Tag: science

Sunspot update: Is this sunspot maximum over, or will it become another doubled peaked maximum?

12:43 pm

Well, after almost fifteen years it had to happen at last. In preparing to do my monthly sunspot update today, which I had done every month since I started Behind the Black in 2010, I discovered that I had completely forgotten to do the update in December. Sorry about that.

No matter, the changes from month-to-month are not often significant, and fortunately that turned out to be the case in November and December of 2024. Since my last update at the beginning of November 2024, sunspot activity on the Earth-facing hemisphere of the Sun has been relatively stable, based on NOAA’s monthly graph tracking that activity. In November the activity dropped slightly, only to recover a small amount in December.
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A strange dune in the high southern latitudes of Mars

2:56 pm

A strange dune in the high latitudes of Mars
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 24, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have also rotated the image so that north is to the top.

The scientists label this a “dune with seasonally persistent light-toned features.” As the location is in the high southern latitudes, only about 800 miles from the south pole, light-toned features should vary by seasons, as such features usually signal the coming and going of frost, whether it be water ice or dry ice. In this case however the light tones remain from season to season, which suggests the lighter colors are intrinsic to the ground and possibly signal some interesting geology or mineralogy.

The color strip down the center of the dune is an effort to decipher this question. According to the explanation about the colors [pdf] provided by the science team, the orange and light green probably indicates fine dust, while the greenish area along the ridge’s rim as well as its eastern slope suggests frost. Thus, based on the superficial information available to the public, the colors tell us little.
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A fading supernova 650 million light years away

10:18 am

A fading supernova 650 million light years away
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope in March 2024, and shows the fading blue light of a supernova that was first discovered by another survey telescope six weeks earlier. The galaxy, dubbed LEDA 22057, is estimated to be about 650 million light years away.

The supernova is the bright spot in the galaxy’s southeast quadrant near the edge of the galaxy’s bright body. From today’s caption release:

SN 2024PI is classified as a Type Ia supernova. This type of supernova requires a remarkable object called a white dwarf, the crystallised core of a star with a mass less than about eight times the mass of the Sun. When a star of this size uses up the supply of hydrogen in its core, it balloons into a red giant, becoming cool, puffy and luminous. Over time, pulsations and stellar winds cause the star to shed its outer layers, leaving behind a white dwarf and a colourful planetary nebula. White dwarfs can have surface temperatures higher than 100,000 degrees and are extremely dense, packing roughly the mass of the Sun into a sphere the size of Earth.

While nearly all of the stars in the Milky Way will one day evolve into white dwarfs — this is the fate that awaits the Sun some five billion years in the future — not all of them will explode as Type Ia supernovae. For that to happen, the white dwarf must be a member of a binary star system. When a white dwarf syphons material from a stellar partner, the white dwarf can become too massive to support itself. The resulting burst of runaway nuclear fusion destroys the white dwarf in a supernova explosion that can be seen many galaxies away.

The rate in which this supernova fades will help astronomers untangle the processes that cause these gigantic explosions. Though the caption makes it sound as if we know how this happens, we really don’t. There are a lot of assumptions and guesses involved in the description above, based on the limited knowledge astronomers have gathered over the past few centuries looking at many supernovae many millions of light years away.

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Why this place in Valles Marineris is NOT a good place to establish trails and inns

11:57 am

Overview map

North rim and the top of the trail
Click for original image.

In my cool image yesterday I highlighted a location along the north rim of the gigantic Valles Marineris canyon on Mars that appeared a great place to establish a hiking trail. The trail would take hikers down from the rim to the floor of the canyon, a distance of more than 20 miles with an elevation loss of more than 31,000 feet, more than the height of Mount Everest. The image to the right shows the top of that trail, at the rim. The white dot on the overview map above shows its location in Valles Marineris.

Because of the trail’s length I also suggested that future colonists would likely set up inns along the way, so that hikers would have places to stay as they worked their way downhill day-by-day.

There is however one major reason not to build at this particular location, and it involves the most significant geological detail I noticed in the picture to the right. Note the arrows in both this image as well as the inset above. In the picture they mark a sudden drop paralleling the rim. In the inset they also show a series of parallel cracks further north.

The cliff and the cracks suggest that the entire cliff of this part of the north rim has subsided, and is in fact beginning to separate from the plateau, and will soon (in geological terms) collapse into a spectacular avalanche. If you look at the cliff face in the inset you can see two extended outflow piles that apparently came from smaller earlier such collapses.

Could this entire cliff face, the size of Mount Everest, actually separate and crash into the canyon? If you have doubts, then take a look at the image below.
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Parker probe phones home, signalling it has successfully survived its record-breaking closest approach to the Sun

9:42 am

Parker flight plan
The flight plan for Parker. Click for original.

NASA today reported that it has received a signal from the Parker Solar Probe, indicating all of its systems are in good health following its record-breaking closest approach to the Sun on December 24, 2024.

The mission operations team at the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland received the signal just before midnight EST, on the night of Dec. 26. The team was out of contact with the spacecraft during closest approach, which occurred on Dec. 24, with Parker Solar Probe zipping just 3.8 million miles from the solar surface while moving about 430,000 miles per hour.

Not only was this the closest any human-built object has gotten to the Sun, it was the fastest any human-built object has ever traveled.

This close fly-by was Parker’s 22nd of the Sun since launch. In its nominal mission it plans to do two more close approaches as shown in the graphic to the right, both of which will be comparable to the record just set.

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Just one of many potential hiking trails down into Valles Marineris

12:10 pm

Overview map

Just one of many potential trails into Valles Marineris
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 15, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The white dot on the overview map above shows the location, on the northern interior wall of the vast Valles Marineris canyon on Mars.

As my readers know, I tend to look at the spectacular Martian photos coming back from the orbiters and rovers as much from a tourist perspective as that of a scientist. Thus, for this picture, my first thought was to consider the possibility of a trail weaving its way down the nose of that ridgeline and into the canyon. In the Grand Canyon such ridgelines often provide a route down where walking is possible the entire way, with no need for climbing or ropes.

To illustrate my thought, I have indicated the potential trail with the white line. All told this trail covers about 7.2 miles, and drops 12,500 feet. Such a drop is very steep for trails on Earth, with an average grade of 14 degrees and about three times the grade considered reasonable. On Mars, however, with its one-third gravity, I think a grade this steep would be reasonable, though certainly daunting mentally. You would not only be descending on a very steep slope, you would be doing so on the peak of this ridge, with drops of one to two thousand feet on either side.

Amazingly, the inset on the overview map shows that this trail gets you less than halfway to the bottom. All told, the drop from canyon rim to floor at this location is about 31,000 feet over 20 miles, a drop that is greater than climbing down from the top of Mount Everest. If I was to install a trail here I’d also build an inn or two along the way as rest stops for hikers.

What the trail would do is get you to the bottom of this particular ridgeline. From here the trail would have to drop off into the western hollow and from then on descend on top of its alluvial fill. The slope would be as steep, but it would be possible to alleviate that by putting in switchbacks. This would lower the grade, but increase the distance traveled significantly.

Geologically, this image shows to my eye one particular feature that is quite significant, at the rim. I will discuss this tomorrow, in my next cool image.

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A Martian river of sand

11:33 am

Overview map

A Martian river of sand

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 26, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). The red dot in the overview map above marks the location, within the western reaches of the vast Martian canyon dubbed Valles Marineris.

The picture looks at the flow of dust and sand going down the canyon’s southern rim, with particular focus on the central canyon in the picture’s center. The photo was taken as part of a long-term project, begun in 2020 to monitor this river of sand to see if any changes occur over time. Clearly the sand is flowing downhill, almost like a river, with the dunes almost resembling waves. The geological issue is to determine how fast. Based on the resolution available to me, it is impossible to tell it there have been any changes in the past four years, but the full MRO dataset might reveal more information.

To get an idea of scale, the elevation loss from the top to the bottom in this picture is about 6,000 feet. While this seems like a substantial amount, it pales when placed in the context of Valles Marineris. For example, the elevation loss for the canyon’s northern wall is about 25,400 feet, making that wall exceed in height most of the mountains in the Himalayas. And that wall extends for more than 1,500 miles.

Valles Marineris’ southern wall is more complex. It rises about 18,000 feet from the floor of the canyon to the top of the peak on which this slope sits, but then drops 6,700 feet into a parallel side canyon. From there the rise to the southern rim is about 11,000 feet. All told the southern rim sits about 23,000 feet above the canyon floor, once again a drop that would exceed most mountains on Earth.

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Using Hubble to monitor a fading supernova

9:38 am

Barred spiral
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of a monitoring program of the fading supernova that occurred in this galaxy in 2014, 60 million light years away. I have added a white dot to indicate the approximate location [pdf] of that supernova, as it is now too dim to see clearly in the original image. From the caption:

Researchers have determined that SN 2014cx was a Type IIP supernova. The “Type II” classification means that the exploding star was a supergiant at least eight times as massive as the Sun. The “P” stands for plateau, meaning that after the light from the supernova began to fade, the level reached a plateau, remaining at the same brightness for several weeks or months before fading further. This type of supernova occurs when a massive star can no longer produce enough energy in its core to stave off the crushing pressure of gravity. SN 2014cx’s progenitor star is estimated to have been ten times more massive than the Sun and hundreds of times as wide. Though it has long since dimmed from its initial brilliance, researchers are still keeping tabs on this exploded star, not least through the Hubble observing programme which produced this image.

The blue regions in the galaxy’s periphery suggest younger stars, while the gold color in the interior suggests an older population.

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Perseverance takes its first good look west at its future journey

12:32 pm

Peservance looks west
Click for original image.

Cool image time! The picture to the right, reduced and enhanced to post here, was taken today by the left navigation camera on the Mars rover Perseverance. Though I am not 100% certain, I think this picture looks almost due west, and is aimed not only at the rover’s near term target, Witch Hazel Hill, but the rover’s long term and very important goal, the Nils Fossae ridge and canyon that appears to be crack formed during the impact that created giant 745-mile-wide Isidis Basin. Jezero Crater sits on the western rim of that impact basin.

The rover team expects to reach Witch Hazel Hill within days. To get there quickly the team has moved the rover more than a thousand feet west and dropped down from the rim about 170 feet in just the past ten days.
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Land of dust devils

2:17 pm

Land of dust devils
Click for original image.

Today’s cool image to the right demonstrates that the atmosphere and climate of Mars is truly different in different places. The picture, rotated, cropped, reduced, and sharpened to post here, was taken on July 22, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled simply as a “terrain sample”, it was likely taken not as part of any specific research project but to fill a gap in the camera’s schedule in order to maintain its proper temperature.

I post it today almost to illustrate the difference between this location and the spot where the lander Insight landed on Mars. Earlier this week the MRO camera team released a short movie created by images of the lander taken over six years, showing how the dust around it had changed over time. I noted further how those images showed a very small number of dust devil tracks, which explained why no dust devil every crossed over the lander’s solar panels to clean them of dust.

For the picture on the right, however, there are a lot of dust devil tracks, so many near the bottom that they almost completely darken the ground.
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Curiosity looks down and across Gale Crater

10:43 am

Curiosity looks down across Gale Crater
Click for original image.

Cool image time! The picture to the right, cropped, reduced, and enhanced to post here, was part of a panorama created by 24 photos taken by the right navigation camera on the Mars rover Curiosity on December 16, 2024.

The view looks west at the foothills that fill the lower slopes of Mount Sharp. In the far distance, about 20 to 30 miles away, can be seen the western rim of Gale Crater, obscured by the dust in the Martian atmosphere.

Curiosity is presently contouring west along the mountain slope. As it goes it will pass a series of canyons coming down the mountainside. The goal is to eventually reach the canyon the science team has chosen to take for climbing that mountain.

Note the rocky ground. One of the surprises found as Curiosity left the crater floor and started climbing Mount Sharp about four years ago is the rockiness of the terrain. Unlike Earth, Mars’s atmosphere and environment does not have the activity to smooth out this landscape. While science data suggests flowing water was once present here, it wasn’t here long enough to smooth things out. And the atmosphere is just too thin.
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Astronomers discover 1st binary star system orbiting Milky Way’s central supermassive black hole

9:40 am

The stars orbiting Sag A*
The stars orbiting Sag A*. Click for original image.

Using infrared spectroscopic data gathered from 2005 to 2019 by the Very Large Telescope in Chile, astronomers have identified the first known binary star system to orbit Sagittarius A* (pronounced “A-star”), the Milky Way’s central supermassive black hole.

You can read their science paper here [pdf]. The white dot at the center of the map to the right marks the location of Sagittarius A*, while the red dot marks the present location of the binary star, dubbed D9. The other objects are the stars previously identified orbiting the central black hole, all of which are now believed to be single stars. The binary D9 has an estimated orbit around Sagittarius A* of 432 years and is thought to be less than three million years old. The two stars have approximate masses of 3.86 and 2.8 solar masses, with the smaller orbiting the larger every 372 days.

There is a lot of uncertainty in these numbers, but the data identifying the binary is quite firm. This discovery, as well as the many other stars now known to orbit Sagittarius A*, show that star formation so close to a supermassive black hole is not only possible, it is common, something astronomers a decade ago thought impossible.

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New computer simulations suggest Saturn’s rings are not young but formed at the same time as the solar system

9:12 am

A bright spot in Saturn's rings
Click for original source.

The uncertainty of science: Scientists doing computer simulations now posit that Saturn’s rings are not young, between 100 to 400 million years old as has been believed for the last few decades, but formed instead when Saturn formed, 4.6 billion years ago.

You can read their paper here [pdf].

The young age had been based on data from the Cassini orbiter, which showed the ring particles to be very bright and clean. If old those particles would have been darker as they accumulated dust over time on their surface. The new computer simulations suggest a process whereby those particles get “cleaned,” thus making it possible for the rings to be very old, possibly as old as Saturn itself.

Must I point out the uncertainties? The paper itself admits in its abstract “uncertainties in our models that assume no porosity, strength, or ring particle granularity.” Seems these assumptions make the conclusions very uncertain indeed.

Then again, the previous young estimates of the age of the rings had many similar assumptions and uncertainties. Essentially, we don’t have enough information to make any definitive determinations.

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A galactic eye in heaven

12:30 pm

A galactic eye in space
Click for original image.

Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope as part of a project to study the star formation processes over time in this galaxy, located about 76 million light years away.

A prominent bar of stars stretches across the centre of this galaxy, and spiral arms emerge from each end of the bar. Because NGC 2566 appears tilted from our perspective, its disc takes on an almond shape, giving the galaxy the appearance of a cosmic eye.

As NGC 2566 gazes at us, astronomers gaze right back, using Hubble to survey the galaxy’s star clusters and star-forming regions. The Hubble data are especially valuable for studying stars that are just a few million years old; these stars are bright at the ultraviolet and visible wavelengths to which Hubble is sensitive. Using these data, researchers will measure the ages of NGC 2566’s stars, helping to piece together the timeline of the galaxy’s star formation and the exchange of gas between star-forming clouds and stars themselves.

To get the full picture, astronomers have also obtained infrared data from the Webb Space Telescope and millimeter/submillimeter radio wavelength data from the ALMA telescope.

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The Insight lander on Mars as seen from orbit over six years

12:07 pm

Insight as seen by MRO over six years
Click for movie.

Using photos taken by Mars Reconnaissance Orbiter (MRO) from 2018 to 2024, researchers have compiled a short movie showing how the dust around the Mars lander Insight changed over time.

This video shows images taken by HiRISE between Dec. 11, 2018, just a couple weeks after InSight landed on Mars, and Oct. 23, 2024. In the images, InSight often appears as a bright, blue dot due to its reflection of sunlight. A dark halo was scorched into the ground by the spacecraft’s retrorocket thrusters; this halo fades away over time. Dark stripes that can be seen on the surface are tracks left by passing dust devils. [emphasis mine]

You can see the movie here. The image to the right was the first picture taken by MRO only three weeks after landing.

Insight eventually shut down because this dust accumulated on its solar panels, and the lander never was blessed with having a dust devil cross over it to blow that dust away. This video illustrates why. Out of the seven images making up the short movie, only three show dust devil tracks, and in each case only a few tracks are seen. No other tracks are detected.

In other words, over six years this region simply did not get a lot of dust devils. The odds of one crossing over InSight was thus quite low. Ironically, the image to the right shows that a dust devil crossed very close to the lander about the time it landed in 2018, probably just beforehand since the dark scorch created by the lander’s thrusters cover the track. No dust devil ever got that close again.

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Juno spots changes on Io’s surface in just a two-month span

10:57 am

Before and after images by Juno of volcanic ring on Io
Click for original image.

New photos taken just two months apart by Juno of a region dubbed Nusk Patera on the Jupiter moon Io showed the appearance of a distinct ring that had hardly been there before.

The pictures, taken during two recent fly-bys of the moon, are above, and show the change. From the caption:

A red ring formed around Nusku Patera in the two months between the spacecraft’s 58th flyby on Feb. 3, 2024, and its 60th on April 9, 2024. The ring obscures some nearby features like Creidne Patera. This ring, 683 miles (1,100 kilometers) wide is likely from a Pele-type plume rich in sulfur. Similar transient red rings were observed by NASA’s Galileo mission around Grian Patera and Surt and were associated with intense but short-lived thermal “outburst” eruptions.

In other words, sulfur from eruption from the central vent/caldera was flung into the sky enough that when it eventually settled back down it landed in a ring about 340 miles away from the center.

Other data from Juno, also released this week here and here, detected fresh lava flows at another volcanic region of Io dubbed, Zal Patera.

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Perseverance reaches top of Jezero Crater rim

1:41 pm

The view west out of Jezero Crater
Click for high resolution panorama. For original images, go here and here.

Overview map
Click for interactive map.

After spending more than three and a half years exploring the floor of Jezero Crater, the rover Perseverance has finally reached the top of the crater’s western rim, and is about to begin exploring the mountainous and potentially rich mining region to the west.

The panorama above, created from two pictures taken by Perseverance’s right navigation camera on December 11, 2024 (here and here), has been cropped, reduced, enhanced, and annotated to post here. It looks west into that mountainous region, with the yellow lines on the overview map to the right indicating the approximate view. The blue dot on that map marks Perseverance’s present position, on top of Lookout Hill, the name the rover team has given to that spot on the rim.

The low resolution of the region beyond the grey strip is unexplained. For some reason the rover team has not yet updated the interactive map showing Perseverance’s travels with the many high resolution pictures that Mars Reconnaissance Orbiter (MRO) has taken of this region, in anticipation of Perseverance’s travels there. I expect however this will change shortly.

Witch Hazel Hill is the first target beyond the rim, where there is an outcrop 330-feet-high with many layers. The rover will then head downhill and south to check out a spot that the scientists believe might show features existing from before Jezero Crater was formed. The rover will then head back up to the rim further south to look at an outcrop of blocks that might actually be ejecta from another much larger Martian impact.

These blocks may represent ancient bedrock broken up during the Isidis impact, a planet-altering event that likely excavated deep into the Martian crust as it created an impact basin some 745 miles (1,200 kilometers) wide, 3.9 billion years in the past.

Jezero sits on the northwestern rim of Isidis.

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Curiosity begins to round the corner out of Gediz Vallis

11:37 am

Curiosity looks ahead
Click for original image.

According to an update yesterday from the rover team, the Mars rover Curiosity has finally begun to round the corner of the northern nose of the long ridge dubbed Texoli that forms the western wall of Gediz Vallis, the slot canyon that the rover has been exploring since August 2022.

The picture to the right, reduced, sharpened, and annotated to post here, was taken on December 10, 2024 and shows the view looking west. The red dotted line indicates the planned route. As the rocky ground indicates, travel forward in the near term will be interesting. As noted in the update:

While we want to head southwest, we had to divert a bit to the north (right of the image shown) to avoid some big blocks and high tilt. The path is very constrained in order to avoid driving over some smaller pointy rocks, scraping wheels along the sides of blocks, or steering into the side of blocks that might cause the steering to fail. And we also needed to worry about our end-of-drive heading to be sure the antenna will be clear to talk to Earth for the next plan. We ended up relying on the onboard behavior to help us optimize everything by implementing a really interesting and curvy 24-meter path (about 79 feet).

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Land of knobs

12:53 pm

Land of knobs
Click for original image.

Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on July 17, 2024 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled merely as a “terrain sample,” it was likely taken not as part of any specific research project, but to fill a gap in the camera’s schedule in order to maintain its proper temperature.

When the camera team does this, they try to pick interesting targets. In this case, they targeted this 400-foot-high pointy-topped hill. The smoothness of its slopes suggest this hill is made up largely of packed dust, possibly a hardened former dune. This hypothesis seems strengthened by the erosion on the eastern slopes, which appears to be areas where that packed sand has worn or blow away.

Think of sandstone in the American southwest. It is made of sand that has hardened into rock, but wind and water and friction can easily break it back into dust particles, resulting often in the spectacular and weird geological shapes that make the southwest so enticing.

But is this sand?
» Read more

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Io’s volcanoes get their lava from separate magma chambers, not a global underground ocean of magma

11:11 am

Io's interior as presently theorized
Click for original animation.

Using data collected from Juno’s multiple fly-bys of the Jupiter moon Io, scientists now hypothesize that the moon does not have a global underground ocean of magma, feeding its many volcanoes, but that instead each volcano is fed its lava from a separate magma chamber.

The graphic to the right illustrates the present conclusion. You can read the paper here [pdf]. From the press release:

The Juno team compared Doppler data from their two flybys with observations from the agency’s previous missions to the Jovian system and from ground telescopes. They found tidal deformation consistent with Io not having a shallow global magma ocean.

“Juno’s discovery that tidal forces do not always create global magma oceans does more than prompt us to rethink what we know about Io’s interior,” said lead author Ryan Park, a Juno co-investigator and supervisor of the Solar System Dynamics Group at JPL. “It has implications for our understanding of other moons, such as Enceladus and Europa, and even exoplanets and super-Earths. Our new findings provide an opportunity to rethink what we know about planetary formation and evolution.” [emphasis mine]

The highlighted words indicate the significance of this data. It possibly suggests that the underground oceans of water that have been theorized for these other moons — where life could possibly exist — might be mistaken. Instead, they might have smaller pockets of water, similar to Io’s many magma chambers.

Everything here however is uncertain, including these new conclusions about Io. We just don’t have enough data from any of these moons to make any definitive conclusions.

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