Giants

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A recent study conducted by researchers at the University of Zurich indicates that the compositions of Uranus and Neptune might be less icy than previously assumed.

Uranus could be classified as an ice giant (left) or a rock giant (right), depending on the assumptions of the model. Image credit: Keck Institute for Space Studies / Chuck Carter.

“Uranus and Neptune remain poorly understood, making the designation of ice giants too simplistic,” states Dr. Luca Morf, a student at the University of Zurich.

“Models based on physical data incorporate too many assumptions, while empirical models fall short in complexity.”

“Our approach combines both methodologies to create an interior model that is unbiased, yet physically coherent.”

The research commenced with a stochastic density distribution inside the planets.

Subsequently, the team calculated the gravitational fields of the planets in alignment with observational data to infer their likely compositions.

The process was iterated to achieve the closest alignment between the model and the empirical data.

Employing a new, unbiased yet fully physical framework, scientists have revealed that the internal compositions of the solar system’s ice giants are not restricted to ice alone.

“We initially proposed this concept nearly 15 years ago, and now we possess a numerical framework to substantiate it,” remarked Professor Ravit Held of the University of Zurich.

“This expanded spectrum of internal compositions suggests both planets could be rich in water or minerals.”

The study also sheds light on the enigmatic magnetic fields of Uranus and Neptune.

In contrast to Earth’s defined north and south magnetic poles, the magnetic fields of Uranus and Neptune exhibit greater complexity, featuring multiple poles.

“Our model introduces a so-called ‘ionized water’ layer that generates magnetic dynamos that account for the observed non-dipolar magnetic fields,” noted Professor Held.

“Moreover, we discovered that Uranus’ magnetic field has a more profound origin compared to that of Neptune.”

While the findings are promising, some ambiguities linger.

“A significant challenge is that physicists still have limited understanding of how materials behave under the extreme pressure and temperature conditions in planetary cores, which could influence our conclusions,” Morf added.

Notwithstanding the uncertainties, these new findings open avenues for possible internal composition scenarios, challenging longstanding assumptions and informing future materials science research under planetary conditions.

“Depending on model assumptions, both Uranus and Neptune have the potential to be classified as rock giants or ice giants,” Professor Held remarked.

“At present, the data is insufficient to differentiate between the two, highlighting the necessity for dedicated missions to Uranus and Neptune to uncover their true natures.”

A paper detailing this research was published in this week’s journal Astronomy and Astrophysics.

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Luca Morf and Ravit Held, 2025. Ice or rock? Convection or stability? New interior models for Uranus and Neptune. A&A 704, A183; doi: 10.1051/0004-6361/202556911

Source: www.sci.news

Webb captures Aurorae on Neptune for the first time while detecting trihydrogen

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Emission from trihydrogen cations of large atmospheres flames (h3+) It has been used for over 30 years to study the global interactions of Jupiter, Saturn and Uranus with the surrounding space environment, revealing the process of aurora formation. However, despite repeated attempts, and against models that predict it should exist, this ion has proven elusive in Neptune. Currently, using observations from the NASA/ESA/CSA James Webspace telescope, astronomers have detected Neptune’s trihydrogen cations and distinct infrared South Aurorae.

This composite image, created using data from the NASA/ESA Hubble Space Telescope and the NASA/ESA/CSA James Webbspace Telescope, shows the aurora activity (cyan bevel) in Neptune. Image credits: NASA/ESA/CSA/STSCI/HEIDI HAMMEL, Aura/Henrik Mellin, University of Northumbria/Leafletcher, University of Leicester/Stefanie Millam, NASA-GSFC.

“In the past, astronomers have seen appetizing hints for Aurora’s activities in Neptune,” said Henrik Mellin, an astronomer at Northumbria University and his colleagues.

“However, imaging and confirmation of Aurorae in Neptune has been avoiding astronomers for a long time despite successful detections on Jupiter, Saturn and Uranus.”

“Neptune was a missing part of the puzzle when it came to detecting the giant planet of the solar system, Aurorae.”

In this study, the authors analyzed the obtained data. Webb’s Near-Infrared Spectroscopy (NIRSPEC) June 2023.

In addition to the image of the planet, astronomers have characterized the composition and acquired spectra to measure the temperature of the planet’s upper atmosphere (ionosphere).

They discovered a very prominent efflux system indicating the presence of trihydrogen cations.

“In Neptune’s Webb image, the glowing aurora appears as a spot, represented by cyan,” the astronomer said.

“The aurora activity seen in Neptune is markedly different from what we are used to seeing here on Earth, or even Jupiter and Saturn.”

“Instead of being trapped in the north and south poles of the planet, Neptune’s aurora is located in the mid-latitudes of the planet. Think about where South America is on Earth.”

“This is due to the strange nature of Neptune’s magnetic field, originally discovered by NASA’s Voyager 2 in 1989, tilting 47 degrees from the planet’s axis of rotation.”

“The activity of the aurora is based on where the magnetic field converges into the planet’s atmosphere, so Neptune’s aurora is far from the rotating pole.”

“The groundbreaking detection of Neptune’s Aurorae helps us understand how Neptune’s magnetic fields interact with particles flowing through far-flung areas of the solar system.

Researchers were also able to measure the temperature above the Neptune atmosphere for the first time since the flyby of the Voyager 2.

Their results suggest why Neptune’s Aurorae remained hidden from astronomers for a long time. The upper atmosphere of the Neptune was cooled several hundred degrees.

For many years, astronomers have predicted the strength of Neptune Aurorae based on temperatures recorded by Voyager 2.

“A rather cold temperature would result in a very prominent aurorae,” the scientist said.

“This cold temperature could be the reason why Neptune’s Aurorae remains undetected for a long time.”

“Dramatic cooling suggests that even though Earth is more than 30 times more seated from the Sun compared to Earth, this area of ​​the atmosphere can change dramatically.”

result Today I’ll be appearing in the journal Natural Astronomy.

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H. Merin et al. Discovery of h3+ JWST and Neptune’s infrared aurorae. Nut AthlonPublished online on March 26th, 2025. doi:10.1038/s41550-025-02507-9

Source: www.sci.news

Discovering Aurora on Neptune for the First Time with NASA’s Webb Telescope

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The Northern and Southern Lights Vermillion, Amethyst, and Jade Ribbons are some of the most distinctive features of the Earth. However, our planet has no monopoly of the Aurora. Scientists spy on them throughout the solar system, weaving the Martian sky into Saturn, Jupiter and even some of Jupiter’s fiery softening.

The light shines in the sky Uranus too. However, the aurora around Neptune, the farthest planet of our Sun, has long escaped astronomers.

That was changed by the powerful infrared equipment installed in the James Webb Space Telescope. In a study published in the journal on Wednesday Natural Astronomy scientists reveal unique auroras spilling on either side of Neptune’s equator. This contrasts with the sparkling Gossamers, arcing at Poles in other worlds.

Astronomers are excited that the Aurora Hunting Quest has been completed over decades. “Everyone is very excited to prove it’s there, as we thought,” he said. Rosie Johnson an astrophysics researcher at Aberystwyth University in Wales who was not involved in new research.

The discovery allows scientists to study previously out-of-reach aspects of Neptune. “They use the aurora to understand the shape of the magnetic field on planets looking at the invisible,” he said. Karl Schmidt Boston University planetary astronomers were not involved in new research.

Each world produces aurora differently, but it is basically the same. Energy particles (often from the sun, but sometimes from the eruption of a lunar volcano) hit the atmosphere and bounce back the gas. The collision of the particles causes a temporary flash of light. And if there is a magnetic field in the world, it will guide the position…

Luckily, the Webb Telescope, released in 2021, came to rescue.

Heidi Hammel Another astronomer of the University Association for Astronomical Studies and the author of the research, has been studying Neptune since the 1980s. She said that if Webb “is powerful enough to see the early galaxies of the universe, it would be strong enough to see something like Neptune’s Aurorae.” “And by Golly, that was the case.”

Using the telescope’s near-infrared spectrometer, astronomers captured Neptune’s infrared aurora in June 2023. This is because Neptune has an unstable magnetic field tilted to 47 degrees from the planet’s spin axis.

New Webb observations also reveal why Neptune’s Auroras has never been visible until now. Almost 40 years ago, Voyager 2 recorded a temperature of about 900 degrees Fahrenheit in the Neptune’s upper atmosphere. However, the Webb telescope shows that the temperature has dropped nearly 200 degrees. This low temperature means that the aurora is a dimmer.

In fact, Neptune’s Aurora said, “It’s less than 1% of the expected brightness and explains why I’ve never seen it before.” James O’Donohew a planetary astronomer at the UK’s Reading University and one of the authors of the study. “But that means we have a new mystery in our hands now. How did Neptune get so cold?”

Neptune’s Strange Light Show detection may bring your answers closer.

“The Aurora is like a TV screen,” he said. Lee Fletcher a planetary scientist at the University of Leicester in the UK and one of the authors of the study. They said, “We are able to see the delicate dance of the magnetosphere processes.

Source: www.nytimes.com

Our first encounter with Aurora on Neptune

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Green spots show where the aurora brightens the sky in Neptune

NASA, ESA, CSA, STSCI, Heidi Hammel (Aura), Henrik Melin (Northumbria University), Leigh Fletcher (University of Leicester), Stefanie Milam (NASA-GSFC)

For the first time, researchers discovered infrared aurora swirling in Neptune’s atmosphere, examining decades of scientific speculation.

When NASA’s Voyager 2 mission was flew by Neptune in 1989, I found an appetizing hint of aurora activity in the clouds of Ice Giant. However, scientists were unable to verify the phenomenon at the time because existing equipment was too weak. Now, James Webb Space Telescope (JWST) has finally provided the power to detect them.

“This really was a fulfillment of long-standing expectations.” Heidi Hammel Washington, DC, Astronomical Research Association.

Hammel and her colleagues used NirSpec from JWST, a powerful infrared imaging tool, to capture spectral images of Neptune and analyze light at various wavelengths emitted by the planet. In 2023, researchers used musical instruments to detect Uranus’ infrared aurora. This time I found it on Neptune too.

The images allowed Hammel and her team to begin building a map of Neptune’s magnetic field. This is particularly exciting as the planet is known to have some of the rarest magnetic poles in the solar system.

Unlike Earth, Jupiter, and Saturn, Neptune’s magnetic poles are not at the center of their rotating poles. Instead, “they are offset by almost half the planet’s radius,” says Hammel. As a result, the aurora appears as an irregular mass far closer to the equator.

In addition to detection of Auroras, observations of JWST showed that the ionosphere of Neptune, a layer of charged particles that covers several planets, was cooled. Now, on average, it’s about 10% colder than when the Voyager 2 passed 34 years ago. A similar change was detected on Uranus.

The authors of the new study are unclear why this cooling occurred, but they hope that the upcoming JWST observation period, scheduled for 2026, will provide more clues.

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Source: www.newscientist.com

Astronomers find scorching-hot Neptune close to TOI-3261

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Orbit of newly discovered exoplanet TOI-3261 (also known as TIC 358070912) is an inactive main sequence star located 300 parsecs (978.5 light years) away in the constellation Hydra.

Artist's concept of the super-hot Neptunian exoplanet TOI-3261b. Image credit: NASA/JPL-Caltech/K. Miller, Caltech & IPAC.

The radius of this newly discovered exoplanet, named TOI-3261b (TIC 358070912b), is 3.82 Earth's radius.

Its mass is 30.3 times that of Earth, more than twice the median mass of Neptune-sized planets in longer orbits.

To determine these properties, astronomer Emma Nabby from the University of Southern Queensland and her colleagues used data from NASA's Exoplanet Survey Satellite (TESS), the Las Cumbres Observatory's Global Telescope, and the ESPRESSO and HARPS instruments. I used

“In our measurements, TOI-3261b is exactly hot neptune desert “The planets are so rare that their rarity evokes images of desolate landscapes,” the astronomers said in a statement.

“This type of exoplanet is similar in size and composition to our own Neptune, but it orbits very close to its star.”

The planet orbits its parent star, TOI-3261, every 21 hours.

Such a narrow orbit has so far allowed the planet to belong to the same group as only three other ultrashort-period, high-temperature Neptunes: LTT-9779b, TOI-849b, and TOI-332b.

“TOI-3261b has proven to be an ideal candidate for testing new computer models of planet formation,” the researchers said.

“One reason hot Neptunes are so rare is that it's difficult to maintain a thick gaseous atmosphere in the immediate vicinity of the star.”

“Because stars are massive, they exert a large gravitational force on surrounding objects and can strip away layers of gas surrounding nearby planets.”

“It also releases a lot of energy and blows away the gas layer.”

“Both of these factors mean that a hot Neptune like TOI-3261b may have started out as a much larger Jupiter-sized planet and then lost most of its mass.”

The TOI-3261 system is about 6.5 billion years old, and the planet began as a much larger gas giant, the researchers said.

“But it likely lost mass in two ways: by photoevaporation, where energy from the star causes gas particles to dissipate, and by gravity from the star, which strips layers of gas from the planet. tidal separation,” the scientists said.

“It's also possible that the planet formed further away from the star, where both of these effects would be less strong and it would be able to maintain an atmosphere.”

“The planet's remaining atmosphere is one of its most interesting features and will likely invite further atmospheric analysis, perhaps helping to elucidate the formation history of this hot Neptunian desert dweller.”

“TOI-3261b's density is about twice that of Neptune, indicating that the lighter parts of the atmosphere have been removed over time, leaving only the heavier components,” the researchers added.

“This suggests that the planet must have started out with a variety of elements in its atmosphere, but at this stage it's difficult to know exactly what they are.”

This finding is reported in the following article: paper Published in astronomy magazine.

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Emma Naby others. 2024. Survival in the Hot Neptunian Desert: Discovery of the ultrahot Neptune TOI-3261b. A.J. 168, 132; doi: 10.3847/1538-3881/ad60be

Source: www.sci.news

Astronomers find a rare hot Neptune that defies convention

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The number of planets in our solar system used to be limited to only eight, excluding Pluto. These include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune, often remembered by the phrase “My cultured mother served us nachos.” However, with the discovery of exoplanets since 1992, the list has expanded dramatically. These exoplanets, such as PSR B1257+12 b and 51 Pegasus b, have added to the existing planets, making it challenging for students to remember them all.

Scientists have observed a pattern among exoplanets concerning their masses, distances from their stars, compositions, and other factors. Interestingly, there are very few planets with masses similar to Earth and Jupiter orbiting very close to their stars, with less than 5% of Earth’s distance from the Sun.

Research indicates that the scarcity of what they call “Hot Neptunes” might be due to the evolution of large planets. As gas giants grow, they either become comparable in size to Jupiter or lose their outer gas layers, leaving behind a rocky core like Earth’s size. Furthermore, astronomers have recently discovered new exoplanets, TOI-2374 b and TOI-3071 b, in what they refer to as Neptune’s desert.

These exoplanets stand out due to their proximity to their stars, with TOI-2374 b having a mass 56 times that of Earth and TOI-3071 b being 68 times the Earth’s mass. Despite their extreme surface temperatures, the exoplanets have not evaporated, possibly due to their high metal contents.

The observations of these exoplanets provide valuable insights for future research and exploration, potentially shedding light on unexplored phenomena in Neptune’s desert.


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Source: sciworthy.com

Astronomers say that a near, warm Neptune has a sulfurous atmosphere

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The warm Neptunian exoplanet, called GJ 3470b (Gliese 3470b), is 96 light years away and orbits a 2 billion year old red dwarf star in the direction of the constellation Cancer.

Artist's impression of the warm-Neptunian exoplanet GJ 3470b. Image courtesy of the University of Wisconsin-Madison Department of Astronomy.

First discovered in 2012, GJ 3470b is the lightest and coolest (over 325 degrees Celsius, or 600 degrees Fahrenheit) exoplanet containing sulfur dioxide.

The compounds are likely a sign of active chemistry taking place in the planet's atmosphere, as radiation from a nearby star explosively breaks down hydrogen sulfide components, which then seek out new molecular partners.

“We never expected to see sulfur dioxide on such a small planet, so finding this new molecule in an unexpected place is exciting because it gives us new ways to understand how these planets formed,” said Professor Thomas Beatty of the University of Wisconsin-Madison.

“And small planets are particularly interesting because their composition depends heavily on how the planet-formation process happened.”

Prof Beatty and his colleagues hope that by observing what exoplanets contain, they can shed light on the principles of planet formation and do just that.

“The discovery of sulphur dioxide on a small planet like GJ 3470b adds another important item to the list of ingredients for planet formation,” Prof Beatty said.

In the case of the GJ 3470b, there are also other interesting features that could help round out that recipe.

The planet orbits the star and passes nearly over the star's pole, meaning that it orbits at a 90 degree angle to the expected orbit of a planet in this system.

The moon is also incredibly close to its star, close enough that light from the star would blow a lot of GJ 3470b's atmosphere out into space.

The team says the planet may have lost around 40% of its mass since it formed.

The misaligned orbit suggests that GJ 3470b was once somewhere else in the system, and at some point, the planet became caught in the gravity of another planet, pulling it into a new orbit and eventually settling in a different neighborhood.

“The migration history that led to this polar orbit and how it has lost so much mass are things we don't typically know about other exoplanet targets that we study,” Prof Beattie said.

“These are important steps in the recipe that created this particular planet, and they help us understand how planets like this one are made.”

“Further analysis of the components remaining in the planet's atmosphere may help us understand why planets like GJ 3470b became so appetizing.”

This month, the authors 244th Meeting of the American Astronomical Society In Madison, Wisconsin.

Source: www.sci.news

New Moons Found Around Uranus and Neptune by Astronomers

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The three newly discovered moons (S/2023 U1, S/2002 N5, and S/2021 N1) are the faintest ever discovered around Uranus and Neptune using ground-based telescopes.

Discovery image of Uranus’ moon S/2023 U1 using the Magellan Telescope on November 4, 2023. Image credit: Scott Sheppard.

The new Uranian moon, tentatively named S/2023 U1, was first discovered by astronomers at the Carnegie Institution for Science on November 4, 2023. Scott Sheppard using the Magellan Telescope at the Las Campanas Observatory.

At just 8 km (5 miles), it is probably the smallest of Uranus’ moons. It takes 680 days to circumnavigate the ice giant.

S/2023 U1 will eventually be named after a character from a Shakespeare play, following Uranus’ outer moon naming conventions.

This discovery brings the total number of moons on this giant icy planet to 28.

Dr. Sheppard also used the Magellan telescope to discover S/2002 N5, the brighter of two newly discovered Neptune moons.

The moon’s diameter is about 23 km (14.3 miles), and it takes almost nine years to circumnavigate the ice giant.

The dimmer moons of Neptune were discovered by Dr. Sheppard and his colleagues using the Subaru telescope.

The star, named S/2021 N1, is about 14 km (8.7 miles) in diameter and has an orbital period of almost 27 years.

S/2002 N5 and S/2021 N1 were both first seen in September 2021.

Both have enduring names based on the 50 Nereid sea goddesses from Greek mythology.

“The orbit around Neptune of S/2002 N5 is determined using observations from 2021, 2022, and 2023, indicating that it was discovered near Neptune in 2003, but is still orbiting the planet. “We were able to trace it back to an object that was lost before it was confirmed,” Sheppard said.

S/2023 U1, S/2002 N5, and S/2021 N1 have far-flung, eccentric, and inclined orbits that occurred when Uranus and Neptune were formed from rings of dust and debris surrounding them, or it suggests that they were captured by the gravity of these planets shortly after our sun is in its infancy.

All giant planets in our solar system, regardless of their size or formation process, have a similar composition of outer moons.

“Even Uranus, which is tilted sideways, has a moon population similar to other giant planets orbiting the sun,” Dr. Sheppard said.

“And Neptune, which likely captured the distant Kuiper Belt object Triton, an event that could disrupt its lunar system, has an outer moon that looks similar to its neighbors. “

This new moon also indicates the existence of a dynamic orbital group of outer moons around Uranus and Neptune, similar to those seen around Jupiter and Saturn.

At Uranus, S/2023 U1 has an orbit similar to Caliban and Stefano.

At Neptune, S/2021 N1 has an orbit similar to Psamate and Neso, and S/2002 N5 has an orbit similar to Thao and Laomedeia.

These groupings suggest that the once larger parent moon was shattered, perhaps by a past collision with a comet or asteroid, leaving shattered debris in an orbit similar to the original larger moon. There is.

Many small lunar fragments are likely present in these groups, but they are generally too small to be efficiently observed with current technology.

These groupings of moons indicate that the early solar system was a very chaotic place, with constant movement and collisions between different objects.

Source: www.sci.news

A recently discovered tiny moon orbits Neptune and Uranus

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Uranus (left) and Neptune (right) have several more moons

NASA, ESA, Mark Showalter (SETI Institute), Amy Simon (NASA-GSFC), Andrew I. Hsu, Michael H. Wong (University of California, Berkeley)

Astronomers have discovered new moons around Uranus and Neptune for the first time in 10 years. These are the faintest moons ever discovered orbiting a planet, confirming a long-held idea about moons in the outer solar system.

Scott Shepherd from the Carnegie Institution for Science in Washington, D.C., discovered these moons using the Magellan Telescope in Chile and confirmed them using several other large telescopes around the world. “We looked about four times deeper than anyone has ever looked,” Shepherd said. “These satellites are at the edge of our capabilities. They’re just faint, faint points of light.”

Typically, when looking for the moon, you can only get a maximum exposure of about 5 minutes before it becomes overexposed and the moon’s movement renders it useless. Shepard and his team got around this problem by taking many of these five-minute images in quick succession, observing them for hours, and then combining the darker parts of the images. This allowed them to find dim points of light shining from the faintest moons ever discovered, as well as the smallest moons ever discovered around each planet.

The new moon around Uranus is tentatively named S/2023 U1, but will eventually be given the name of a Shakespearean character, along with the planet’s other moons. It is only about 8 kilometers in diameter and orbits once every 680 Earth days.

One of the new moons around Neptune is called S/2021 N1, and we await its official name from Greek mythology. With a diameter of about 14 kilometers, it takes about 27 Earth years to orbit the planet, making it the farthest moon from its host planet ever discovered. This is also the darkest moon ever discovered.

Discovery image of Uranus’ new moon S/2023 U1 with scattered light from Uranus and trails from background stars

Scott S. Shepherd/Carnegie Institution for Science

The brighter, larger moon discovered orbiting Neptune is called S/2002 N5. As its name suggests, this satellite was first discovered more than 20 years before, but was lost before astronomers could confirm its orbit. “The moon can get lost really easily,” Shepard says. “Basically, you need really good weather, your telescopes need to work perfectly, and everything needs to go well to detect these satellites.” If something goes wrong and a planned observation is lost, the satellite moves out of orbit and becomes very difficult to find again.

Each of the three new moons has an orbit similar to the other two moons in its planetary system, and these fellow travelers form small groups that orbit together. This means that each of these groups likely formed together when larger moons broke up during the early solar system chaos.

“Until now, it was unclear whether Uranus and Neptune had a group of exomoons like Jupiter and Saturn,” Shepard said. “We believe these are debris from satellites that were once much larger, but we’ll probably find many more smaller satellites.” Unfortunately, we’re reaching the limits of what we can discover with current technology, he says it may take even longer before these smaller moons are discovered around Uranus and Neptune.

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Source: www.newscientist.com

Newly color-corrected image shows that Uranus and Neptune have a greenish-blue hue

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The so-called ice giants Uranus and Neptune are the most distant giant planets in the solar system. Our knowledge of these worlds was revolutionized by his flybys of NASA’s Voyager 2 spacecraft on January 24, 1986 and August 25, 1989, respectively. Since these Voyager encounters, our knowledge of the visible appearance of these worlds has come primarily from images reconstructed from observations from Voyager 2 Imaging Science System (ISS), images were recorded with several separate filters ranging from ultraviolet to orange. In these images, Uranus appears pale green and Neptune appears dark blue, and the perception of the relative colors of these planets has become generally accepted. However, new research has revealed that the two ice giants are actually much closer in color.

Voyager 2/ISS images of Uranus and Neptune, released shortly after the Voyager 2 flybys in 1986 and 1989, respectively, were used in this study to determine the best estimates of the true colors of these planets. The filtered image was compared with the reprocessed version.Image credit: Irwin other., doi: 10.1093/mnras/stad3761.

Professor Patrick Irwin of the University of Oxford said: “While the well-known Voyager 2 image of Uranus was released in close to ‘true’ color, the image of Neptune has actually been stretched and enhanced. As a result, it was artificially too blue.”

“Although artificially saturated colors were known to planetary scientists at the time and images were published with descriptive captions, over time that distinction has been lost. I lost it.”

“By applying our model to the original data, we were able to reconstruct the most accurate representation to date of the colors of both Neptune and Uranus.”

In the study, Professor Irwin and his colleagues space telescope imaging spectrometer On board the NASA/ESA Hubble Space Telescope (STIS) Multi-unit spectroscopic explorer (MUSE) ESO’s Very Large Telescope.

This means that the STIS and MUSE observations can be processed unambiguously to determine the actual apparent colors of Uranus and Neptune.

Astronomers used these data to rebalance the composite color images recorded by Voyager 2’s camera. Hubble’s Wide Field Camera 3 (WFC3).

This revealed that Uranus and Neptune are actually quite similar shades of greenish-blue.

The main difference is that Neptune has a slight hint of additional blue. Models revealed that this is due to Neptune’s thin haze layer.

The study also provides an answer to the long-standing mystery of why Uranus’ color changes slightly during the sun’s 84-year revolution.

The authors first reached their conclusion after comparing images of the ice giant with measurements of its brightness recorded in blue and green wavelengths from 1950 to 2016 by the Lowell Observatory in Arizona.

These measurements showed that Uranus appears slightly greener during the summer and winter solstices, when one of the planet’s poles points toward our star.

However, at the vernal equinox, when the sun is above the equator, the sun takes on a somewhat blue hue.

Part of the reason for this is known to be because Uranus has a very unusual rotation.

During its orbit, it effectively rotates almost sideways. This means that during the planet’s summer solstice, either the north or south pole points almost directly in the direction of the sun and Earth.

This is therefore important because changes in reflectivity in the polar regions have a large effect on Uranus’ overall brightness as seen from Earth.

Astronomers have not been very clear about how or why this reflectance differs.

This led the researchers to develop a model that compares the spectra of Uranus’ polar and equatorial regions.

They found that in polar regions, green and red wavelengths are more reflective than blue wavelengths. Part of the reason is that red-absorbing methane is about half as abundant near the poles as it is at the equator.

But this wasn’t enough to fully explain the color change, so the researchers looked at the gradually thickening icy surface of the planet’s sunlit pole during the summer. We added a new variable to the model in the form of a haze “hood”. We move from the vernal equinox to the summer solstice.

Astronomers believe it is likely made up of particles of methane ice.

When simulated in the model, the ice particles further increased reflection in green and red wavelengths at the poles, providing an explanation for why Uranus is green at the summer solstice.

“This is the first study to match quantitative models with image data to explain why Uranus’s color changes during its orbit,” Professor Irwin said.

“Thus, we prove that Uranus at the summer solstice is greener, not only because methane abundance is reduced in the polar regions, but also because the thickness of brightly scattering methane ice particles is increased. it was done.”

“The misperceptions of Neptune’s colors and the unusual color changes of Uranus have puzzled us for decades. This comprehensive study finally puts an end to both problems. ” said Dr. Heidi Hummel, a researcher at the Association of Universities for Astronomical Research (AURA).

of result will appear in Royal Astronomical Society Monthly Notices.

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Patrick G.J. Irwin other. 2024. Model the seasonal cycle of Uranus’ color and size and compare it to Neptune. MNRAS 527 (4): 11521-11538; doi: 10.1093/mnras/stad3761

Source: www.sci.news

The True Color of Neptune: It’s Not as Blue as Previously Believed

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Voyager 2's original photo of Neptune (left) and the new study's reprocessed image (right)

Patrick Irwin

Neptune's true color is a pale greenish-blue similar to that of Uranus, contrary to popular belief that it is a much deeper blue.

NASA's Voyager 2 spacecraft passed by the outer planet in the 1980s and sent back photos showing the strikingly different colors of Uranus and Neptune.

This is puzzling given their similar size, mass, and chemical composition. Models of the planet's atmosphere can explain some of the fluctuations, such as Uranus' thicker “haze layer” that reflects more white light and makes the planet appear brighter, but these may explain why the planet is It doesn't fully explain why you should have something like that. different shades.

now, Patrick Irwin Researchers at the University of Oxford have processed images from Voyager 2 to show what the planet looks like to the human eye.

The original photo of Neptune taken by Voyager 2 had an enhanced contrast ratio to highlight hard-to-see atmospheric features. In addition to how they balanced the colors to create the final composite image, this also made the planet appear bluer.

Scientists at the time knew this and included these changes in photo captions, but over time the captions became detached from the images and Neptune's deep blue hue became a fact in the public consciousness. According to Irwin, the shrine is now enshrined inside.

Images of Uranus (left) and Neptune (right) created in previous and new research

Patrick Irwin

He and his team developed a model that uses shots taken by the Hubble Space Telescope to convert raw image data into true-color images. This image contains more complete information about the light. This produced similar hues on both planets. “The way the eye works makes true-color images much more boring and bland,” Irwin says.

The researchers also used Hubble images and images from the Lowell Observatory in Arizona to build a model to predict how Uranus' color would change during its long 84-year orbit around the sun. Due to the rotation of the planet, more of the equator is visible at the vernal equinox, and more of the poles are visible at the summer solstice. At the equator, there is more methane and red light is absorbed. The planet also has a hood of reflective, brightening ice particles that forms at its sun-facing poles during the equinoxes, increasing the reflectance of red and green wavelengths.

This helps explain the long-standing mystery of why Uranus appears slightly green on the summer solstice. “We knew there was a hood, we knew there was less methane in the polar regions, but no one had put it all together to be able to explain what was really going on seasonally. “It was,” Irwin said.

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Source: www.newscientist.com