Tag: geology

Corroding glacial features inside Martian crater

11:25 am

Overview map
Glacier country in the Martian northern mid-latitudes.

The corroding glacial floor of a Martian crater
Click for original image.

Today’s cool image gives us another nice example of the ample availability of near surface ice on Mars, even if it might take a bit of processing to extract it from the dust and soil. The picture to the right, rotated, cropped, and reduced to post here, was taken on March 31, 2026 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The picture captures in detail most of the floor of a 5.8-mile-wide unnamed crater, located in the northern mid-latitudes of Mars, in a 2000-mile-long strip I like to call glacier country, because practically every image taken there shows extensive glacial features. The white dot on the overview map above shows the location within that strip, with the inset showing the full crater, as well as the surrounding terrain.

The softness of this landscape strongly suggests a topsoil well impregnated with ice. The crater’s rim is itself very soft and subdued, suggesting melting and sublimation over time.

The material in the floor of the crater resembles peeling paint, which in this case suggests the ice there has been sublimating away as well. Nonetheless, there remains a lot under the surface. Future Martian colonists will certainly come to this region to gather ice for their own purposes.

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Curiosity looks closely at the broken slab that had been stuck on its drill bit

12:37 pm

The rock Atacama
Click for original image.

As expected, the science team for the Mars rover hasdecided before moving on it would take a close look at the 28 pound slab of rock that had been stuck on its drill bit and when finally dropped free broken into several pieces when it hit the ground.

The top picture to the right, cropped and reduced to post here, shows that entire rock, labeled Atacama by the science team. The two insets below are close-ups of the delicate layering at the rock’s left edge as well as the drill hole itself. From team’s update today:

The highest-priority activities after liberating the drill included imaging the drill with Mastcam and ChemCam RMI, and imaging into the now-empty drill hole with MAHLI (the image above). The science team made the most of the freshly-broken surfaces created when Atacama fell back to Mars, and the freshly-exposed sand once hidden underneath Atacama.

The exposed sand is off camera, to the right. Expect a paper published about that sand, buried likely for millions of years, sometime in the next year or so.

The delicate flutes at the rock’s left edge are somewhat common rock features seen by Curiosity, made possible by Mars’ thin atmosphere and its one-third Earth gravity. On Earth the gravity and weather generally destroys such things. On Mars the lack of violent weather and light gravity allows them to form, and the thin wind even helps in their formation.

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Springtime on the residual icecap of the Martian south pole

11:42 am

Weird hatchwork at the Martian south pole
Click for original image.

Cool image time! The picture to the right, cropped and rotated so that north is to the top, was taken on March 28, 2026 by the high resolution camera of Mars Reconnaissance Orbiter (MRO).

It shows what the science team labels a “south polar residual cap site.” The location is about 200 miles from the Martian south pole, well within the south polar ice cap. A second picture of this same spot was taken only a few days later, and was labeled “bright and dark fans on patterned ground.” With the second image the science team added their nickname for this location, “Troy,” which makes referencing it easier.

The hatchwork is the mystery here. In fact, the scientists have been monitoring this geology since 2020 to see if there have been any changes, either long term or seasonally. Almost certainly they have spotted seasonal changes, as indicated by the hatchwork itself and explained below, but I don’t access to the higher resolution images that would show any major modifications on a larger scale.
» Read more

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Juno flies past the Jupiter moon Thebe

11:07 am

Jupiter's moon Thebes
Click for original image.

Though the Jupiter orbiter Juno is in its final orbits as it is running out of fuel, on May 1, 2026 it did a close fly-by of the 50 by 72 mile-wide Jupiter moon Thebe, getting within 3,100 miles.

The picture to the right, cropped and expanded to post here, is the best image released from that fly-by. It is very comparable to a photo taken by the Galileo orbiter on January 4, 2000. Both show the very large crater, dubbed Zethus.

The picture was taken by Juno’s Stellar Reference Unit (SRU) camera, designed not to do science but to “image star fields for navigation.” Thus, the picture is somewhat fuzzy, and was pointed poorly so the moon is on the far right, almost off camera.

It is very unclear how much longer Juno will function. It has apparently survived attempts by the Trump administration to zero out its operating budget, but there have been indications that its fuel supply is low.

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Curiosity unintentionally picks up a rock slab

11:15 am

Sequence showing slab picked up and then dropped
Click for movie. Original images found here, here, here, and here.

In their latest drilling campaign using the drill on the Mars rover Curiosity, the science team picked up a big surprise that could have been a serious problem, but turned out all right in the end. When they tried to extract the drill from the hole, the drill instead stayed stuck to the rock, and picked the whole rock up instead.

The four images to the right show the sequence, sourced from here, here, here, and here.

On April 25, 2026, Curiosity drilled a sample from a rock nicknamed “Atacama,” which is an estimated 1.5 feet in diameter at its base, 6 inches thick and weighs roughly 28.6 pounds (13 kilograms). When the rover retracted its arm, the entire rock lifted out of the ground, suspended by the fixed sleeve that surrounds the rotating drill bit. Drilling has fractured or separated the upper layers of rocks in the past, but a rock has never remained attached to the drill sleeve. The team initially tried vibrating the drill to shake off the rock, but saw no change.

Then, on April 29, they tried reorienting Curiosity’s robotic arm and vibrating the drill again. Imagery in the GIF shows sand falling from Atacama, but the rock stayed attached to the rover.

Finally, on May 1, Curiosity’s team tried again, tilting the drill more, rotating and vibrating the drill, and spinning the drill bit. The team planned to perform these actions multiple times but the rock came off on the first round, fracturing as it hit the ground.

Had they not been able to release the rock it could have seriously impacted the mission, even ended it.

As noted by the science team in their own update today about this situation:

Future activities involve wrapping up the drill campaign on Atacama and, nominally, seeking a more firmly rooted drill target in order to collect drill tailings for analysis, which were lost from Atacama as part of the effort to dislodge the drill bit from the rock.

In other words, they are going to have hunt around for a better drill spot, as they really do want to study some drill samples at this location. They have left the boxwork area and have moved uphill closer to the pure sulfite unit, and want to see how the geology has changed.

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Curiosity looks at a small crater as it climbs Mount Sharp

11:50 am

Antofagasta crater
Click for full resolution. Click here, here, and here for original images.

Cool image time! The panorama above, created from three pictures taken by the right navigation camera on the Mars rover Curiosity (see here, here, and here), takes a look at a small relatively fresh crater on the slopes of Mount Sharp. From an update from the rover’s science team yesterday:

At the beginning of the week, Curiosity arrived right on target on the rim of the 10-meter (33 feet) “Antofagasta” crater. The crater looked fresh and deep as we had hoped with a nice well-defined rim that didn’t look too eroded, but the bottom of it turned out to be filled with dark rippled sandy material that covered up the most interesting rock layers. There were a few rock exposures just above the sand cover that seemed like they might have been deep enough to have been sheltered from space radiation between the time their sediments were deposited and the crater-forming impact, but reaching them from the rim would have put the rover at such an awkward angle that we wouldn’t have been able to deliver the sample to the instruments.

Overview map
Click for interactive map.

It’s possible that we might have been able to get into a better position by instead placing the rover on the rippled crater fill, but the chance that the rover could get stuck in all that sand made it much too high a risk. We also looked at the nearby blocks in case they could have been ejecta from the crater, but since all the rocks visible in the crater wall looked very similar to each other, there wasn’t a good way to tell which ejecta blocks might have come from the deeper layers of the crater. Because of this, the team decided against attempting to drill in or around the crater.

The overview map to the right provides the context. The blue dot marks Curiosity’s location when the pictures above were taken. The yellow lines roughly indicate the area covered by the panorama. The red dotted line marks the future planned route, the white dotted line the rover’s actual travels.

Note the flat rocks in the foreground of the panorama, all part of the crater’s rim. Each looks like a large flat paving stone that was very precisely shattered into numerous tiny pieces, all about the same size. Very strange. On Earth you’d assume some craftsman had laid these small pieces down like tiles, but of course, that couldn’t have happened on Mars.

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The movement of surface ash on Mars over a half century

12:08 pm

Viking and Mars Express images side-by-side for comparison
Go here and here for original images.

Overview map

Cool image time! In comparing images of one location on Mars taken a half century apart, scientists using Europe’s Mars Express orbiter have discovered that the dark ash covering this region has shifted south by about 200 miles.

The two images above show the change, with a Viking orbiter image taken sometime in 1976 on the left and the Mars Express image taken in 2026 on the right. Both images have been enhanced to match each other, with the white box marking an area seen in close-up by Mars Express.

The overview map to the right provides the context. This region is inside Utopia Basin, one of the largest ancient impact basins on Mars, thought to have been formed by an impact that occurred a little more than four billion years ago. Much of Mars’ dark volcanic dust is thought to come from the Medusae Fossae Formation, a gigantic volcanic ash field the size of India and located on the other side of the planet, in between all of the red planet’s largest volcanoes. Over the eons that ash has gotten distributed across the globe.

In this case, it not only covers large areas of Utopia Basin, but over a half century the prevailing winds in the thin Martian atmosphere has been enough to shift the edge of this particular ash field south by 200 miles.

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Martian mountains on Mount Sharp

11:45 am

Panorama looking up Mount Sharp
Click for larger full resolution image. For original images go here and here.

Overview map
Click for interactive map.

Cool image time! The panorama above was created using two pictures taken by the high resolution camera on the rover Curiosity on Mars (here and here).

The overview map to the right gives the context. The blue dot marks Curiosity’s position on the day before these pictures were taken, climbing through the foothills on the flanks of Mount Sharp. I do not know if it traveled again before taking these two pictures above. The white dotted line its past travels, while the red dotted line its planned future route. At present Curiosity has climbed about 3,500 feet up the mountain. It is still about 15,000 feet below the peak, which is about 25 miles away and not visible from here.

The yellow lines indicate where I think the panorama is looking, though I admit that I am not sure. The view is distant, since this is high resolution camera. This panorama might actually be looking in a completely different direction, downhill at one of the hills that Curiosity previously drove past. The air is very dusty, which means if the rim of Gale Crater is in the background, 20-30 miles away, we can’t see it.

Regardless, the science team has finally finished its many nine-month-long survey of the boxwork geology, and has sent Curiosity climbing again. I think these pictures are part of their review of the future terrain, as they plan the rover’s route through the lighter-colored sulfate terrain higher on the mountain. If instead they are looking downhill, they were taken both to review previously viewed geology as well as to measure the dustiness of the atmosphere.

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Feathery eroding layers on Mars

11:01 am

Feathery layers on Mars
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was taken on February 23, 2026 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows what the science team calls “layers exposed around [a] streamlined feature”.

The elevation difference between the mesa top on the left and the canyon floor on the right is about 1,000 feet. The layers are the terraces stepping downward along that drop.

What makes these layers interesting is how they have been exposed. The material that makes up the layers appears very sandy and delicate, so it breaks away it very small pieces, just like sand on a beach. The result is this feathery look. If you look close you can see that some small craters have been partly obliterated by that erosion, with their existence only marked by their remaining rim, on the high side.
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Cracked bedrock on Mars?

2:01 pm

Cracked Martian landscape
Click for full image.

For today’s cool image we return to Mars. The picture to the right, cropped and brightened to post here, was taken on December 3, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The focus of the picture was a strange crater in the floor of Mawrth Vallis, a channel that drains northward from Mars’ cratered southern highlands to its northern lowland plains. You can see the crater in the full image if you click on the picture. It is intriguing because its rim is strangely abrupt and flat on all sides, something that is not seen with impact craters, which have a raised rim of material plowed out by the impact.

In the picture to the right I have however focused on the two small 50-70-foot-high mesas and cracked ground that surrounds them. What struck me was the dry appearance of this landscape. Located at 23 degrees north latitude, it is in the dry tropics of Mars, where little near surface ice is found. The cracks emphasize this conclusion, as they so well resemble the cracks you see in dried mud on Earth.
» Read more

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Proteus, Neptune’s second largest moon, discovered by Voyager-2 in 1989

3:02 pm

Proteus, Neptune's second largest moon
For original images go here and here.

Our tour continues of the only close visit to Neptune on August 25, 1989 by Voyager-2. The two pictures to the right were taken by the spacecraft during that fly-by of Neptune’s second largest moon, dubbed Proteus. Both pictures are shown as Voyager-2 took them.

The top picture was taken from a distance of about 540,000 miles, and has a resolution of about five miles per pixel.

The satellite has an average radius of about 120 miles and is uniformly dark with an albedo of about 6 percent. The irregular shape suggests that 1989N1 has been cold and rigid throughout its history and subject to significant impact cratering.

The bottom picture was taken from a distance of about 91,000 miles, and can resolve objects as small as 1.7 miles in size.

Hints of crater-like forms and groove-like lineations can be discerned. The apparent graininess of the image is caused by the short exposure necessary to avoid significant smear.

Proteus was not known prior to Voyager-2’s fly-by, because it orbits so close to Neptune (about 73,000 miles) that the ground-based telescopes of the time could not see it in the glare of the gas giant. It was discovered in early global pictures of Neptune as Voyager-2 approached.

While planetary scientists have made some educated guesses about the moon’s origin and geology based on these two images, they are simply guesses. These are the only detailed images we have of Proteus, and neither is particularly good.

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Triton: Neptune’s largest moon

11:19 am

The southern mid-latitudes of Neptune's moon Trident
Click for original image.

Triton

Today’s cool image begins a new tour I plan on doing over the next week or so of the few close-up photographs we have of Neptune and its moons, sent back by Voyager-2 when it did its close fly-by of this distant planet on August 25, 1989. That fly-by was almost 37 years ago, and it remains our only close look. While at the time it shined a quick flashlight of new knowledge on Neptune, its moons, and its ring system, we remain generally in the dark about what’s there, despite some good imagery produced in subsequent years by Hubble and some ground-based telescopes.

The image above, cropped and enhanced to post here, shows a portion of the southern mid-latitudes of Triton, Neptune’s largest moon, as Voyager-2 made its closest pass at a distance of about 25,000 miles. The photo to the right, cropped and reduced, shows a more global view to provide some context, with the box indicating the approximate area covered by the upper image. It was taken when Voyager-2 was on approach, at a distance of about 330,000 miles. The top picture captures several dozen black plumes that appear to vent material from below. From the caption:

The plumes originate at very dark spots generally a few miles in diameter and some are more than 100 miles long. The spots which clearly mark the source of the dark material may be vents where gas has erupted from beneath the surface and carried dark particles into Triton’s nitrogen atmosphere. Southwesterly winds then transported the erupted particles, which formed gradually thinning deposits to the northeast of most vents.

It is possible that the eruptions have been driven by seasonal heating of very shallow subsurface deposits of volatiles, and the winds transporting particles similarly may be seasonal winds. The polar terrain, upon which the dark streaks have been deposited, is a region of bright materials mottled with irregular, somewhat dark patches. The pattern of irregular patches suggests that they may correspond to lag deposits of moderately dark material that cap the bright ice over the polar terrain.

As we only have a few images of this planet, and those provided views of only about 40% of its surface, any theory that tries to explain the weird geology here is certain to be wrong to some degree.

More to come in the next few days. As much as we think we know, these pictures are going instead highlight how sparse that knowledge really is.

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Growing damage to the wheels of the Curiosity Mars rover

9:19 am

Close-up of the wheel in the worst condition
Images cropped and reduced to post here. For the original images go here and here.

Survey of wheels

Every few months or so the Curiosity science team uses one of the rover’s cameras to do a survey of the rover’s wheels to track their condition. Since early in the mission they had found the wheels were not holding up as well as expected as they rolled over the rough terrain in Gale Crater and on Mount Sharp, and so they take great care in how they move the rover as well as review the wheels regularly.

A year ago it had appeared that the damage to one particular wheel had increased, to a point where its outer section might even break off.

Yesterday the science team did another survey, as shown in the picture to the right.

The two photos above (found here and here) focus on one particular wheel of that survey, which I suspect is the same wheel that was the focus of last year’s post. After taking the first image on the left the team moved Curiosity so that the other side of the wheel could be photographed. As you can see, the damage is extensive, so much so that it is possible the wheel could collapse entirely in the not-to-distant future.

It also looks like another wheel is beginning to see similar damage (see here and here), though not yet as extreme.

The good news is that Curiosity has six wheels, and that it can continue to travel even with the loss of one or maybe two wheels. It also appears that future terrain might not be so rocky.

The bad news is that this wheel damage is likely the one problem that will likely end the mission, possibly sooner than anyone would like. And from these photographs, that end might be sooner rather than later.

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Tantalizing Titania, Uranus’s largest moon

11:45 am

Uranus' five biggest moonsThe historically known moons of Uranus. Click for original NASA press release.

Titania as seen by Voyager-2
Click for original image.

This week’s tour of the five largest moons of Uranus continues today with a look at the highest resolution picture taken Uranus’s largest moon, Titania, when Voyager-2 did its fly-by of the solar system’s seventh planet on January 24, 1986. The image to the right, cropped and reduced to post here, was taken from about 229,000 miles, and can only resolve objects bigger than eight miles across. From the press release:

Titania is the largest satellite of Uranus, with a diameter of a little more than 1,000 miles. Abundant impact craters of many sizes pockmark the ancient surface. The most prominent features are fault valleys that stretch across Titania. They are up to 1,000 miles long and as much as 45 miles wide. In valleys seen at right-center, the sunward-facing walls are very bright. While this is due partly to the lighting angle, the brightness also indicates the presence of a lighter material, possibly young frost deposits. An impact crater more than 125 miles in diameter distinguishes the very bottom of the disk; the crater is cut by a younger fault valley more than 60 miles wide. An even larger impact crater, perhaps 180 miles across, is visible at top.

Two or three other images were taken by Voyager-2, but they don’t provide any significant additional information. All told the spacecraft was only able to see about 40% of Titania’s surface.

Subsequent research using a variety of orbiting telescopes have suggested there is water ice and carbon dioxide on the surface. This data also hints of the presence of a very very thin atmosphere. These results however are quite uncertain.

As with Uranus’s other moons Miranda, Ariel, and Umbriel that I highlighted earlier this week, the Voyager-2 data merely gives us a taste of what’s there. Forty years later we have learned almost nothing more about these distant worlds.

Tomorrow we look at Oberon. I will then follow-up the next day with a look at what we don’t know about Uranus and its moons.

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Scientists detect the five chemicals that make up DNA/RNA inside Ryugu samples

11:05 am

Ryugu's northern hemisphere
Ryugu as seen by Hayabusa-2 shortly before it grabbed
samples from the surface. Arrow indicates planned touchdown
site.

Scientists studying the samples brought back from the asteroid Ryugu by Japan’s probe Hayabusa-2 have found therein a full set of the five fundamental chemicals that make up either DNA or RNA: adenine, guanine, cytosine, thymine and uracil. From the paper’s [pdf] abstract:

Organic molecules delivered from extraterrestrial materials may have played a key role in supplying building blocks for life on Earth. Here we report all five canonical nucleobases—purines (adenine and guanine) and pyrimidines (cytosine, thymine and uracil)—in samples returned from the C-type asteroid (162173) Ryugu by JAXA’s Hayabusa2 mission and compare the results with data from similar extraterrestrial material.

Ryugu samples contain nearly equal amounts of purines and pyrimidines, whereas Murchison is enriched in purines and Bennu and Orgueil in pyrimidines. Samples from Ryugu, Bennu and Orgueil, which have a similar mineralogy and elemental composition, show purine-to-pyrimidine ratios negatively correlating with ammonia.

These observations indicate that the nucleobases in these samples may have formed via a shared pathway depending on the physicochemical environment of the respective parent bodies. The detection of diverse nucleobases in asteroid and meteorite materials demonstrates their widespread presence throughout the Solar System and reinforces the hypothesis that carbonaceous asteroids contributed to the prebiotic chemical inventory of early Earth.

In other words, the data from these samples suggests that the formation of life on Earth was greatly aided by the deposition of these carbon molecules from asteroids onto the Earth.

At the same time, some caution must be exercised. At present we only have samples from three asteroids, one of which (Orgueil) was obtained shortly after it crashed on Earth. It will take a much larger census of many in-space asteroids to confirm this hypothesis.

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Miranda, the smallest of Uranus’ spherical moons

12:52 pm

Miranda as seen by Voyager-2
Click for original image.

Cool image time! The image to the right, reduced and sharpened to post here, was created from photographs taken on January 24, 1986 by Voyager-2 as it made its fly-by of the gas giant Uranus. From a later 1996 release:

Miranda, roughly 300 miles in diameter, exhibits varied geologic provinces, seen in this mosaic of clear-filter, narrow-angle images from Jan. 24, 1986. The images were obtained from distances of 18,730 to 25,030 miles; resolution ranges from 1,840 to 2,430 feet. These are among the highest-resolution pictures that Voyager has obtained of any of the new “worlds” it has encountered during its mission.

On Miranda, ridges and valleys of one province are cut off against the boundary of the next province. Probable compressional (pushed-together) folded ridges are seen in curvilinear patterns, as are many extensional (pulled-apart) faults. Some of these show very large scarps, or cliffs, ranging from 1,600 feet to 3 miles in height — that is, higher that the walls of the Grand Canyon on Earth.

This is really the only close look we have of this distant world. The other hemisphere remains a mystery, as it was in darkness when Voyager-2 zipped past. And though some of the individual shots that make up this mosiac are more detailed, they don’t provide that much more information.

Nonetheless, to my uneducated eye Miranda looks like a ball of thick molasses that some giant stirred a bit as gravity forced it to settle into its spherical shape. In this case the molasses is likely a mix of ice and other materials, not yet fully identified. The result is a tiny misshapen planet with some of the roughest topography known in the solar system, including one 12-mile high cliff face (the white streak at the image bottom) thought to be the highest in the solar system.

We don’t yet have a true understanding of the geological processes that formed this strange landscape, nor will we have until we have a lot more data, including a global map of the entire surface. And that won’t come until a spacecraft is sent there to look more closely. Right now no such mission is in the works. No NASA missions have been funded, though several have been proposed. And a Chinese mission was apparently canceled last year.

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A close-up of the dark side of Saturn’s moon Iapetus

11:55 am

Iapetus' equator ridge
Click for original image.

Cassini's first global close-up of Iapetus
Click for original image.

Today’s cool image is a double-header! The picture above, cropped to post here, was taken on September 10, 2007 during Cassini’s fly-by of Saturn’s moon Iapetus, taken from approximately 1,000 miles above the surface. It looks at the dark side of this two-toned planet (see yesterday’s cool image). As the moon’s rotation is tidally locked so that one side always faces Saturn, one hemisphere always leads while the other always trails. For some reason still unexplained, the leading hemisphere is covered with an almost pitch-black material, while the trailing hemisphere is bright and very white, its icy surface quite visible.

For context, to the right is a global image of that dark side taken during Cassini’s first fly-by of Iapetus on December 31, 2004. This picture highlights the long ridge that runs along the planet’s dark hemisphere’s equator that was the focus of the close-up image above. From the 2005 press release:

The most unique, and perhaps most remarkable feature discovered on Iapetus in Cassini images is a topographic ridge that coincides almost exactly with the geographic equator. The ridge is conspicuous in the picture as an approximately 12 miles band that extends from the western (left) side of the disc almost to the day/night boundary on the right. On the left horizon, the peak of the ridge reaches at least 8 miles above the surrounding terrain. Along the roughly 800-mile-length over which it can be traced in this picture, it remains almost exactly parallel to the equator within a couple of degrees. The physical origin of the ridge has yet to be explained. It is not yet clear whether the ridge is a mountain belt that has folded upward, or an extensional crack in the surface through which material from inside Iapetus erupted onto the surface and accumulated locally, forming the ridge.

Iapetus itself has a diameter of about 900 miles, so this ridge essentially crosses most of the dark hemisphere.

The 2007 press release did not provide enough information to pinpoint exactly where along that ridge the close-up is located, but no matter. Both images make very clear what we are looking at.

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Iapetus: Saturn’s ying-yang moon

11:55 am

Iapetus as seen by Cassini in 2007
Click for original image.

Cool image time! The image to the right, reduced and sharpened to post here, was taken on September 10, 2007 by the Saturn orbiter Cassini as it made its first close fly-by of the moon Iapetus, from a distance of about 45,000 miles.

Iapetus, about 912 miles in diameter, is one of the strangest objects in the solar system. As it orbits Saturn, its leading hemisphere is very dark, covered with almost pitch black material, while its trailing hemisphere is very bright. This picture captures a bit of both, with the dark leading hemisphere visible along the right edge.

In many places, the dark material–thought to be composed of nitrogen-bearing organic compounds called cyanides, hydrated minerals and other carbonaceous minerals–appears to coat equator-facing slopes and crater floors. The distribution of this material and variations in the color of the bright material across the trailing hemisphere will be crucial clues to understanding the origin of Iapetus’ peculiar bright-dark dual personality.

There are several theories to explain the planet’s strange ying-yang two-tone coloration. One suggests it is material thrown off by other Saturn moons that Iapetus sweeps up. Other theories suggest the planet’s orbit itself causes the two hemispheres to have different temperatures, allowing material to sublimate off the dark side and to the bright side.

No theory is presently accepted. Nor does any explain the data fully.

Tomorrow I’ll post a most intriguing close-up of Iapetus taken by Cassini during that 2007 fly-by.

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Pluto’s cratered glacial terrain

12:56 pm

Panorama of Pluto's eastern limb
Click for full resolution. For original images go here, here, here, and here.

Pluto in true color
Click for original image.

Cool image time! The panorama above, created from four New Horizons’ images that were cropped and enhanced to post here, was taken by New Horizons on July 14, 2015 (here, here, here, and here), about 30 minutes before its closest approach of 7,800 miles above Pluto.

I have searched the New Horizons’ press release archive, and as far as I can tell, this sequence of images and the terrain it shows was never highlighted publicly by the science team. For that reason, I am not sure exactly where to place it on the global true-color image of Pluto to the right, released by the science team shortly after that fly-by. I suspect the panorama covers a strip on the eastern limb of the globe, in the darker crater region to the east of Pluto’s giant frozen nitrogen sea. It is also possible this is actually covering the north pole regions, with the raw images as released oriented with north to the right.

Other than these guesses I cannot tell. If anyone has better information please provide it in the comments.

What the panorama does show us is cracked and pitted terrain, thought to be mostly made up of frozen ice mixed with dust and debris with some nitrogen and other materials thrown in. Though in many ways it resembles the Moon, that similarity is only very superficial. For example, the polygon shapes near the picture’s center suggest ice floes or glaciers, though there is no underground liquid ocean on which they could float.

This is a very alien world. And it is likely even more alien than the few pictures obtained during that New Horizons’ fly-by have suggested. After all, we only saw in high resolution one hemisphere. Who knows what’s really on the planet’s other side?

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Charon’s surface, completely unlike Pluto

1:09 pm

Panorama of part of Charon's surface
Click for full resolution. For original images go here, here, and here.

Charon

Cool image time! The panorama above, created from three images taken by New Horizons as it began its July 14, 2015 fly-by of the Pluto-Charon double planet system (found here, here, and here), show in close-up one specific swath of Charon cutting across its equatorial regions.

The true color global image of Charon to the right shows the approximate area covered by the panorama above. For scale, Charon has a diameter of about 750 miles, about half that of Pluto. For clarity I have rotated the panorama so that it more closely aligns with the rectangle of global image.

One of the most remarkable discoveries made during New Horizons’ fly-by was how completely different Pluto and Charon appeared, despite their likely formation together at the same time and in the same location of the early solar system. While Pluto had frozen nitrogen seas and water ice mountains floating at the shores, Charon more resembled Mercury, cratered with many large ridges and canyons criss-crossing its service. Both planets appear to be icy, but somehow Charon appears to lack the large differentiated variety of materials seen on Pluto.

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Mars’ fast moving gigantic lava floods

2:23 pm

A Martian crater broken by flowing lava
Click for original image.

Cool image time! The picture to the right, rotated, cropped, and reduced to post here, was taken on December 12, 2025 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

The science team labels this a “crater interrupted by flow.” And what a flow! This unnamed 1.4-mile wide crater was not only filled and partly buried by the flow, that flow was so strong it cut through the crater’s rim at two points, refusing to let that rim block it in any way.

The flow in this case is lava, coming down from the Tharsis Bulge where four of Mars’ biggest volcanoes arose. And that flow was quite vast, as the nearest of those volcanoes, Arsia Mons, is almost 800 miles away. Because of Mars’ relative light gravity, about 39% that of Earth’s, lava on Mars can flow across large distances in a very short time. It might have only taken a few weeks for that flow to cover that 800 miles.
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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.
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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.
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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.
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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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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.
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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.
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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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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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