Jupiter’s Great Red Spot continues to shrink, possibly to its smallest size ever measured

Jupiter, as seen by Hubble in 2020
A 2020 Hubble picture of Jupiter.
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Long term data from numerous observatories shows that the Great Red Spot on Jupiter, the largest and longest lasting storm in the solar system, has been continuously shrinking for decades, and appears approaching this year its smallest size ever measured.

Despite so many factors working to keep it “alive” the Spot may be in need of life support. It’s been shrinking for decades. In 2012 the rate of shrinkage abruptly accelerated, something many amateur observers have commented on since that time. Several years later, while still shrinking in diameter, it expanded in latitude becoming more circular. Now it’s narrowed again and continues to diminish in both axes. This observing season I’ve been struck by the Spot’s unusually small size. That, along with its pale pink color and turbulent environment, have made it less obvious than ever.

…Using the WinJUPOS program and one of his recent high-resolution images, Peach measured the Great Red Spot’s diameter on November 6, 2023, at 12,500 kilometers or about 7,770 miles across. If confirmed it would make this season’s GRS not only smaller than the Earth (12,756 kilometers or 7,926 miles across) but the smallest size in observational history. A British Astronomical Association Jupiter section bulletin on October 30th described it as “the smallest it has ever been.” That’s a far cry from the late 1800s when the Spot ballooned to 41,000 kilometers (25,500 miles) — big enough to swallow three Earths with room to spare. Now it can barely contain one!

No one knows if this shrinkage is merely a normal long term fluctuation, or a sign that this many-centuries-old storm is finally dissippating. When it comes to the solar system’s gas giants, their size and long orbits make any firm conclusion difficult in only a few centuries of observation. To understand them properly will likely require thousands of years of observations, covering many orbits and seasons.

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Lava/ice eruptions on Mars

Lava/ice eruptions on Mars
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on August 1, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). Labeled by the science team as showing “possible lava-ice interaction,” the photo features some pimply-looking mounds that, though round like craters, sit above the surrounding landscape like small volcanoes.

That these are likely not ancient pedestal impact craters that now sit higher because their material is packed and can resist erosion is illustrated by the bridge-like mound in the lower right. This mound was likely once solid, but its north and south sections have disappeared, either by erosion or sublimation. If formed by an impact the mound would have had a depression in its top center, and would have only eroded outside the rim.
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Intuitive Machines will attempt to launch 3 lunar landing missions in 2024

South Pole of Moon with landing sites

According to the company’s CEO, Intuitive Machines is pushing to fly two more Nova-C lunar landing missions next year after its first is launched by SpaceX on January 12th and hopefully lands successfully near the Moon’s south pole on January 19th.

Intuitive Machines is working on two more Nova-C landers for its IM-2 and IM-3 missions, also carrying NASA CLPS payloads. The company has not announced launch dates for those missions, but Altemus said he hoped both could take place by the end of 2024.

“We are planning three missions in 2024,” he said, which will depend in part on NASA’s requirements as well as orbital dynamics. Landings at the south polar region of the moon, the target for IM-2, are linked to “seasons” where lighting conditions are optimal for lander operations. IM-3, he said, would happen “a few months” after IM-2.

Though Nova-C will launch after Astrobotic’s Peregrine lander (launching on ULA’s Vulcan rocket), it will get to the Moon quickly, and will attempt its landing first. If successfully it will therefore be the first private payload to do so.

The company’s ambitions for 2024 are laudable, but depend so entirely on everything going perfectly it will not be surprising if they do not pan out. Nor will it reflect badly on the company if just one mission flies in 2024. Landing a robot on another world is hard. For private companies to do it is harder.

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The caldera wall of a Martian giant volcano

The caldera wall of Pavonis Mons
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Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on June 8, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the top half of the northwestern interior wall of the central caldera of Pavonis Mons, the center volcano in the string of three giant volcanos found in Mars’ equatorial regions.

The elevation change from the top to the bottom of this picture is about 7,000 feet, though this covers only half the distance down to the floor of the caldera. The picture was taken as part of a survey of this caldera wall.

Volcanic activity here is thought to have ended more than a billion years ago. Thus we are looking at relatively old terrain that has had many eons to be reshaped since the last eruption.
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The strange craters in the high northern latitudes of Mars

The strange craters in the Martian northern lowlands
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Cool image time! The picture to the right, rotated, cropped, reduced, and enhanced to post here, was taken on August 22, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I have also inserted data from a July 28, 2008 context camera image into the blank strip that now exists in the center of high resolution camera images due to the failure of one sensor.

This photo is what the camera team calls a terrain sample, and was probably taken not as part of any specific request 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 find locations that either have not been observed in much detail previously or have interesting features. In this case the team accomplished both. The interesting features are the two pedestal craters, both surrounded by splash aprons. Neither has been observed in high resolution previously, and the context camera has only taken two pictures of this location in total.
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Strange meandering ridge amidst Martian glaciers

Overview map

Strange meandering ridge in glacier country

Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken on June 21, 2023 by the high resolution camera on Mars Reconnaissence Orbiter (MRO). Its focus is the meandering ridge in the center of the picture, which the scientists intentially describe vaguely as a “ridged flow-like feature”.

The elevation difference between the high and low points within the picture is about 500 feet, though most of that slope occurs in the lighter terrain on the right. The darker area where the ridge is located has no clear elevation trend, though there are hints of depressions and rises within it.

The yellow dot on the overview map above marks this location, deep within the chaos terrain dubbed Deuteronilus Mensae, on the western end of the 2,000 long northern mid-latitude strip I dub glacier country, because practially every image from there shows glacial features.

To underline this fact, the red and white dots mark previous cool images from 2020 and 2021, with the first showing an eroded glacier and the second glacial ice sheets.

The mesa to the east of this picture rises more than 6,000 feet to its peak, as indicated by the black dot. This is also the highest point for this entire grouping of mesas. All are surrounded by a single large apron of material, likely a mixture of alluvial fill and ice.

What however caused the narrow ridge in the picture above? Is it ice or bedrock? If ice why is it so different than the glacial material that seems to surround it? If bedrock, it suggests it is instead an ancient inverted channel created when that ridge was a canyon through which ice or water flowed, compacting the canyon floor. When the terrain around it eroded away it was more resistent and became a ridge instead.

I have no answer. The colors suggest the ridge is rock, not ice, but that is not conclusive.

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The grand Valles Marineris of Mars

The grand canyon of Mars
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Time for another cool image of the grand canyon of Mars, Valles Marineris. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on May 24, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a small section of the floor of this gigantic canyon, where orbital data has detected light-toned materials. From the caption:

Many of the Valles Marineris canyons, called chasmata, have kilometer-high, light-toned layered mounds made up of sulfate materials. Ius Chasma, near the western end of Valles Marineris, is an exception.

The light-toned deposits here are thinner and occur along both the floor and walls, as we see in this HiRISE image. Additionally, the sulfates are mixed with other minerals like clays and hydrated silica. Scientists are trying to use the combination of mineralogy, morphology, and stratigraphy to understand how the deposits formed in Ius Chasma and why they differ from those found elsewhere in Valles Marineris.

The picture however gives no sense of the monumental terrain that surrounds it.
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Martian lava that buried a crater

Martian lava flow through crater
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Cool image time! The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on June 24, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows a lava flow that cut through an older 2-mile-wide crater, mostly burying it as it burst through the crater’s southwest and northeast rims. From the caption:

A lava channel extends from the feature and continues 60 kilometers to the northeast, growing deeper along its path. The circular formation is likely an eroded impact crater whose walls have been breached by the lava as it surrounded the rim and then infilled the crater. Alternatively, it could represent the location of a volcanic vent that sourced some of the lavas that formed the channel.

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Galaxies within galaxies within galaxies

Galaxies within galaxies
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Time another cool galaxy image! The picture to the right, cropped, reduced, sharpened, and annotated to post here, was taken by the Hubble Space Telescope as part of a survey project of galaxies where past supernovae had occurred. From the caption:

The location of this faded supernova was observed as part of a study of multiple hydrogen-rich supernovae, also known as type II supernovae, in order to better understand the environments in which certain types of supernovae take place.

Though the picture’s resolution was reduced to post here, I have also included insets at the full released resolution of three of background galaxies, one of which (on the uppermost right) appears to have a second smaller galaxy either associated with it or is another background galaxy even farther away. Such background galaxies are always seen Hubble images, which starkly tell us that the universe is far vaster than we can imaging, with more stars than we can conceive.

The galaxy featured here is interesting in its own right. Though it appears to be a spiral galaxy, its arms are very indistinct, suggesting that is sits between that of an elliptical galaxy (no arms, just a cloud of stars) and a spiral (with well-defined arms).

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Ingenuity completes very short 65th flight

Overview map
Click for interactive map.

Ingenuity yesterday completed a very short 48 second flight that shifted its position only slightly to the west, by about 23 feet. The distance, time, and highest elevation (33 feet) matched the flight plan exactly.

The green dot on the overview map above indicates its present position, with the blue dot marking Perseverance’s location. This particular flight was so short that it actually fits entirely within that green dot. Furthermore, the helicopter’s next flight, scheduled for today as well, is intended to also only reposition the helicopter, but even less so, moving only two feet or so sideways while rising only ten feet.

It appears the engineering team is preparing the helicopter for the upcoming solar conjunction, when the Sun will be between the Earth and Mars and no communications will be possible for several weeks. Such conjunctions occur about every two years, with this one beginning on November 6th and lasting until November 29th. Getting the helicopter in the right spot during that down time will increase the chances for regaining communications afterward. Since Perseverance acts as a relay station, Ingenuity must get placed in a spot where there is a direct line of communications, blocked by no objects or intevening rise in land.

Note that all the Martian rovers and orbiters are preparing for conjunction right now.

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Mars geology that only makes sense by digging deeper

Not-so baffling Martian geology
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Today’s cool image is a perfect example of why nothing in science research should ever be taken at face value, without digging a bit deeper. The picture to the right, rotated, cropped, reduced, and sharpened to post here, was taken on October 5, 2023 by the high resolution camera on Mars Reconnaissance Orbiter (MRO).

First an important technical point. Though the electronics unit for one of the camera’s color filters is still not working — causing a blank strip down the center of all black & white images, the camera team has gotten around this problem by inserting in that strip other color filter data, thus creating a complete image as you see to the right. This work-around means that MRO’s capabilities, though showing signs of age, will continue almost as good as before.

As for the image itself, when I first looked at it, I was baffled by the striking contrast between the mottled and rough ground in the lower left, and the almost featureless and smooth terrain everywhere else. Why this sudden transition? What could cause it? That inexplicable contrast demanded I post it as a cool image.
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Lucy discovers second small asteroid orbiting Dinkinesh

Dinkinesh as seen by Lucy

During its November 1, 2023 fly-by of the asteroid Dinkinesh the asteroid probe Lucy surprisingly discovered that the asteroid was actually a binary, with a second smaller asteroid orbiting it.

The picture to the right, cropped, reduced, and sharpened to post here, was taken by Lucy’s camera within a minute of the probe’s closest approach of 270 miles. The second asteroid is partly blocked by Dinkinesh.

In the weeks prior to the spacecraft’s encounter with Dinkinesh, the Lucy team had wondered if Dinkinesh might be a binary system, given how Lucy’s instruments were seeing the asteroid’s brightness changing with time. The first images from the encounter removed all doubt. Dinkinesh is a close binary. From a preliminary analysis of the first available images, the team estimates that the larger body is approximately 0.5 miles (790 m) at its widest, while the smaller is about 0.15 miles (220 m) in size.

The nature of both asteroids appears to lie between a rubble pile (like Bennu) or a solid smooth rock (like Eros), suggesting we are now beginning to see aspects of the overall evolution of asteroids over time.

So far only a few images from this fly-by have been released. It will take a week for the rest of the data from the fly-by to beamed back to Earth. However, these images prove that the prime purpose of this fly-by was successful, proving that Lucy is operating as planned, able to point, manuever, and obtain its data during such a fly-by. When it arrives in the Trojan asteroids in 2027 it will be able to do its prime mission.

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