Tag: science

Giant impact covered almost half of Gandymede’s surface

9:31 am

Artist's illustration of Ganydmede
Click for full illustration.

The uncertainty of science: Computer modeling and a review of images taken by Voyager 1 and 2 and the Galileo orbiter of Jupiter’s moon Ganymede now suggest the existence of a giant impact so large that it covers almost half the moon’s surface.

The artist’s illustration of Ganymede on the right, based on our presently incomplete set of global images, shows this impact area as the circular dark region.

Many furrows, or trough formations, have been observed on the surface of Ganymede, one of the Jovian moons. This research group comprehensively reanalyzed image data of Ganymede obtained by NASA’s Voyager 1, Voyager 2, and Galileo spacecrafts. The results revealed that almost all of these furrows appear to be arranged in concentric rings centered around a single point, indicating that this global multiring structure may be the remains of a giant crater. The radial extent of the multiring structures measured along Ganymede’s surface is 7800 km. For comparison, the mean circumference of Ganymede is only 16,530 km. If correct, this is the largest crater yet identified in the Solar System. The previous record holder with a 1900 km radius is on Calisto, another Jovian moon.

The conclusion reached here is very uncertain, since we really do not have a high resolution global map of Ganymede. All three spacecraft were only able to send back a scattering of high resolution images. The global map is based on Earth observations and images from the Hubble Space Telescope.

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Betelgeuse dimming caused by outburst

9:08 am

The uncertainty of science: According to new data from the Hubble Space Telescope, astronomers are now proposing that the dimming seen earlier this year in the red giant Betelgeuse was caused not by a known variation cycle or by a large starspot moving across its surface, but by an large outburst of material, thrown out from the star.

Ultraviolet observations by the Hubble Space Telescope suggest that the unexpected dimming was probably caused by an immense amount of superhot material ejected into space. The material cooled and formed a dust cloud that blocked the starlight coming from about a quarter of Betelgeuse’s surface.

That we now have three creditable but different theories, all based on evidence, for explaining the dimming that occurred from October 2019 to April 2020 suggests that we really still have no idea what specifically caused it. All three theories however are based on what we do know about Betelgeuse, that it is giant blobby gasbag that has dark starspots on its surface, that has giant convection cells that bubble up from below and release material periodically, and that it pulses in a variety of cycles predictably over time.

It could be any of these phenomenon that caused last year’s dimming, or even a combination of two or more. The information available so far is just too sketchy to pin this down more precisely.

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OSIRIS-REx completes closest sample grab rehearsal

8:45 am

OSIRIS-REx yesterday successfully completed its closest sample grab rehearsal, bringing the spacecraft about 131 feet from the surface of the asteroid Bennu.

The approximately four-hour “Matchpoint” rehearsal took the spacecraft through the first three of the sampling sequence’s four maneuvers: the orbit departure burn, the “Checkpoint” burn and the Matchpoint burn. Checkpoint is the point where the spacecraft autonomously checks its position and velocity before adjusting its trajectory down toward the event’s third maneuver. Matchpoint is the moment when the spacecraft matches Bennu’s rotation in order to fly in tandem with the asteroid surface, directly above the sample site, before touching down on the targeted spot.

Four hours after departing its 0.6-mile (1-km) safe-home orbit, OSIRIS-REx performed the Checkpoint maneuver at an approximate altitude of 410 feet (125 meters) above Bennu’s surface. From there, the spacecraft continued to descend for another eight minutes to perform the Matchpoint burn. After descending on this new trajectory for another three minutes, the spacecraft reached an altitude of approximately 131 ft (40 m) – the closest the spacecraft has ever been to Bennu – and then performed a back-away burn to complete the rehearsal.

During the rehearsal, the spacecraft successfully deployed its sampling arm, the Touch-And-Go Sample Acquisition Mechanism (TAGSAM), from its folded, parked position out to the sample collection configuration. Additionally, some of the spacecraft’s instruments collected science and navigation images and made spectrometry observations of the sample site, as will occur during the sample collection event. These images and science data were downlinked to Earth after the event’s conclusion.

The actual sample-grab-and-go attempt is scheduled for October 20th.

The short video below the fold shows spacecraft as it makes its closest approach. From the youtube page:
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Martian sand traps and elongated dunes

9:14 am

Elongated dunes on Mars
Click for full image.

Cool image time! The photo to the left, rotated, cropped, and reduced to post here, was taken on June 23, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). I was attracted by the uncaptioned image’s title, “Elongating Linear Dunes at Meroe Patera.” What are elongating linear dunes?

The photo shows two such dunes, stretching out to the southwest away from the pile of sand that abuts the cliff to the northwest. Unlike most dunes, which usually form and travel in groups, these for some reason form single straight lines extending for some distance.

I contacted the scientist who requested this image, Joel Davis of the Natural History Museum in London, hoping he could answer some questions about these strangely shaped dunes, and discovered that he was studying this exact subject for a paper since published. As noted in the paper’s introduction,
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Snapped cable damages Arecibo radio telescope

12:25 pm

One of the cables that supports the central platform above the Arecibo Observatory’s giant dish snapped yesterday, damaging the dish and shutting down operations.

The break occurred about 2:45 a.m. When the three-inch cable fell it also damaged about 6-8 panels in the Gregorian Dome and twisted the platform used to access the dome. It is not yet clear what caused the cable to break. “We have a team of experts assessing the situation,” says Francisco Cordova, the director of the observatory. “Our focus is assuring the safety of our staff, protecting the facilities and equipment, and restoring the facility to full operations as soon as possible, so it can continue to assist scientists around the world.”

The radio telescope has not much luck the past few years. It was badly damaged and shut down for a long time after Hurricane Maria in 2017, with repairs from that still on-going.

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The edge of Mars’ south polar layered cap

12:10 pm

The edge of the Martian south pole layered deposits
Click for full image.

Cool image time! The photo to the right, rotated and cropped to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on April 10, 2020, and shows the edge of what scientists have dubbed Mars’s south polar layered deposits. The high point, towards the south, is at the bottom, and the terraced layers descend downward to the plains as you move up the image, to the north.

In essence, this spot is the edge of the southern ice cap, though unlike the north polar ice cap, this edge is not the edge of the visible ice cap, but the edge of a much larger field of layered deposits of mixed dust and ice. In the north the ice cap almost entirely covers these layered deposits. In the south the residual ice cap does not. Instead, the layered deposits extend out far beyond the smaller residual ice cap.

The map below provides the geography of the south pole, with the location of this image indicated by the blue cross.
» Read more

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TESS completes primary mission

9:33 am

Having now imaged 75% of the entire night sky and completing its primary mission, scientists have now begun the extended mission for the Transiting Exoplanet Survey Satellite (TESS), designed to look for transiting exoplanets.

TESS monitors 24-by-96-degree strips of the sky called sectors for about a month using its four cameras. The mission spent its first year observing 13 sectors comprising the southern sky and then spent another year imaging the northern sky.

Now in its extended mission, TESS has turned around to resume surveying the south. In addition, the TESS team has introduced improvements to the way the satellite collects and processes data. Its cameras now capture a full image every 10 minutes, three times faster than during the primary mission. A new fast mode allows the brightness of thousands of stars to be measured every 20 seconds, along with the previous method of collecting these observations from tens of thousands of stars every two minutes. The faster measurements will allow TESS to better resolve brightness changes caused by stellar oscillations and to capture explosive flares from active stars in greater detail.

These changes will remain in place for the duration of the extended mission, which will be completed in September 2022. After spending a year imaging the southern sky, TESS will take another 15 months to collect additional observations in the north and to survey areas along the ecliptic – the plane of Earth’s orbit around the Sun – that the satellite has not yet imaged.

So far the telescope has spotted more than 2,100 exoplanet candidates, with 66 confirmed.

All told, TESS has divided the sky into 26 sectors, 13 in the north and 13 in the south. It can only look at one at a time for a month, and scientists use that one month data, collected more than once, to see if there are any changes. Because of the gaps in TESS’s view of each sector, however, it is guaranteed to miss some exoplanets (the majority) whose transits occur when it is not looking.

Imagine if we had 25 more of these space telescopes in orbit, so that each sector could be watched continually. This is totally doable now, and would make it possible to soon create a census of transiting exoplanets across the entire sky.

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Cryovolcanism on Ceres still ongoing?

10:02 am

3D simulation of Occator Crater on Ceres
Click for full 3D simulation image.
Click here for animated movie.

According to a new detailed analysis of data from the Dawn mission, scientists are now postulating that cryovolcanism in Occator Crater on Ceres began immediately after impact about 22 million years ago and has continued in fits and starts since.

Occator Crater was formed about 22 million years ago by a large impact. As in many other impact craters on Earth and on other planets, a central peak was formed, which collapsed again after some time. About 7.5 million years ago, brine rose to the surface within the remnants of the central peak. The water evaporated and certain salts, so-called carbonates, remained. They are responsible for the prominent bright deposits we see today, called Cerealia Facula, in the center of Occator Crater. Due to the loss of material in the interior, the inner part of the crater subsided. A round depression with a diameter of about 15 kilometers formed.

In the following millions of years, activity concentrated mainly on the eastern part of the crater floor. Through cracks and furrows, brine also rose to the surface there and produced further bright deposits, the Vinalia Faculae. About 2 million years ago the center of the crater woke up again: brine rose to the surface and within the central depression a dome of bright material was formed. “This process continued up to a million years ago and maybe even until today,” Dr. Nico Schmedemann from the University of Münster summarizes.

This hypothesis is further supported by second paper that proposes there remains a reservoir of salty underground liquid water in the tiny planet’s interior. Both add weight to the idea that any object in space that is large enough for gravity to force it into a spherical shape is going to behave like a planet, with a complex and active geology.

The first paper has a lot of uncertainty, however, centering entirely on its dependence on crater counts to determine age. While providing a rough age estimate, the method depends on many assumptions, is indirect, and could easily be entirely wrong.

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Ascraeus Mons, Mars’ second highest mountain

3:06 pm

Ascraeus Mons

Today’s cool Mars’ image started out when I came across an interesting image of a depression on the northern flank of the giant Martian volcano Ascraeus Mons, the northernmost of the line of three giant volcanoes just to the east of the biggest of all, Olympus Mons.

To provide context I created an overview showing the entire volcano (with the white rectangle showing the location of the depression image), and suddenly realized that this overview might actually be more interesting to my readers. To the right is that overview of Ascreaus, with a scale across the bottom to indicate the elevation of the mountain above what scientists have determined to be Mars’ pseudo sea level.

Notice that this volcano, the second highest on Mars, rises more than 43,000 feet above the surrounding plains. Its peak is estimated to be about 59,000 feet high, making it taller than Mt. Everest by about 30,000 feet (more than twice its height). Its diameter is approximately 300 miles across, giving it a much steeper profile than the higher but more spread out Olympus Mons. The map below shows this mountain in relation to Olympus as well as its nearby partner volcanoes.
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Hayabusa-2’s future asteroid targets

10:02 am

Link here. There are two prime candidate asteroid targets, both near Earth astroids.

The possible secondary targets include the oblong asteroid 2001 AV43 or the asteroid 1998 KY 26. They’re each about the size of a large house and both orbit the Sun in roughly 500 days. The proposed plan would see Hayabusa 2 arriving at 2001 AV43 in the late 2029 time frame, or reaching 1998 KY 26 in July 2031. Both asteroids have a low enough relative speed relative to the spacecraft to put them within (eventual) reach after Hayabusa 2’s December flyby.

Interestingly, 2001 AV43 will fly 313,000 km from Earth (0.8 times the Earth-Moon distance) on November 11, 2029.

The two asteroids were selected from an initial field of 354 candidates, which was winnowed down based on accessibility and scientific interest. Both are fast rotators, as evidenced by their light curves, each spinning on its respective axis once every 10 minutes. This represents the shortest “day” of any known object in the solar system, suggesting that these asteroids are in fact solid objects and not simply loosely aggregated “rubble piles.” A visit to one of these asteroids would mark the first time a space mission has seen such an enigmatic fast rotator up close.

The asteroid 1998 KY26 is also a possible carbonaceous (C-type) asteroid, and Hayabusa 2’s exploration of such a space rock would be another first.

Going to 1998 KY26 would also require a distant pass of another asteroid. Going to 2001 AV43 would require a fly-by of Venus, which could provide more data on that planet. Based on this information, my guess is that they will opt for 1998 KY26.

The decision must likely be made before Hayabusa-2 drops off its Ryugu samples to Earth on December 6, 2020.

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OSIRIS-REx preps for final rehearsal of sample grab

9:40 am

The OSIRIS-REx science and engineering team is getting ready for its August 11th final rehearsal of the sample grab-and-go at the asteroid Bennu that it plans to do in October.

If the rehearsal goes right, the spacecraft will descend to within 131 feet of the surface of Bennu as it deploys its equipment as if it would continue down to the surface. It will also fly in formation above the Nightingale sample site when it does this, taking the highest resolution images yet of the surface of the asteroid.

It will then back off, returning to its home orbit farther from Bennu. Engineers will then review what happened, and use that data to prepare for the actual sample grab-and-go, set for October 20, 2020.

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Slushy floor of southern Martian crater?

1:45 pm

Knobby floor of southern crater
Click for full image.

The cool image to the right, rotated, cropped, and reduced to post here, shows the northwest section of the floor of a crater in the southern cratered highlands of Mars, in a mountainous region dubbed Claritus Fossae, located south of Valles Marineris. The photo was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on May 14, 2020.

The entire crater floor appears to be covered by these strings of closely-packed knobs, reminiscent of the brain terrain found in the mid-latitude glacial regions of Mars and thought to be the result of underground ice sublimating upward.

Below is the area in the white box, in full resolution.
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Study: Lava tubes on Mars and the Moon will be gigantic

9:34 am

A new study comparing lava tubes on the Earth with those detected from orbit on Mars and the Moon now suggests that tubes on those other worlds will be many times larger than on Earth.

Researchers found that Martian and lunar tubes are respectively 100 and 1,000 times wider than those on Earth, which typically have a diameter of 10 to 30 meters. Lower gravity and its effect on volcanism explain these outstanding dimensions (with total volumes exceeding 1 billion of cubic meters on the Moon).

Riccardo Pozzobon adds: “Tubes as wide as these can be longer than 40 kilometres, making the Moon an extraordinary target for subsurface exploration and potential settlement in the wide protected and stable environments of lava tubes. The latter are so big they can contain Padua’s entire city centre”.

Moreover, the data suggests their roofs, even at this size, will be very stable because of the lower gravity, making them excellent locations for large human colonies.

The researchers also suggest that there are many intact such lava tubes under the mare regions on the Moon, their existence only hinted at by the rare skylights created due to asteroid impact.

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Astronomers use Hubble to detect ozone on Earth

8:57 am

Using the Hubble Space Telescope, scientists have shown that it will be possible to detect ozone in the atmospheres of exoplanets, using larger telescopes while observing transits of those exoplanets across the face of their star.

What the scientists did was aim Hubble at the Moon during a lunar eclipse. Moreover, they timed the observations so that the sunlight hitting the Moon and reflecting back to Earth (and Hubble) had also traveled through the Earth’s atmosphere on its way to the Moon.

They then looked at the spectrum of that light, and were able to glean from it the spectral signal of ozone in the Earth’s atmosphere. When giant ground-based telescopes under construction now come on line in the coming decades they will have the ability to do this with transiting exoplanets.

The measurements detected the strong spectral fingerprint of ozone, a key prerequisite for the presence – and possible evolution – of life as we know it in an exo-Earth. Although some ozone signatures had been detected in previous ground-based observations during lunar eclipses, Hubble’s study represents the strongest detection of the molecule to date because it can look at the ultraviolet light, which is absorbed by our atmosphere and does not reach the ground. On Earth, photosynthesis over billions of years is responsible for our planet’s high oxygen levels and thick ozone layer. Only 600 million years ago Earth’s atmosphere had built up enough ozone to shield life from the Sun’s lethal ultraviolet radiation. That made it safe for the first land-based life to migrate out of our oceans.

“Finding ozone in the spectrum of an exo-Earth would be significant because it is a photochemical byproduct of molecular oxygen, which is a byproduct of life,” explained Allison Youngblood of the Laboratory for Atmospheric and Space Physics in Colorado, USA, lead researcher of Hubble’s observations.

Ozone does not guarantee the presence of life on an exoplanet, but combined with other detections, such as oxygen and methane, would raise the odds significantly.

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Filled and distorted craters on Mars

9:12 pm

A very distorted and filled crater on Mars
Click for full image.

Cool image time! The photo to the right, rotated and cropped to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on May 25, 2020. The entire image was dubbed “Cluster of Filled Craters”, but I decided to highlight the crater of the cluster that was most strangely distorted of them all. The material that fills all the craters in the full image is almost certainly buried ice and is dubbed concentric crater fill by scientists.

This crater is located in the northern lowland plains the mid-latitudes between 30 and 60 degrees, where planetary scientists have found ample evidence of many such filled craters and glaciers.

Not only does the crater’s interior seemed filled with glacial material, its distorted rim suggests that it has been reshaped by glacial activity that might have covered it entirely over the eons as the mid-latitude glaciers of Mars waxed and waned with the extreme shifts that happen regularly to Mars’ rotational tilt. Moreover, there is strong evidence that in these lowland northern plains an underground ice table exists close to the surface, allowing for more distortion over time.

The overview map below provides some location context.
» Read more

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Lightning and mushballs on Jupiter

3:49 pm

Artist's illustration of Jupiter lightning
Click for full illustration.

Using data from Juno, scientists now theorize that Jupiter produces what they dub “shallow lightning” as well as ammonia-water hailstones dubbed “mushballs.”

The image to the right, cropped and reduced to post here, is only an artist’s illustration of the lightning. Sadly Juno’s camera doesn’t have the resolution to capture such flashes.

An unexpected form of electrical discharge, shallow lightning originates from clouds containing an ammonia-water solution, whereas lightning on Earth originates from water clouds.

Other new findings suggest the violent thunderstorms for which the gas giant is known may form slushy ammonia-rich hailstones Juno’s science team calls “mushballs”; they theorize that mushballs essentially kidnap ammonia and water in the upper atmosphere and carry them into the depths of Jupiter’s atmosphere.

As with the InSight results below, there is much uncertainty with these results, especially the hypothesis of mushballs. These features fit their present data from Juno, but we must remember that the data is still somewhat superficial.

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Scientists make first rough estimate of Mars’ internal structure

3:33 pm

Artist's cutaway showing theorized Martian interior
Artist’s cutaway of theorized Martian interior

Using data from InSight’s seismometer, scientists have made their first approximation of the internal structure of Mars.

The first boundary Deng and Levander measured is the divide between Mars’ crust and mantle almost 22 miles (35 kilometers) beneath the lander.

The second is a transition zone within the mantle where magnesium iron silicates undergo a geochemical change. Above the zone, the elements form a mineral called olivine, and beneath it, heat and pressure compress them into a new mineral called wadsleyite. Known as the olivine-wadsleyite transition, this zone was found 690-727 miles (1,110-1,170 kilometers) beneath InSight. “The temperature at the olivine-wadsleyite transition is an important key to building thermal models of Mars,” Deng said. “From the depth of the transition, we can easily calculate the pressure, and with that, we can derive the temperature.”

The third boundary he and Levander measured is the border between Mars’ mantle and its iron-rich core, which they found about 945-994 miles (1,520-1,600 kilometers) beneath the lander. Better understanding this boundary “can provide information about the planet’s development from both a chemical and thermal point of view,” Deng said.

Because they only have one seismometer on the planet, this approximation has a great deal of uncertainty. Only when we have multiple such seismic instruments, scattered across the entire Martian globe, will scientists be able to hone their models more accurate of the planet’s interior.

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The dry barren plains of Tyrrhena Terra

12:20 pm

Tyrrhena Terra badlands
Click for full image.

In a sense today’s cool image is a replay of one I posted in March, showing the dry barren terrain in the vast rough cratered highlands of Tyrrhena Terra, located along the equator of Mars between the giant basins of Isidis and Hellas.

Today’s image on the right, cropped to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter on March 26, 2020, and shows well the barrenness of this region. The surface appears quite solid, like bedrock, rather than the squishy soft surface of the northern lowland plains. Moreover, there is a lot of dust trapped in the low areas between the ridges, forming ripples that new data suggest move slowly across the surface. If you click on the full image, you will see that this terrain is far from local, and goes on in this manner for quite a distance in all directions.

This is a dry and forbidding place, about the size of the American southwest, from Texas to California.

The overview map below provides some context of Tyrrhena Terra’s location on Mars.
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Masks, social distancing, and mass hysteria

4:34 pm

This past weekend Diane and I went hiking, as we try to do at least once a week. With the gyms closed by our petty dictator governor, Republican Doug Ducey, we need to find a way to get out and exercise, both for our sanity and to strengthen our immune systems, since outdoor exercise is probably the most effective way to prevent yourself from getting sick from any respiratory illness.

As we were hiking along a single male hiker, probably in his mid- to late- twenties, approached us from the other direction. When he saw me in the lead, he immediately cringed off to the side of the trail in what seemed literal terror, holding a bandana to his face.

I looked at him in irritation. “You don’t need the mask, we don’t have cooties and we won’t make you sick.”

“I don’t want to make you sick,” he said as I passed him.

“What makes me sick,” I responded as I continued past him down the trail, “is the irrational terror and fear I see in everyone’s eyes, over something that really is not much more different than the flu.”

I will admit to have become somewhat of a cranky grump these days when I see everyone wearing masks. And I feel this way because of the utter mindlessness of mask-wearing. This healthy young hiker, who almost certainly was not contagious in any way with any illness, including COVID-19, was only within four feet of me for about one second. Even if he had COVID-19 and was infectious to me and tried to pant in my face as I went by it would have been almost impossible for him to infect me. We were just not in close enough contact for long enough.

Moreover, he stood there holding the bandana to his mouth and nose, with his hand. That its exactly the wrong thing to do if you want to protect yourself, as your hands are the most likely transmission point for infection, and by pressing his bandana against his face with his hand he risked placing that infection at the very place he breathed.

He might have reduced my chances of getting infected by an infinitesimal amount, but he increased his own risk substantially.

Mask-wearing is just plain irrational, and for intelligent Americans to go along with this silliness is beyond shameful, especially because in almost every jurisdiction, even those that mandate mask use, you can opt out by simply stating you have medical reasons for not wearing a mask, and are not required under HIPPA regulations to even show documentation proving that statement in any way. It must be accepted on its face, without question.

Let’s review the absurdity of this situation, and maybe remind people why it is foolish.
» Read more

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Sunspot update: Hints of the next maximum

11:07 am

It’s time for another monthly sunspot update! NOAA yesterday updated its monthly graph for tracking the Sun’s monthly sunspot activity, and as I do every month, I am posting it below with additional anotations by me to show the past and new solar cycle predictions.

July 2020 sunspot activity

The graph above has been modified to show the predictions of the solar science community for both the previous and upcoming solar maximums. The green curves show the community’s two original predictions from April 2007 for the previous maximum, with half the scientists predicting a very strong maximum and half predicting a weak one. The blue curve is their revised May 2009 prediction. The red curve is the new prediction, first posted by NOAA in April 2020.

July continued the trend from June, with a slight uptick in activity. The SILSO graph below for July illustrates this.
» Read more

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Study: Mars’ meandering canyons formed under ice

9:23 am

A new study comparing Mars’ meandering canyons with those found in the Arctic regions on Earth suggests that the Martian valleys were formed by water melting under large ice sheets, not flowing water on the surface.

A large number of the valley networks scarring the surface of Mars were carved by water melting beneath glacial ice, not by free-flowing rivers as previously thought, according to new research published in Nature Geoscience. The findings effectively throw cold water on the dominant “warm and wet ancient Mars” hypothesis, which postulates that rivers, rainfall and oceans once existed on the red planet.

To reach this conclusion, lead author and postdoctoral research scholar Anna Grau Galofre of Arizona State University’s School of Earth and Space Exploration developed and used new techniques to examine thousands of Martian valleys. She and her co-authors also compared the Martian valleys to the subglacial channels in the Canadian Arctic Archipelago and uncovered striking similarities. The western edge of the Devon ice cap on the Canadian Arctic Archipelago.

I have noted previously on Behind the Black my sense that the planetary science community was beginning to shift away from the hypothesis of flowing liquid surface water on Mars as an explanation for the planet’s riverlike and oceanlike features to some form or ice/glacial activity. For a half century the scientists have tried and failed to come up with some scenario that could allow water to flow on the surface in Mars’ cold climate and thin atmosphere.

Ice or glacial activity rather than flowing liquid water might solve this problem, and today’s paper is a push in this direction.

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New model predicting solar flares is 56% accurate

1:01 pm

The uncertainty of science: Using observations from the space-based Solar Dynamics Observatory (SDO), solar scientists have developed a new model for predicting the biggest solar flares, and have found it to able to predict a big flare about 56% of the time.

Kusano and his team looked at the seven active regions from the last solar cycle that produced the strongest flares on the Earth-facing side of the Sun (they also focused on flares from part of the Sun that is closest to Earth, where magnetic field observations are best). SDO’s observations of the active regions helped them locate the right magnetic boundaries, and calculate instabilities in the hot spots. In the end, their model predicted seven out of nine total flares, with three false positives. The two that the model didn’t account for, Kusano explained, were exceptions to the rest: Unlike the others, the active region they exploded from were much larger, and didn’t produce a coronal mass ejection along with the flare. [emphasis mine]

What they did was apply their model to active regions on the Sun during the last solar maximum to see if it would accurately predict the events we know did happen. The model predicted that big flares would spout from ten of twelve active regions on the Sun during the last solar cycle. In reality, only seven of those twelve active regions produced flares.

The press release minimizes the three false positives, making believe they don’t count in the total. That’s hogwash. The model got it wrong, and so these false positives must be counted just like the two false negatives.

A prediction rate of 56% is barely above random, so this model needs a lot of work. Nonetheless, it is a major step forward, because it is not based on simple statistics — counting the number of big sunspots and the number of big flares and then calculating the percentage that flare — which is how most solar science models are structured, and thus are really meaningless. Instead, this model is based an actual analysis of the behavior of the Sun’s magnetic field in big active regions when solar flares erupt. They are trying to pinpoint the precise conditions that cause the big flares, and appear to be narrowing the conditions successfully.

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Jupiter’s south pole

10:59 am

The storms at the south pole of Jupiter
Click for full image.

Cool image time! The photo to the right, rotated and reduced to post here, was taken by Juno during its 28th close orbital fly-by of Jupiter, and then processed by citizen scientist Hemant Dara.

While not the first Juno image of the poles of Jupiter, this photo illustrates very well the evolution of the gas giant’s deep atmosphere as you move from the equator to the pole. From the equator to the high mid-latitudes the planet’s rotation, producing a day only 10 hours long, organizes that atmosphere into jet streams that form the bands that astronomers have spied from Earth since the first telescopes.

At the pole the influence of that rotation seems to wane, or at least influence the atmosphere differently, so that the storms seem to form randomly and incoherently.

The image also shows that there appear to be several types of storms at the south pole. Some appear as tight spirals, similar to hurricanes. Others appear chaotic, with no consistent shape, almost like clouds on Earth.

The processes that would explain all this are not yet understood, in the slightest, and won’t be until we get orbiters at Jupiter able to watch the atmosphere continuously, as we do here on Earth. Then it will be possible to assemble movies of the formation and dissipation of these storms, and begin (only begin) to decipher what causes them.

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Yutu-2 completes 20th lunar day on Moon

10:28 am

The new colonial movement: The Chinese lunar rover Yutu-2 has completed its 20th lunar day on the farside of the Moon, and has now been put in sleep mode for the long lunar night.

Yutu 2 continued on its planned journey to the northwest of the lander, according to the China Lunar Exploration Program (CLEP). The rover covered 90 feet (27.64 meters) during the lunar day to make a total of 1,610 feet (490.9 m) of roving since setting down on the far side of the moon in January 2019.

The article at the link includes some images, including visual data from the ground-piercing radar that suggests at least four layers in the lunar subsurface.

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Midnight repost: A scientist’s ten commandments

11:59 pm

The tenth anniversary retrospective of Behind the Black continues: The post below, from September 27, 2010, reports on one of the simplest but most profound scientific papers I have ever read. Its advice is doubly needed today, especially commandment #3.

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A scientist’s ten commandments

Published today on the astro-ph website, this preprint by Ignacio Ferrín of the Center for Fundamental Physics at the University of the Andes, Merida, Venezuala, is probably the shortest paper I have ever seen. I think that Dr. Ferrin will forgive me if I reprint it here in its entirety:

1. Go to your laboratory or your instrument without any pre-conceived ideas. Just register what you saw faithfully.

2. Report promptly and scientifically. Check your numbers twice before submitting.

3. Forget about predictions. They are maybe wrong.

4. Do not try to conform or find agreement with others. You may be the first to be observing a new phenomenon and you may risk missing credit for the discovery.

5. Criticism must be scientific, respectful, constructive, positive, and unbiased. Otherwise it must be done privately.

6. If you want to be respected, respect others first. Do not use insulting or humiliating words when referring to others. It is not in accord with scientific ethics.

7. Do not cheat. Cheating in science is silly. When others repeat your experiment or observation, they will find that you were wrong.

8. If you do not know or have made a mistake, admit it immediately. You may say, “I do not know but I will find out.” or “I will correct it immediately.” No scientist knows the answer to everything. By admitting it you are being honest about your knowledge and your abilities.

9. Do not appropriate or ignore other people’s work or results. Always give credit to others, however small their contribution may have been. Do not do unto others what you would not like to be done unto you.

10. Do not stray from scientific ethics.

It seems that some scientists in the climate field (Phil Jones of East Anglia University and Michael Mann of Pennsylvania State University are two that come to mind immediately) would benefit by reading and following these rules.

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Perseverance’s planned journey in Jezero Crater

1:34 pm

Jezero Crater delta
Jezero Crater delta

If all goes right, on February 18, 2021 the rover Perseverance will gently settle down onto the floor of Jezero Crater on Mars. The image to the right is probably the most reproduced of this site, as it shows the spectacular delta that some scientists believe might be hardened mud that had once flowed like liquid or lava from the break in the rim to the west.

They hope to put Perseverance down to the southeast of that delta, as shown in the overview map below.
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Astronomers find freshly fallen meteorites based on tracking their fall

11:36 am

Australian astronomers have found two meteorites on the ground after spotting them in the sky before they fell, with one found only

The first had been spotted in the sky only a few weeks earlier, while the second had been spotted back in November 2019. They had had to postpone the search for the second until the restrictions for the Wuhan flu were lifted.

The discovery of the first was amusing:

Astronomer Dr Hadrien Devillepoix and planetary geologist Dr Anthony Lagain originally went on a reconnaissance mission to assess the latest fall site near Madura, taking drone imagery of the area. Dr Devillepoix said that as they were walking back to their car along the old telegraph track near Madura Cave, they spotted what appeared to be a real meteorite on the ground just in front of them.

“I thought Anthony was playing a prank on me, that he planted one of the fake meteorites we were using for the drone training session. But after a closer inspection, it was evident that the fist-sized, 1.1 kilogram rock we just found was indeed the meteorite we were after,” Dr Devillepoix said. Dr Devillepoix explained that although the rock was very close to the predicted fall position, the team was not expecting to find it that quickly in this bushy terrain.

Based on its track as it fell, the astronomers think it might be from the Aten family of asteroids, which orbit the Sun between Venus and Earth. Such asteroids are hard to find because of the glare of the Sun, and are thus not as well studied. This makes this find even more significant.

Finds like this, which are beginning to happen more and more, are important because, first, the meteorite doesn’t spend much time in the Earth environment, and second, they can precisely identify where the asteroid came from. Both facts allow scientists a much better understanding of the asteroids themselves.

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Neutron star left over from Supernova 1987A?

8:24 am

The uncertainty of science: Two different teams of astronomers are now suggesting that, based on evidence recently obtained by the Atacama Large Millimeter/submillimeter Array (ALMA), a neutron star is what is left over from the star that caused Supernova 1987A, the only naked eye supernova in the past four hundred years.

Recently, observations from the ALMA radio telescope provided the first indication of the missing neutron star after the explosion. Extremely high-resolution images revealed a hot “blob” in the dusty core of SN 1987A, which is brighter than its surroundings and matches the suspected location of the neutron star.

..The theoretical study by Page and his team, published today in The Astrophysical Journal, strongly supports the suggestion made by the ALMA team that a neutron star is powering the dust blob. “In spite of the supreme complexity of a supernova explosion and the extreme conditions reigning in the interior of a neutron star, the detection of a warm blob of dust is a confirmation of several predictions,” Page explained.

These predictions were the location and the temperature of the neutron star. According to supernova computer models, the explosion has “kicked away” the neutron star from its birthplace with a speed of hundreds of kilometers per second (tens of times faster than the fastest rocket). The blob is exactly at the place where astronomers think the neutron star would be today. And the temperature of the neutron star, which was predicted to be around 5 million degrees Celsius, provides enough energy to explain the brightness of the blob.

They haven’t actually gotten any direct evidence of this stellar remnant, so some healthy skepticism is required. At the same time, the data favors this solution, which means the star did not collapse into a black hole when it exploded.

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