Tag: exploration

The shoreline of Pluto’s frozen nitrogen sea

11:10 am

The shoreline of Pluto's frozen nitrogen sea
Click for full resolution. For original
images go here and here.

Cool image time! In my continuing exploration of the New Horizons’ image archive, I keep finding things that I do not remember ever seeing before. The two New Horizon pictures used to create the panorama to the right (here and here) were taken by the spacecraft only thirteen minutes before its closest approach to Pluto at 7,800 miles on July 14, 2015. It shows the Al-Idrisi mountains — thought to be made up of frozen ice as hard as granite — and the frozen nitrogen sea that pushes against those mountains and squeezes them into their jumbled shape. For scale, the image is estimated to be fifty miles wide.

In December 2015 the science team released a small section of one of two images, focused specifically at that nitrogen sea shoreline, noting:

Great blocks of Pluto’s water-ice crust appear jammed together in the informally named al-Idrisi mountains. Some mountain sides appear coated in dark material, while other sides are bright.

The team however did not release this wider panorama produced by both images, which I think gives a better perspective of what we are looking at.

I posted an even wider shot of this shoreline on January 29, 2026. If you look closely at that picture, you can spot the features to the right, but much smaller seen from a greater distance.

For the larger context, below is a wide shot of Pluto indicating the part of the planet where this image is located.
» Read more

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The weird landscape of Mars’ death valley

11:19 am

Taffy terrain
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on October 28, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this “bands near mesa,” an apt description. What we are looking at is a geological feature unique to Mars, but also unique to only one particular place on Mars, the planet’s death valley, the place in Hellas Basin with the lowest relative elevation of any spot on Mars.

The feature is called taffy terrain. According to a 2014 paper, the scientists posit that this material must be some sort of “a viscous fluid,” naturally flowing downward into “localized depressions.” Those localized depressions however happen to also be at the very basement of Mars.

Note how in some spots the bands appear to have been stripped off, exposing small hollows in which dust has become trapped over time to form ripple dunes.
» Read more

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Webb tracks Uranus’ atmosphere over 15 hours

9:27 am

Uranus and its atmosphere
Click for original image.

Using the Webb Space Telescope, astronomers on January 19, 2025 were able to observe Uranus for fifteen straight hours, tracking the atmosphere’s temperature and structure more completely than ever before.

You can read the peer-reviewed paper here. The false color image to the right, reduced to post here, is just one slice of that dataset. We are looking down at Uranus’ pole, as the rotational tilt is so severe the planet rotates on its side as it orbits the Sun. The grey circles on the outside are the planet’s faint rings. The orange blobs I think are aurora that rotate around the pole at high latitudes, as shown in this video. The orange represents the upper atmosphere.

Led by Paola Tiranti of Northumbria University in the United Kingdom, the study mapped out the temperature and density of ions in the atmosphere extending up to 5,000 kilometres above Uranus’s cloud tops, a region called the ionosphere where the atmosphere becomes ionised and interacts strongly with the planet’s magnetic field. The measurements show that temperatures peak between 3,000 and 4,000 kilometres, while ion densities reach their maximum around 1,000 kilometres, revealing clear longitudinal variations linked to the complex geometry of the magnetic field.

…Webb’s data confirm that Uranus’s upper atmosphere is still cooling, extending a trend that began in the early 1990s. The team measured an average temperature of around 426 kelvins (about 150 degrees Celsius), lower than values recorded by ground-based telescopes or previous spacecraft.

Two bright auroral bands were detected near Uranus’s magnetic poles, together with a distinct depletion in emission and ion density in part of the region between two bands (a feature likely linked to transitions in magnetic field lines). Similar darkened regions have been seen at Jupiter, where the geometry of the magnetic field there controls how charged particles travel through the upper atmosphere.

There is great uncertainty in these conclusions, mostly because the observations are for such a short time. It is like trying to understand the Earth’s climate after looking at it for only one day.

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Saturn’s moon Enceladus, as seen during Cassini’s last close fly-by

1:22 pm

Enceladus as seen during Cassini's last close fly-by
Click for original.

Cool image time! On December 19, 2015 the Saturn orbiter Cassini made its last close fly-by of the moon Enceladus, known best for the many geysers detected on its surface venting water and other carbon-based materials.

The picture to the right, reduced and enhanced to post here, shows that the entire face of this
Saturn’s moon Enceladus, as seen during that fly-by. The moon itself is only about 310 miles across.

Its icy surface is evident, as are the many fractures, some meandering almost like rivers. Interestingly, for some reason there are a lot more craters in the lower hemisphere, while the upper hemisphere is more completely covered with fractures.

The black outline indicates the approximate area captured by the two close-up images below.
» Read more

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Webb imaged a star before it went supernova

11:14 am

Webb detection of a supernova progenitor
Click for original image.

One of the biggest challenges facing astronomers for more than four centuries has been the detection of a star prior to its going supernova. Until very recently, no such detection had ever happened, and so astronomers could only guess at the kind of stars or binary systems that might result in these gigantic stellar explosions.

In recent years the improvement in telescopes, both in orbit and on the ground, has produced some successes, whereby the progenitor star was imaged in archival imagery and found after the explosion. The sample however has been small, and the data limited to only a few wavelengths.

Now, the Webb Space Telescope has made its first detection of a supernova progenitor, in the infrared. That image is to the right, showing the star prior to the June 2025 supernova explosion.

By carefully aligning Hubble and Webb images taken of NGC 1637, the team was able to identify the progenitor star in images taken by Webb’s MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera) in 2024. They found that the star appeared surprisingly red – an indication that it was surrounded by dust that blocked shorter, bluer wavelengths of light. “It’s the reddest, most dusty red supergiant that we’ve seen explode as a supernova,” said graduate student and co-author Aswin Suresh of Northwestern University.

This excess of dust could help explain a long-standing problem in astronomy that could be described as the case of the missing red supergiants. Astronomers expect the most massive stars that explode as supernovas to also be the brightest and most luminous. So, they should be easy to identify in pre-supernova images. However, that hasn’t been the case.

One potential explanation is that the most massive aging stars are also the dustiest. If they’re surrounded by large quantities of dust, their light could be dimmed to the point of undetectability. The Webb observations of supernova 2025pht support that hypothesis.

You can read the peer-reviewed paper here [pdf].

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First visual detection of another star’s heliosphere

9:38 am

A baby star's heliosphere
Click for full image.

Using both the Hubble Space Telescope and the Chandra X-ray Observatory, astronomers have made the first visual detection of another star’s heliosphere, in both X-rays and in the infrared.

The image to the right, cropped to post here.

Astronomers have nicknamed the HD 61005 star system the “Moth” because it is surrounded by large amounts of dust patterned similarly to the shape of a moth’s wings when viewed through infrared telescopes. The wings are formed from material left behind after the formation of the star, similar to the Kuiper Belt in our own solar system. Observations of these wings with NASA’s Hubble Space Telescope showed that the interstellar matter surrounding HD 61005 is about a thousand times denser than that around the Sun.

The wings are the points to the left and right. The star’s young heliosphere, which they dub an “astrosphere,” is the purple glow above and below. From the caption:

In this composite image of HD 61005 in the inset, X-rays from Chandra (purple and white) have been combined with infrared data from Hubble (blue and white). Chandra reveals a bright source of X-rays in the center of the image, which is the star itself surrounded by the star’s astrosphere. The wing-like structure sweeping away from the star in the infrared image is dusty material that remained behind after the formation of the star. These wings have been swept backwards as they fly through space.

As this star and its solar system are very young, what we have is a very dusty accretion disk interacting with a very temperamental baby star.

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Pluto’s splotched surface

12:30 pm

Pluto's splotched surface
For original images go here and here.

Cool image time! The panorama above was created using two photographs (found here and here) taken by New Horizons during its close fly-by of Pluto on July 14, 2015. It looks at Pluto’s western limb, well lit by the Sun, from a distance of approximately 60,000 miles.

I pulled these images from the New Horizons’ archive specifically because I don’t remember ever seeing them publicly released by the science team. More important, they show a surface far more alien than other more well-known New Horizon pictures. Are those round splotches impact craters or some alien type of volcanic caldera? Note also the vertical cracks that appear to divide this terrain near the center.

It would be a serious mistake to make any conclusions. In the emptiness of the outer solar system, the impact rates are going to be far less than in the inner solar system, so assuming impacts is dangerous. Pluto meanwhile has an alien surface of frozen nitrogen seas often filled with floating mountains of frozen water ice. For it to also produce weird volcanic eruptions of nitrogen, sublimating away like bubbling tomato sauce when it is simmering, is quite possible.

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The dimmest galaxy yet found

9:57 am

The dimmest galaxy yet found
Click for original image.

The uncertainty of science: Using ground-based and orbiting telescopes, astronomers think they have identified what might be the dimmest galaxy yet discovered, revealed almost entirely not from its stars but from the four globular clusters that reside within or near it.

The image to the right, cropped and sharpened to post here, shows that galaxy, dubbed CDG-2, along with those four globular clusters. From the press release:

To confirm one of the dark galaxy candidates, astronomers employed a trio of observatories: the NASA/ESA Hubble Space Telescope, ESA’s Euclid space observatory, and the ground-based NAOJ Subaru Telescope in Hawaii. Hubble’s high-resolution imaging revealed a close collection of four globular clusters in the Perseus galaxy cluster, 300 million light-years away. Follow-up studies using Hubble, Euclid, and Subaru data then revealed a faint, diffuse glow surrounding the star clusters – strong evidence of an underlying galaxy.

“This is the first galaxy detected solely through its globular cluster population,” said David. “Under conservative assumptions, the four clusters represent the entire globular cluster population of CDG-2.”

Preliminary analysis suggests CDG-2 has the luminosity of roughly 1 million Sun-like stars, with the globular clusters accounting for 16% of its visible content.

The scientists next claim that 99% of the galaxy’s mass is made up of dark matter, a material no one has yet detected except for the gravitational influence its invisible mass imposes on visible objects. It appears the astronomers don’t believe the mass that has been detected is sufficient to hold this galaxy together, and thus they need dark matter to explain its existence.

I simply wonder if the distances involved simply make the matter hard to see.

No matter. This is a cool discovery, because it tells us there is much out there hidden in the darkness we will always find difficult if not impossible to detect.

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UAE extends mission of its Al-Amal Mars orbiter

8:57 am

Deimos with Mars in the background
Al-Amal’s 2023 image of Deimos, the first good
picture of the moon ever taken. Click for full movie.

The United Arab Emirates (UAE) yesterday announced it is extending the mission of its Al-Amal Mars orbiter (“Hope” in English) to 2028, significantly beyond its initial planned mission of two years.

Launched in July 2020, the Hope Probe successfully entered Mars orbit in February 2021 after a seven-month interplanetary journey, marking a historic achievement as the first Arab nation to reach the Red Planet. Originally designed as a two-year mission to observe and study Mars’ atmosphere, the probe has far exceeded expectations. Since reaching Mars, it has gathered around 10 terabytes of scientific data, shared through more than a dozen datasets with research institutions worldwide.

The probe itself was mostly built by American engineers and organizations, as part of a deal to train UAE students. Once in operation around Mars, the UAE and those students took over almost all operations. It orbits Mars in a very wide orbit, allowing it to study global weather and atmosphere conditions, such as dust storms.

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Pluto’s floating mountains of frozen ice

10:18 am

Pluto's floating mountains
Click for original image.

Cool image time! The picture to the right, rotated, cropped, and sharpened to post here, was taken by New Horizons on July 14, 2015 when it made its close fly-by of Pluto.

The picture looks at the part of Pluto that was close to sunset. Hence the mountain’s long dramatic shadow. The raw image webpage provides little information, including a scale of 0.0 meters, which means nothing. My guess is that these mountains could be several hundred to several thousand feet high based on data from other New Horizon mountain images, but that is a pure guess.

What we think we know is that these mountains are likely made of ice, which at Pluto’s eternally cold environment is as hard as granite. We also think we know that they float on a layer of frozen nitrogen, but because that nitrogen can sublimate into gas when Pluto’s climate warms as its orbit brings it closer to the Sun, the foundation of these mountains is quite unstable. They can roll and drift about, even if they are the size of the Appalachian mountains in the eastern U.S.

I continue to delve into the New Horizons’ archive, and have discovered a trove of quite amazing pictures that hadn’t been featured by the science team during the fly-by. Pluto really is an alien place. Stay tuned, there is more to come!

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A sinuous Martian ridge of uncertain origin

10:06 am

A sinuous ridge of uncertain origin
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 21, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It was posted today by the camera team as a captioned image, with the caption as follows:

The sinuous ridge is approximately 10 meters wide and several kilometers long. The floor surrounding this ridge has been eroding laterally, forming pits and circular features suggestive of removal (sublimation) of subsurface ice. However, landforms such as channels or moraines that might suggest the presence of water or ice are lacking, so the ridge itself does not appear to have formed by fluvial or glacial processes.

Perhaps this curious feature is an exhumed dike formed from magma emanating from Alba Mons in subsurface fractures.

Alba Mons is a gigantic shield volcano to the west.
» Read more

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A sculptured Martian landscape

12:24 pm

Weird Martian landscape
Click for original.

Cool image time! The picture to the right, cropped and sharpened to post here, was taken on December 4, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this landscape “olivine-rich plains”, which is a magnesium iron silicate mineral of some industrial value that is quite common on Earth. Its presence here suggests there could be other valuable minerals in this region.

I post the image because the landscape is so weird and beautiful. The orange color suggests these ridges are covered with dust, if not made of dust entirely. The small areas with a greenish tint that appear to mostly appear on north-facing cliffs could be frost, except this is in the southern hemisphere where north-facing cliffs get more sunlight. As it was autumn when this picture was taken frost is an unlikely explanation.

More likely the green indicates exposures of bedrock or coarser boulders.
» Read more

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Hubble eyes the Egg Nebula

10:48 am

Hubble eyes the Egg Nebula
Click for original image.

Cool image time! The picture to the right, reduced to post here, was taken by the Hubble Space Telescope as part of a study of “preplanetary nebula,” the initial stages of a planetary nebula that forms as some star types begin dying. From the caption:

Many preplanetary nebulae are relatively dim and hard to spot. They are made of layers of gas ejected by the star, but that star is not yet hot enough to ionise the gas and cause it to glow. The Egg Nebula is relatively unique, easily visible as a sparkling jewelled egg in space. Powerful beams of starlight blast out of the inner cloud, two a-side, giving a breathtaking illumination to this cosmic structure. Fast-moving outflows of hot molecular hydrogen also emerge from within the dust cloud, visible just at the base of the searchlight beams. These outflows glow with infrared light, which is shown in this image by orange highlights.

The central cloud of dust is surrounded by concentric rings, themselves made up from thin, faint arcs of gas. These were created by successive outbursts from the central star, which ejected a little more material from its outer surface every few hundred years. The beams of starlight are reflected by these layers of gas, creating an appearance like ripples on the surface of water. The way that gas molecules reflect and scatter light gives a bluish colour to the arcs. The reflected starlight reveals important details about the central star, which is impossible to view directly in its dusty shell.

Many planetary nebula get their spectacular shapes because they have a binary star system in their center, that act like the blades in a blender as they circle each other, mixing the materials the stars’ eject to form those shapes. Because of those surrounding shells, it is often impossible to determine with the nebula has a single central star, or a binary system.

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How Saturn’s moon Enceladus causes an aurora on Saturn

9:38 am

Enceladus orbiting Saturn
Click for original image.

Using data collected by the orbiter Cassini while it orbited Saturn more than a decade ago, scientists now think they have mapped out how the moon Enceladus interacts with Saturn’s magnetic field and helps create an aurora in Saturn’s polar regions.

You can read the paper here. The artist rendering to the right comes from the press release, and shows that interaction. From that release:

The study, published in the Journal of Geophysical Research: Space Physics, shows how wave structures, known as ‘Alfvén wings’, travel like vibrations on a string along magnetic field lines connecting Enceladus to Saturn’s pole. The initial ‘main’ Alfvén wing is reflected back-and-forth both by Saturn’s ionosphere and the plasma torus that encircles Enceladus’s orbit, resulting complex and structured system. By using a multi-instrumental approach, researchers were able to show that the influence of Enceladus extends over a record distance of over 504,000 km – more than 2,000 times the moon’s radius.

…As well as the large-scale structures, the team found evidence that turbulence teases out the waves into filaments within the main Alfvén wing. This fine-scale structure helps the waves bounce off Enceladus’s plasma torus and reach the high-latitudes in Saturn’s ionosphere where auroral features associated with the moon form.

The white haze below Enceladus in the graphic represents the material that comes out of the “tiger stripe” fractures near its south pole.

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A lava tube on Venus?

9:18 am

Theorized lava tube on Venus

The uncertainty of science: Scientists in Italy have reanalyzed the radar data of Venus by the Magellan orbiter from 1990 to 1992 and concluded that at least one open pit on the side of a shield volcano might be the entrance to a underground lava tube.

You can read their paper here [pdf]. The graphic above comes from figures 2 and 3 of their paper, with the radar image of the pit to the right, and the cartoon to the left their interpretation of that radar data. From the abstract:

Between 1990 and 1992, the Synthetic Aperture Radar (SAR) instrument on board the Magellan spacecraft mapped the Venusian surface. By leveraging a SAR imaging technique developed for detecting and characterizing accessible subsurface conduits in the proximity of skylights, we analysed
the Magellan radar images in locations where there is evidence of localized surface collapses. Our analyses reveal the existence of a large and open subsurface conduit in the Nyx Mons region. This feature is hypothesized to be a pyroduct, characterized by a diameter of about 1 km, a roof thickness of at least 150 m and an empty void height of no less than 375 m. The conduit extends in the subsurface for at least 300 meters from the skylight.

To strengthen their conclusions, which are based on a LOT of assumptions, the scientists also compared this radar data with radar data taken of similar-sized lava tube skylights on Earth.

Their conclusion is reasonable, as Venus is a planet of volcanoes, with more than a million detected in radar data. Lava tubes should exist. Nonetheless, their interpretation of the radar data is very uncertain, and must be viewed with a great deal of skepticism.

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India picks landing site for its Chandrayaan-4 lunar sample return mission

10:22 am

Landing sites at the Moon's South Pole

Scientists at India’s space agency ISRO have now picked [pdf] a preliminary landing site for its planned Chandrayaan-4 lunar sample return mission, scheduled to launch in 2028.

[Four] sites of Mons Mouton area was fully characterised with respect to terrain characteristics using high resolution OHRC multiview image datasets and it was found that 1km x 1km area around MM-4 (-84.289, 32.808) contains the less hazard percentage, mean slope of 5°, Mean height of 5334m and most number of hazard free grids of size 24m x 24m. Hence MM-4 can be considered for the potential site of Chandrayaan-4 mission.

The study area of all four sites is indicated on the map to the right by the red dot labeled “Chandrayaan-4”. This mountain, Mons Mouton, is essentially a flat plateau between the numerous craters in the south pole region (many with permanently shadowed craters). Intuitive Machines second lander, Athena, attempted a landing there last year, and tipped over, as did that company’s first lander, Odysseus, both indicated in green. Astrobotic’s Griffin lander (yellow) is targeting this mountain also, hopefully to launch later this year.

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One of Cassini’s first close-up images of Saturn’s rings

12:48 pm

The rings of Saturn
Click for original image.

Cool image time! My exploration of the Cassini image archive continues. The picture to the right, reduced and enhanced to post here, was taken on May 2, 2005 by Cassini soon after it moved into a close orbit of Saturn where it could get high resolution images of Saturn’s rings. This is one of the first.

This is also a raw image that has not been calibrated or validated, to use the science team’s terms. Thus, the white dots scattered across the image could be artifacts that need to be cleaned up, not examples of Saturn’s many moons.

Regardless, the image illustrates the incredible delicacy of these rings, despite the fact that they are gigantic, spanning almost 45,000 miles in width, with a thickness ranging from 30 to 1,000 feet. And yet, there are so many distinct rings they almost resemble an old-fashioned vinyl record.

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Pluto’s implausible atmosphere, as seen in 2015 by New Horizons

2:07 pm

Pluto's implausible atmosphere
Click for original image.

Cool image time! The picture to the right, cropped to post here, was taken on July 14, 2015 by the camera on the New Horizons probe as it flew past Pluto, the only time a human craft has gotten close to this distant planet. From the link:

These high phase angle images show many artifacts associated with scattered sunlight; the Sun was less then 15 degrees from the center of the LORRI frame for these observations. But the outline of Pluto and its hazy atmosphere are also visible.

To see the atmosphere the light from the planet itself has been blocked out.

What is implausible about Pluto’s atmosphere is the location of the planet, about 3.7 billion miles from the Sun, out in the nether reaches of the solar system. At that distance sunlight is very weak, and produces very little energy. And yet, there is enough energy here to produce an atmosphere of mostly nitrogen gas, with trace amounts of metane and carbon monoxide. Scientists think this atmosphere only exists when Pluto is closer to the Sun in its somewhat oblong orbit, and freezes out the rest of the time. As Pluto was just retreating in 2015 from that closest approach in the last two decades of the 20th century, New Horizons could detect its presence.

But then, we really can’t be sure if this atmosphere truly vanishes when the planet is farthest from the Sun, as we have only so far observed 96 years in Pluto’s 248-year orbit.

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Astronomers use SphereX infrared space telescope to study interstellar Comet 3I/Atlas

8:32 am

False color images of SphereX infrared data
False color images of SphereX infrared data.
Click for original.

Using NASA’s SphereX infrared space telescope, astronomers have now detected a range of new molecules in the coma surround interstellar Comet 3I/Atlas as that coma brightened and grew in December 2025 following the comet’s closest approach to the Sun in the fall.

You can read the research paper here. From the press release:

In a new research note, mission scientists describe the detection of organic molecules, such as methanol, cyanide, and methane. On Earth, organic molecules are the foundation for biological processes but can be created by non-biological processes as well. The researchers also note a dramatic increase in brightness two months after the icy body had passed its closest distance to the Sun, a phenomenon associated with comets as they vent water, carbon dioxide, and carbon monoxide into space.

In every way this interstellar object continues to behave like an ordinary comet, which is actually quite profound. It tells us the rest of the universe is not that different than our solar system.

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One of Saturn’s many weird moons

11:47 am

Saturn's moon Atlas
Click for original image.

Cool image time! The picture to the right, cropped and reduced to post here, was taken on April 13, 2017 by the orbiter Cassini as it began it last close loops around Saturn before diving into its atmosphere to burn up.

Those close loops allowed it to get good close-up images of a few of the tiny moons that orbit in or close to the gas giant’s rings. On the right is one of those pictures, of the moon Atlas, taken from a distance of about 10,000 miles.

The moon’s weird ravioli shape is thought to be caused by the accretion of dust and ice from the nearby rings along Atlas’s equator.

Scientists also found the moon surfaces to be highly porous, further confirming that they were formed in multiple stages as ring material settled onto denser cores that might be remnants of a larger object that broke apart. The porosity also helps explain their shape: Rather than being spherical, they are blobby and ravioli-like, with material stuck around their equators. “We found these moons are scooping up particles of ice and dust from the rings to form the little skirts around their equators,” Buratti said. “A denser body would be more ball-shaped because gravity would pull the material in.”

Atlas itself is about 25 miles wide and about 11.5 miles thick, at its thickest point. I suspect if you tried to walk on it you would sink into the accumulated dust and ice, as it is likely no more dense as newly fallen snow.

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Pluto and Charon come out of the dark

1:40 pm

Pluto and Charon come out of the dark
Click for original image.

Cool image time! I have decided to start delving into the archives of some of the older planetary missions, because there is value there that is often forgotten now years later, that should not be forgotten.

In looking through the archive of images from the main camera on New Horizons as it sped past Pluto in July 2015, I found the picture to the right, taken on July 10, 2015 when New Horizons was still about three million miles away.

This is the raw image from that camera, cropped, reduced, and sharpened to post here. It is also the first time in human history we had a sharp look at these two planets that sit at the outer fringes of the solar system. The science team that day released a version that they enhanced to bring out the details, which I immediately posted. They then noted the following:

A high-contrast array of bright and dark features covers Pluto’s surface, while on Charon, only a dark polar region interrupts a generally more uniform light gray terrain. The reddish materials that color Pluto are absent on Charon. Pluto has a significant atmosphere; Charon does not. On Pluto, exotic ices like frozen nitrogen, methane, and carbon monoxide have been found, while Charon’s surface is made of frozen water and ammonia compounds. The interior of Pluto is mostly rock, while Charon contains equal measures of rock and water ice. “These two objects have been together for billions of years, in the same orbit, but they are totally different,” said Principal Investigator Alan Stern of the Southwest Research Institute (SwRI), Boulder, Colorado.

This difference is quite clear in the raw image, with Charon markedly dimmer than Pluto even though they are getting the same amount of light from the Sun.

More than any other objects in the solar system, the double planet system of Pluto-Charon demonstrates how uniquely different every object in the solar system is from every other object. Even when formed together, as these two planets were, they formed in a manner that made them drastically different.

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A galaxy’s swirling dust lanes

12:07 pm

A galaxy with swirling dust lanes
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken by the Hubble Space Telescope as part of follow-up observations of a now faded supernovae that occurred there two years earlier.

This was on purpose: the aim of the observations was to witness the aftereffects of the supernova and examine its surroundings, which can only be done once the intense light of the explosion is gone.

The galaxy itself, NGC 7722, is 187 million light years away, and is unusual in itself.

A “lenticular”, meaning “lens-shaped”, galaxy is a type that sits in between the more familiar spiral galaxies and elliptical galaxies. It is also less common than these — partly because when a galaxy has an ambiguous appearance, it can be hard to determine if it is actually a spiral, actually an elliptical galaxy, or something in between. Many of the known lenticular galaxies sport features of both spiral and elliptical galaxies. In this case, NGC 7722 lacks the defined arms of a spiral galaxy, while it has an extended, glowing halo and a bright bulge in the center similar to an elliptical galaxy. Unlike elliptical galaxies, it has a visible disc — concentric rings swirl around its bright nucleus. Its most prominent feature, however, is undoubtedly the long lanes of dark red dust coiling around the outer disc and halo.

The streak in the lower left is a very distant background galaxy, seen on edge.

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Comet K1/Atlas has broken apart, not interstellar Comet 3I/Atlas

10:37 am

the end of Comet K1/Atlas

CORRECTION: The image to the right is not that of interstellar Comet 3I/Atlas, as I reported earlier today. I misread the Gemini Telescope release. This is comet K1/Atlas, another comet from our own solar system that made its close approach to the Sun in October, when it broke up.

The the latest image from the Gemini North Telescope in Hawaii shows at least four sections slowly drifting apart.

The picture to the right, cropped to post here, was taken on December 6, 2025. Gemini’s previous image, taken in November 11th, shows about the same number of objects, but clustered much more closely together.

It appears that as the comet made its closest approach, the stress was too great. This is not surprising, as it happens to many comets that get too close to the Sun.

Sorry for the error and hat tip to reader Tom Laskowski for letting me know. I need to look at the names of comets named after the ATLAS telescope, as they are very similar and most are NOT interstellar comet 3I/Atlas.

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Pluto’s mountains of ice surrounded by a sea of frozen nitrogen

2:18 pm

Ice mountains floating in nitrogen sea on Pluto
Click for original image.

Cool image time! Though we only have a limited archive of high resolution pictures of Pluto that were taken when New Horizons did its close fly-by of the planet in July 2015, it is worthwhile sometimes to take a second look at some of those images. The picture to the right, cropped and annotated to post here, was taken during that July 14, 2015 fly-by, and shows a mountainous region dubbed Al-Idrisi Montes on the shore of a white frozen ocean. The red dotted line indicates a large trench that separates the Al-Idrisi mountains from the mountainous region to the west.

Sounds similar to an arctic shoreline here on Earth, doesn’t it? Not in the least. Those mountains, ranging from 600 to 9,000 feet high, are made of frozen ice, which on Pluto are as hard as granite due to the endless cold. And the white frozen ocean is frozen nitrogen, broken into polygon shaped blocks. Even stranger: those ice mountains might even be floating in that nitrogen sea! A paper from 2019 [pdf] looked at the New Horizons data and concluded as follows:

Evidence suggests that the Al-Idrisi mountains may have been uplifted by the formation of
the western trench feature. Solid state convection appears to be our best supposition as to how the Al-Idrisi Montes reached their heights.

In other words, as that large trench/depression formed, convection (the bubbles you see when you simmer tomato sauce) pushed these mountains of ice upward to float above the “sea level” of that nitrogen sea.

At least, that’s one hypothesis. The scientists who wrote this paper admit their “our hypothesis still remains in need of study and this trench-mountain system warrants serious further research.” In other words, we simply don’t know enough to have a definitive understanding of the geology of this extremely alien planet.

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Saturn’s rings with two of its moons perfectly aligned

2:30 pm

Two of Saturn's moons above its rings
Click for original image.

Cool image time! Rather than posting another Mars orbital image, I decided today to delve into the archive of pictures taken by the Cassini orbiter during the thirteen years it circled Saturn, from 2004 until 2017. The picture to the right, cropped to post here, was released on December 14, 2015, and is just one example of the many breath-taking photographs that the Cassini science team took during that mission. From the caption:

Like a cosmic bull’s-eye, Enceladus and Tethys line up almost perfectly for Cassini’s cameras. Since the two moons are not only aligned, but also at relatively similar distances from Cassini, the apparent sizes in this image are a good approximation of the relative sizes of Enceladus (313 miles across) and Tethys (660 miles across).

This view looks toward the un-illuminated side of the rings from 0.34 degrees below the ring plane. The image was taken in red light with the Cassini spacecraft narrow-angle camera on Sept. 24, 2015.

The image was obtained at a distance of approximately 1.3 million miles from Enceladus. Image scale on Enceladus is 7 miles per pixel. Tethys was at a distance of 1.6 million miles with a pixel scale of 10 miles per pixel.

Enceladus is in the foreground, and is the planet that has what scientists have labeled tiger stripe fractures that vent water and other material, including carbon molecules.

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Astronomers discover a “surprisingly mature” cluster of galaxies in early universe

11:18 am

Proto galaxy cluster
Click for original image.

The uncertainty of science strikes again! Astronomers using both the Webb Space Telescope and the Chandra X-ray Observatory now think they have discovered a just-forming protocluster of galaxies only one billion years after the Big Bang, when such galaxy clusters should not yet exist.

You can read their paper here [pdf]. The image to the right, cropped and reduced to post here, shows the Webb infrared data as the background of stars and galaxies, with the galaxies thought to be part of this protocluster circled. The blue cloud is Chandra’s X-ray data. From the press release:

The Chandra and Webb data reveal that JADES-ID1 contains the two properties that confirm the presence of a protocluster: a large number of galaxies held together by gravity (Webb sees at least 66 potential members) that are also sitting in a huge cloud of hot gas (detected by Chandra). As a galaxy cluster forms, gas falls inward and is heated by shock waves, reaching temperatures of millions of degrees and glowing in X-rays.

What makes JADES-ID1 exceptional is the remarkably early time when it appears in cosmic history. Most models of the universe predict that there likely would not be enough time and a large enough density of galaxies for a protocluster of this size to form only a billion years after the big bang. The previous record holder for a protocluster with X-ray emission is seen much later, about three billion years after the big bang.

It increasingly appears that there are aspects of the universe we simply do not yet understand, which in turn make our theories of its birth and formation either incomplete or invalid. Those theories might be right in principle, but the data suggests they are wrong in detail.

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Webb finds another unexpected galaxy in the very early universe

9:25 am

Unexpected galaxy
Click for original image.

The uncertainty of science: Using the Webb Space Telescope, astronomers have discovered another galaxy in the very early universe that appears too bright and developed for it to even exist so soon after the Big Bang.

MoM-z14 is one of a growing group of surprisingly bright galaxies in the early universe – 100 times more than theoretical studies predicted before the launch of Webb, according to the research team. “There is a growing chasm between theory and observation related to the early universe, which presents compelling questions to be explored going forward,” said Jacob Shen, a postdoctoral researcher at MIT and a member of the research team.

…With galaxy MoM-z14 existing only 280 million years after the big bang, there was not enough time for generations of stars to produce such high amounts of nitrogen in the way that astronomers would expect. One theory the researchers note is that the dense environment of the early universe resulted in supermassive stars capable of producing more nitrogen than any stars observed in the local universe.

All theories about the Big Bang and the early universe did not predict the existence of this galaxy, or a bunch of others that Webb has now detected.

The false color infrared Webb image is to the right, cropped and reduced to post here. The full image covered a much larger area, so this tiny galaxy was not easy to find. Scientists identified it by the very high red shift of its light, due to the expansion of the universe and it being so far away. That expansion away from us causes the wavelengths of its light to stretch into the infrared so that only Webb can see it.

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Scientists produce new estimate of the thickness of Europa’s icy crust

5:23 pm

Europa in true color
Europa in true color, taken by Juno during that
September 2022 fly-by. Click for full image.

Using data produced by Juno during a 2022 close-fly of Jupiter’s moon Europa, scientists have made a new estimate of the thickness of Europa’s icy crust, approximately 18 miles thick with a 6-mile margin of error.

In other words, their estimate could be as small as 12 miles thick, or as large as 24 miles thick.

You can read their paper here. From their abstract:

For the idealized case of pure water ice, the data are consistent with the existence of a thermally conductive ice shell with a thickness of 29 ± 10 km [18 ± 6 miles] and with the presence of cracks, pores or other scatterers extending to depths of hundreds of metres below the surface with a characteristic size smaller than a few centimetres in radius. An ice-shell salinity of 15 mg kg−1, as indicated by models based on terrestrial marine ice, would reduce our estimate of the thickness of the ice shell by about 5 km, substantially less than our 10 km uncertainty. The low volume fraction, small size and shallow depth of the scatterers indicate that the fracture interfaces observed at Europa’s surface are alone unlikely to be capable of carrying nutrients between the surface and the ocean. [emphasi mine]

The highlighted sentence is the important one. If this new estimate is right, than the unidentified reddish material that appears to leak out of the long ridgelike cracks on Europa’s surface, clearly visible in the picture to the right, are not coming from any underground ocean. The distances are too large.

Other estimates have suggested that ice crust could be as thin as 2 miles, but like this research the uncertainties are very large.

Meanwhile, the Juno mission is still alive, though essentially winding down operations. The mission was expected to officially end at the end of September 2025, when its budget ran out, but the just passed budget included enough money to keep it going, albeit at a relatively low level. According to the orbiter’s webpage, it will continue to orbit Jupiter, its orbit degrading naturally until it falls into Jupiter to burn up. As it does so data will continue to be collected, though at a much lower rate.

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Windswept Martian volcanic ash?

2:35 pm

Volcanic ash on Mars?
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on November 30, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this simply as “Features,” the vagueness of which I can understand after digging in to get a better idea of the location and geography.

The location, as shown by the white dot on the overview map below, is inside the Medusa Fossae Formation, the largest volcanic ash field on Mars that is thought to be the source of much of the red planet’s dust. That ash field is large and very deep, and was put down more than a billion years ago when the giant volcanoes of Mars were active and erupting. Thus it is well layered, and many images of that ash field show that layering exposed by the eons of Martian wind scouring its surface.

In this case, that scouring appears to have produced this feathery surface, though the origin of those ridges might have instead come from volcanic flows that are now hardened. Or we could be looking at ancient channels produced by ice or water, though that would have to have been a very long time ago, as this image is located in the Martian dry tropics, where no near surface ice presently exists.
» Read more

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Astronomers use AI to discover hundreds of weird galaxies in Hubble archive

10:23 am

Weird galaxies in the Hubble archive, found with AI
Click for original image.

In what is a perfect example of the proper use of artificial computer intelligence (AI), astronomers have now used this programming to analyze almost 100 million images taken by the Hubble Space Telescope over the decades to find any galaxies hidden there that have “anomalies” or unusual shapes.

The team analyzed nearly 100 million image cutouts from the Hubble Legacy Archive, each measuring just a few dozen pixels (7 to 8 arcseconds) on a side. They identified more than 1,300 objects with an odd appearance in just two and a half days — more than 800 of which had never been documented in scientific literature.

The six galaxies to the right are just a small sample. All six were previously unidentified, and include “three lenses with arcs distorted by gravity, one galactic merger, one ring galaxy, and one galaxy that defied classification” (the galaxy at the top left). From the European Space Agency’s (ESA) press release:

The strange, bi-polar galaxy seen here is certainly anomalous, with its compact, swirling core and two open lobes at the sides. Exactly what kind of galaxy it is is unclear, and it was not previously known to astronomers.

As noted in the first link, the volume of data that astronomers are now collecting from ground-based and orbiting telescopes — many of which are survey telescopes that photograph the entire sky repeatedly — has actually become a problem. They have great data, but don’t have the time or human resources to study it sufficiently. Even employing large numbers of ordinary citizens, working at home with their own computers, can’t get the job done.

This is the kind of grunt work that AI is ideally made for. It can quickly review the data and identify objects that don’t fit normal expectations. Humans then can do the real work, finding the most interesting of these strange objects, such as the top left galaxy, and devote human creativity to studying it.

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