Tag: science

A dark dust avalanche on Mars

10:01 am

No dust avalanche

After dust avalanche

Cool image time! The two images to the right, both cropped to post here, were taken six years apart by Mars Reconnaissance Orbiter (MRO) of the western lava slopes of the giant volcano Olympus Mons. They show the appearance of a dark dust avalanche during the interim. As noted by members of the MRO science team.

Dust avalanches create slope streaks that expose darker materials usually hidden below a lighter-toned layer. Cascading fine-grained material easily diverts around boulders or alters direction when encountering a change in slope. The dark steak … is approximately 1 kilometer in length that we didn’t see in a previous image. Past avalanche sites are still visible and fading slowly as dust settles out of the atmosphere and is deposited on the dark streaks over time.

We also see boulders and their shadows that are a meter or greater in size. Movement of any of these boulders down the slope could trigger future avalanches.

The appearance of these Martian dark streaks on slopes is actually not uncommon. As more pictures are taken of Mars scientists are beginning to accumulate a large number all across the Martian surface.

What I find fascinating is the wet look of these dark streaks. Below is a close-up of the new avalanche, near its head.
» Read more

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Europe initiates website to name ExoMars 2020 rover

9:26 am

The European Space Agency has created a website where people can offer their suggestions to name the ExoMars 2020 rover.

Astronaut Tim Peake is leading the hunt for a great moniker. He wants everyone to go to a special website set up for the purpose and enter a suggestion. But don’t think “Spacey McSpaceFace” is a goer because this is not an online poll. All ideas will be put before an expert panel and it is they who will make the final choice.

If all goes right, 2020 should see two new rovers arrive on the Martian surface.

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Most biomedical research cannot be replicated

9:13 am

New studies looking at the work of scientists in the biomedical field has found that their research is difficult if not impossible to replicate, partly because much of their raw data is never made available for other researchers to review.

But over the past several years, a growing contingent of scientists has begun to question the accepted veracity of published research—even after it’s cleared the hurdles of peer review and appears in widely respected journals. The problem is a pervasive inability to replicate a large proportion of the results across numerous disciplines.

In 2005, for instance, John Ioannidis, a professor of medicine at Stanford University, used several simulations to show that scientific claims are more likely to be false than true. And this past summer Brian Nosek, a professor of psychology at the University of Virginia, attempted to replicate the findings of 100 psychology studies and found that only 39 percent of the results held up under rigorous re-testing. “There are multiple lines of evidence, both theoretical and empirical, that have begun to bring the reproducibility of a substantial segment of scientific literature into question,” says Ioannidis. “We are getting millions of papers that go nowhere.”

There’s a lot more. Read it all. It appears that much if not all of biomedical research is suspect. Their conclusions might be correct, but their methods are questionable, at best.

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Hayabusa-2 finds Ryugu covered with scattered large boulders

11:02 pm

Hayabusa-2 has found that the asteroid Ryugu is covered with many scattered large boulders.

The Hayabusa 2 space probe discovered many boulders scattered on the asteroid Ryugu, suggesting it was formed from fragments of other celestial bodies, the Japan Aerospace Exploration Agency (JAXA) said July 19. More than 100 rocks larger than 8 meters in length were confirmed on the surface of the “spinning top” asteroid from images captured by Hayabusa 2, according to JAXA. The largest boulder was about 130 meters in length near the south pole.

The rocks are likely too big to be meteor fragments from collisions with Ryugu, which has a diameter of about 900 meters. “(The finding) is compelling evidence to prove that the Ryugu asteroid was formed by fragments of larger celestial bodies,” said Seiichiro Watanabe, head of the study team and professor of Nagoya University.

The asteroid’s slightly tilted axis of rotation gives Ryugu two seasons: summer and winter. Hayabusa 2 found the temperature ranged from about 20 to 100 degrees on Ryugu’s surface.

Surprise! This finding makes Ryugu very different from every other asteroid previously visited. Most have had relatively smooth surfaces, with lots of dust.

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Dust storm update on Mars

2:03 pm

Link here. This press release basically reviews what each Martian spacecraft, in orbit or on the surface, is doing to study or survive the global dust storm that erupted on Mars in in early June.

The storm itself has not yet eased, and the general expectation is that it will last for a couple of months, through August.

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Global mosiacs of Titan in infrared

8:53 am

Titan in infrared

The Cassini science team today released global infrared mosaics of Titan, created from images accumulated during the more than 100 fly-bys of the moon during the spacecraft’s thirteen years in orbit around Saturn.

The image on the right, cropped and reduced in resolution to post here, is only one such global mosaic. Go to the story to see them all.

Making mosaics of VIMS images of Titan has always been a challenge because the data were obtained over many different flybys with different observing geometries and atmospheric conditions. One result is that very prominent seams appear in the mosaics that are quite difficult for imaging scientists to remove. But, through laborious and detailed analyses of the data, along with time consuming hand processing of the mosaics, the seams have been mostly removed. This is an update to the work previously discussed in PIA20022.

Any full color image is comprised of three color channels: red, green and blue. Each of the three color channels combined to create these views was produced using a ratio between the brightness of Titan’s surface at two different wavelengths (1.59/1.27 microns [red], 2.03/1.27 microns [green] and 1.27/1.08 microns [blue]). This technique (called a “band-ratio” technique) reduces the prominence of seams, as well as emphasizing subtle spectral variations in the materials on Titan’s surface. For example, the moon’s equatorial dune fields appear a consistent brown color here. There are also bluish and purplish areas that may have different compositions from the other bright areas, and may be enriched in water ice.

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New close-up images of Ceres

12:15 pm

Cerealia Facula on Ceres

Cool image time! The image on the right, cropped and reduced in resolution to post here, is one of two images released today by the Dawn science team of the double bright spots found in Occator Crater, taken from the spacecraft’s tight final orbit above Ceres. This image shows what they have dubbed Cerealia Facula. The second image shows Vinalia Faculae.

This mosaic of Cerealia Facula is based on images obtained by NASA’s Dawn spacecraft in its second extended mission, from an altitude as low as about 21 miles (34 kilometers). The contrast in resolution obtained by the two phases is visible here, reflected by a few gaps in the high-resolution coverage. This image is superposed to a similar scene acquired in the low-altitude mapping orbit of the mission from an altitude of about 240 miles (385 km).

Inset of Cerealia Facula

The second image on the left is a crop at full resolution of the area in the white box above. This gives you a taste of the many interesting things found in the full resolution image. For example, the bright spots scattered throughout this image suggest they are recent upwellings from below. The ridgelines in the upper right are either the remains of the water-ice volcano they think once stood here but subsequently slumped back down to form a depression, or pressure ridges being pushed up by later upwellings.

The full image has lots more. So does the image of Vinalia Faculae. Check them out.

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Entire Martian atmosphere appears to act as a single unit

10:32 am

Using ten years of accumulated data from Europe’s Mars Express orbiter scientists have found that the Martian atmosphere appears to behave as a single unit, with changes its upper and lower levels closely connected.

“We discovered a surprising and significant increase in the amount of charged particles in the upper atmosphere during springtime in the Northern hemisphere, which is when the mass in the lower atmosphere is growing as ice sublimates from the northern polar cap,” adds Beatriz.

Mars’ polar caps are made up of a mix of water ice and frozen carbon dioxide. Each winter, up to a third of the mass in Mars’ atmosphere condenses to form an icy layer at each of the planet’s poles. Every spring, some of the mass within these caps sublimates to rejoin the atmosphere, and the caps visibly shrink as a result. “This sublimation process was thought to mostly only affect the lower atmosphere – we didn’t expect to see its effects clearly propagating upwards to higher levels,” says co-author Olivier Witasse of the European Space Agency, and former ESA Project Scientist for Mars Express. “It’s very interesting to find a connection like this.”

The finding suggests that the atmosphere of Mars behaves as a single system.

This finding might also explain why periodically Mars experiences a planet-wide dust storm, as it is doing right now.

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Mars rover update: July 17, 2018

12:35 pm

Summary: Curiosity climbs back up onto Vera Rubin Ridge to attempt its second drillhole since drill recovery, this time at a spot on the ridge with the highest orbital signature for hematite. Opportunity remains silent, shut down due to the global dust storm.

For a list of past updates beginning in July 2016, see my February 8, 2018 update.

Curiosity

Curiosity's travels on and off Vera Rubin Ridge

For the overall context of Curiosity’s travels, see Pinpointing Curiosity’s location in Gale Crater.

In the almost two months since my May 23, 2018 update, a lot has happened, much of which I covered in daily updates. Curiosity found a good drill spot to once again test the new drilling techniques designed by engineers to bypass its stuck drill feed mechanism, and was successful in getting its first drill sample in about a year and a half. The rover then returned uphill, returning to a spot on Vera Rubin Ridge that, according to satellite data, has the highest signature for hematite on the entire ridge. The light green dotted line in the traverse map to the right shows the route Curiosity has taken back up onto Vera Rubin Ridge. The red dotted line shows the original planned route off the ridge and up Mount Sharp.
» Read more

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Astronomers discover 10 more Jupiter moons

9:48 am

Worlds without end: Astronomers, while searching for objects in the Kuiper Belt, have discovered 10 more Jupiter moons.

All the newfound moons are small, between about 1 and 3 kilometres across. Seven of them travel in remote orbits more than 20 million kilometres away from Jupiter, and in the opposite direction from the planet’s rotation. That puts them in the category known as retrograde moons.

The eighth moon stands out because it travels in the same region of space as the retrograde moons, but in the opposite direction (that is, in the same direction as Jupiter’s spin). Its orbit is also tilted with respect to those of the retrograde moons. That means it could easily smash into the retrograde moons, pulverizing itself into oblivion. It may be the leftovers of a bigger cosmic collision in the past, Sheppard says.

Jupiter’s moons are named after gods with connections to the mythological Jupiter or Zeus. Sheppard has proposed naming the oddball Valetudo, after one of Jupiter’s descendants, the Roman goddess of hygiene and health.

The ninth and tenth newfound moons orbit closer to Jupiter, moving in the same direction as the planet.

I predict that these are not the last moons of Jupiter to be discovered. As our observing skills improve, more are certain to pop up.

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A weird lunar lava field

2:43 pm

Weird terrain at Ina on the Moon

Cool image time! The image on the right, reduced and rotated 180 degrees to post here, comes from a recent release for Lunar Reconnaissance Orbiter (LRO). It shows a flow of lava that partly covers an older terrain.

Some scientists propose that Ina formed as very young (less than 100 million years) volcanic eruptions because only a few larger impact craters (>20 m) have formed on its surface. Others believe it is quite ancient (3.5 billion years), possessing highly unusual physical properties that stifle the formation of normal impact craters. At least everybody agrees it was formed as basalt was erupted to the surface! But how and when Ina formed remains open.

Ina’s morphology is so unusual that it is easy to see inverted topography – that is, craters appear as bubbles rather than bowls! Think of Ina as a cast iron frying pan with freshly poured pancake batter; the wiggly textured material is the frying pan and the bulbous smoother mounds are the batter.

The image to the right has been rotated 180 degrees so that my mind at least can see it with the craters as bowls and the uplifted smooth lava as uplifted. If this doesn’t work for you, click on the link and look at the original image.

While some scientists think the lava flows are recent, no one knows at present the origins of the rougher terrain that the lava has partly obscured.

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Binary asteroid imaged by radio telescopes

10:18 am

Three radio telescopes have successfully imaged the rotation of a binary asteroid, the fourth such binary so far discovered.

On June 21, the asteroid 2017 YE5 made its closest approach to Earth for at least the next 170 years, coming to within 3.7 million miles (6 million kilometers) of Earth, or about 16 times the distance between Earth and the Moon. On June 21 and 22, observations by NASA’s Goldstone Solar System Radar (GSSR) in California showed the first signs that 2017 YE5 could be a binary system. The observations revealed two distinct lobes, but the asteroid’s orientation was such that scientists could not see if the two bodies were separate or joined. Eventually, the two objects rotated to expose a distinct gap between them.

Scientists at the Arecibo Observatory in Puerto Rico had already planned to observe 2017 YE5, and they were alerted by their colleagues at Goldstone of the asteroid’s unique properties. On June 24, the scientists teamed up with researchers at the Green Bank Observatory (GBO) in West Virginia and used the two observatories together in a bi-static radar configuration (in which Arecibo transmits the radar signal and Green Bank receives the return signal). Together, they were able to confirm that 2017 YE5 consists of two separated objects. By June 26, both Goldstone and Arecibo had independently confirmed the asteroid’s binary nature.

The new observations obtained between June 21 and 26 indicate that the two objects revolve around each other once every 20 to 24 hours. This was confirmed with visible-light observations of brightness variations by Brian Warner at the Center for Solar System Studies in Rancho Cucamonga, California.

I have embedded below the fold a short video that includes the radio images showing this rotation. Most cool!
» Read more

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Astronomers track neutrino from galaxy 3.7 billion light years away

10:04 am

Using multiple telescopes astronomers have successfully tracked the source of a neutrino that was detected on September 22 2017 by the IceCube neutrino telescope in Antarctica to a galaxy 3.7 billion light years away.

Because scientists on the IceCube experiment had worked out the path the particle took through their subterranean ice instrument, astronomers knew where in the sky to look for the particle’s source. A string of early observations came up blank, but days later Nasa’s Fermi Gamma-ray Space Telescope spotted the likely source: a flaring “blazar”.

Most galaxies are thought to have spinning supermassive black holes at their centres. But some of these black holes appear to pull in material at ferocious rates, a process that simultaneously sends streams of highly energetic particles out into space. Such galaxies are called blazars, although the term only applies when one of these streams is directed straight at Earth.

The blazar that appears to have sent the neutrino our way lies 3.7bn light years from Earth, just off the left shoulder of the constellation of Orion. While a single detection is not strong evidence, the IceCube scientists went back through their records and found a flurry of neutrinos coming from the same spot over 150 days in 2014 and 2015.

This I think is the first time scientists have linked a neutrino to its source, outside our solar system. Most neutrino detections come from the Sun. That they could trace this one back to a blazar so far away means their neutrino telescopes are now becoming sensitive enough to find and study the neutrinos coming from other sources.

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A science journal describes how evil Trump is destroying EPA

9:31 am

Link here.

If you have no idea why we have Trump, and why we are likely to get more of him, read this article from the science journal Nature. It is a carefully written screed, written entirely from the point of view of those hostile to Trump and his effort to rein in the EPA’s regulatory culture. No one is interviewed to give the Trump perspective, and even if some had been, the author is so certain that Trump is evil and wrong in his efforts that I am sure the Trump perspective would have been misinterpreted, or even slandered. (This I am sure is why the article says that EPA management did not “respond to requests to comment on the article’s allegations.” The allegations were already set. Nothing anyone said from the administration would change those conclusions.)

Still, I am certain the author could have gotten opinions from some of the skeptical scientists whom the Trump administration has brought in to advise EPA. None however were interviewed.

What is most embarrassing about the article is its description of two of the main changes the Trump administration has imposed on EPA to widen and make more transparent the scientific work it does. First,
» Read more

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Conflict in Hubble constant increases with new data from Hubble and Gaia

8:52 am

The uncertainty of science: New data from the Hubble Space Telescope and Gaia continues to measure a different Hubble constant for the expansion rate of the universe, when compared with data from the Planck space telescope.

Using Hubble and newly released data from Gaia, Riess’ team measured the present rate of expansion to be 73.5 kilometers (45.6 miles) per second per megaparsec. This means that for every 3.3 million light-years farther away a galaxy is from us, it appears to be moving 73.5 kilometers per second faster. However, the Planck results predict the universe should be expanding today at only 67.0 kilometers (41.6 miles) per second per megaparsec. As the teams’ measurements have become more and more precise, the chasm between them has continued to widen, and is now about 4 times the size of their combined uncertainty.

The problem really is very simple: We haven’t the faintest idea what is going on. We have some data, but we also have enormous gaps in our knowledge of the cosmos. Moreover, most of our cosmological data is reliant on too many assumptions that could be wrong, or simply in error. And the errors can be tiny and still throw the results off by large amounts.

The one thing that good science and skepticism teaches is humbleness. Do not be too sure of your conclusions. The universe is a large and complex place. It likes to throw curve balls at us, and if we swing too soon we will certainly miss.

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Ghost dunes on Mars

9:40 am

Scientists have found Martian pits formed by the leftover remains of dunes that long ago blew away.

Scientists have discovered hundreds of crescent-shaped pits on Mars where sand dunes the size of the U.S. Capitol stood billions of years ago. The curves of these ancient dune impressions record the direction of prevailing winds on the Red Planet, providing potential clues to Mars’s past climate, and may hold evidence of ancient life, according to a new study detailing the findings in the Journal of Geophysical Research: Planets, a publication of the American Geophysical Union.

Ghost dunes are the negative space left behind by long-vanished sand dunes. Lava or water-borne sediments partially buried the dunes and hardened, preserving the dunes’ contours. Wind subsequently blew sand off the exposed tops and scoured it out from inside, leaving a solid mold in the shape of the lost dune.

The claim that these geological features “may hold evidence of ancient life” is pure hyperbole, and absurd. However, the features are important because they will help date the sediment or lava flows around them, while also providing markers to help understand the history of the Martian climate.

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Spiders on Mars!

9:34 am

spiders on Mars

Cool image time! Today’s release of new captioned images from the high resolution camera on Mars Reconnaissance Orbiter (MRO) included a wonderful image of the melting carbon dioxide cap of Mars’s south pole. On the right is a cropped portion of the full image, showing what the MRO scientists nickname spiders, features that appear as the CO2 begins to turn into gas.

But these aren’t actual spiders. We call it “araneiform terrain,” to describe the spider-like radiating channels that form when carbon dioxide ice below the surface heats up and releases. This is an active seasonal process we don’t see on Earth. Like dry ice on Earth, the carbon dioxide ice on Mars sublimates as it warms (changes from solid to gas) and the gas becomes trapped below the surface.

Over time the trapped carbon dioxide gas builds in pressure and is eventually strong enough to break through the ice as a jet that erupts dust. The gas is released into the atmosphere and darker dust may be deposited around the vent or transported by winds to produce streaks. The loss of the sublimated carbon dioxide leaves behind these spider-like features etched into the surface.

The image above shows older spiders, formed during past seasonal events. If you click on the image you can see the full image, which shows darker spiders produced by this season’s cycle.

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Global topographic maps of Pluto and Charon

9:14 am

Using data and images from New Horizons scientists have now produced the first global topographic maps of Pluto and Charon.

Obviously, the resolution for the maps of both planets is very uneven, since the spacecraft only saw part of each planet at high resolution during its fly-by. Nonetheless, they note some of the more interesting details revealed:

These maps reveal a rich variety of landforms on both Pluto and Charon. The topographic maps confirm that the highest known mountains on Pluto are the Tenzing Montes range, which formed along the southwestern margins of the frozen nitrogen ice sheet of Sputnik Planitia. These steep-sided icy peaks have slopes of 40° or more and rise several kilometers above the floor of Sputnik Planitia. The highest peak rises approximately 6 kilometers (3.7 miles) above the base of the range, comparable to base-to-crest heights of Denali in Alaska, and Kilimanjaro in Kenya. Pluto’s mountains must be composed of stiff water ice in order to maintain their heights, as the more volatile ices observed on Pluto, including methane and nitrogen ice, would be too weak and the mountains would collapse.

The topographic maps also reveal large-scale features that are not obvious in the global mosaic map. The ice sheet within the 1000-kilometer (625-mile) wide Sputnik Planitia is on average 2.5 kilometers (1.5 miles) deep while the outer edges of the ice sheet lie an even deeper 3.5 km (or 2.2. miles) below Pluto’s mean elevation, or ‘sea level’ surface. While most of the ice sheet is relatively flat, these outer edges of Sputnik Planitia are the lowest known areas on Pluto, all features that are evident only in the stereo images and elevation maps. The topographic maps also reveal the existence of a global-scale deeply eroded ridge-and-trough system more than 3000 kilometers (or 1864 miles) long, trending from north-to-south near the western edge of Sputnik Planitia. This feature is the longest known on Pluto and indicates that extensive fracturing occurred in the distant past. Why such fracturing occurred only along this linear band is not well understood.

On Charon the topographic maps also reveal deep depressions near the north pole that are ~14 kilometers (8.7 miles) deep, deeper than the Marianas Trench on Earth. The equatorial troughs that form the boundary between the northern and southern plains on Charon also feature high relief of ~8 kilometers. The mapping of fractured northern terrains and tilted crustal blocks along this boundary could be due to cryovolcanic resurfacing, perhaps triggered by the foundering of large crustal blocks into the deep interior of Charon. The rugged relief also indicates that Charon retains much of its original topography caused by its history of fracturing and surface disruption.

These maps are obviously only our first stab at mapping both planets. We will need orbiters around both to truly detail their surface features.

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Mars 2020 gets fourth candidate landing site

9:04 am

The science team for the next American Mars rover, Mars 2020, has decided to consider a fourth candidate landing site, located between two other candidate sites.

The site has been dubbed “Midway,” because it’s roughly halfway between two other candidate landing locations — Jezero delta and Northeast Syrtis. The third previously identified candidate is the Columbia Hills region of Gusev Crater, which NASA’s now-defunct Spirit rover explored after touching down in January 2004.

Jezero, Northeast Syrtis and Columbia Hills were selected as finalists at the third 2020 rover landing site workshop, which was held in February 2017.

Midway has the same morphologic units as Northeast Syrtis and is relatively close to Jezero, explained John Mustard, a professor in the Department of Earth Environmental and Planetary Sciences at Brown University in Providence, Rhode Island. “It has emerged from Mars 2020 science team members I believe brainstorming on possibly getting two birds with one rover,” Mustard told Inside Outer Space.

Based on this story, it sounds to me as this new site has emerged as the favorite. It would put the rover down in the transition zone between Mars’s northern low plains and its southern highlands, an area where evidence of the receding shoreline of any past intermittent ocean might exist. It would also allow it to study geology similar to two previous candidate sites.

One problem they may have is that this candidate site has not yet been photographed in detail by Mars Reconnaissance Orbiter’s (MRO) high resolution camera, as have the other sites. They will need to get time on MRO to do this in order to make sure this site is acceptable.

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Sunspot update for June 2018: Activity increases again

5:56 pm

NOAA today posted its monthly update of the solar cycle, covering sunspot activity for June 2018. Below is this month’s annotated graph.

For the third straight month the Sun showed a small increase in sunspot activity. The pattern also continued to follow the two-week-on/two-week-off pattern of activity caused by the Sun’s 27-day rotation, as I described in my update last month.

June 2018 sunspot activity

The graph above has been modified to show the predictions of the solar science community. The green curves show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction. The yellow line compares the present activity with the activity during solar minimum in 2008 and 2009.

This pattern is continuing. As of today, there have been no sunspots since June 28, almost two weeks. I would not be surprised if some sunspots appeared within the next week, especially because today’s image of the Sun from Solar Dynamic Observatory shows bright faculae rotating into view. Faculae are, like sunspots, a sign of solar magnetic activity. The two usually go together.

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The first American dogs were different, and arrived a very long time ago

9:23 am

New genetic research using buried dogs found at two sites in Illinois suggests that the first American dogs came over from Siberia over 16,000 years ago, and were genetically distinct from European dogs.

In the 1960s and 1970s, archaeologists excavated two sites in western Illinois, where ancient hunter-gatherers collected shellfish from a nearby river and stalked deer in surrounding forests. These people also appear to have buried their dogs: One was found at a site known as Stilwell II, and four at a site called Koster, curled up in individual gravelike pits.

Radiocarbon analysis of the bones reveals that they are around 10,000 years old, making these canines the oldest dogs known in the Americas, researchers report on the bioRxiv server. It also makes these the oldest solo dog burials anywhere in the world. The Stilwell II dog was about the size of an English setter, whereas the Koster dogs were smaller and slenderer, says the study’s lead author, Angela Perri, a zooarchaeologist at Durham University in the United Kingdom. “It wouldn’t be surprising if they were all used as hunting dogs.” But where did they come from in the first place?

A second study, published today in Science, may have the answer. A large, international team of researchers sequenced DNA from the mitochondria, or cellular power plants, of 71 North American and Siberian dog bones—including from one of the Koster dogs—dated from about 10,000 to 1000 years ago. When they compared this material, which is passed down only by the mother, to that of 145 modern and ancient dogs, they discovered that the ancient American dogs have a genetic signature not found in any other canines.

There is much uncertainty still about the dates, but not about the genetics. The dogs were larger, resembles wolves, and even howled instead of barked. They were wiped out after the arrival of the Europeans in American, probably because of disease.

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3D image of Ryugu

4:57 pm

The lead guitarist of the rock band Queen, Brian May, is also an astronomer, and he has taken Hayabusa-2’s first full close-up image of Ryugu and produced a 3D image of the asteroid.

If you have red/blue 3D glasses you should definitely click on the link and view the image. The asteroid appears much more elongated back to front than it appears in the flat image.

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Astronomers dispute existence of galaxy without dark matter

10:40 am

The uncertainty of science: A new analysis by astronomers disputes the conclusion of different astronomers earlier this year that they had found a galaxy that lacked any dark matter.

The original paper from March based its stunning claim of a dark-matter-free galaxy on the way clusters of stars moved through the thin, diffuse galaxy called NGC1052–DF2: They appeared to move at exactly the speed Einstein’s equations of general relativity would predict based on the visible matter (so, slower than they would if the galaxy held dark matter).

This new paper on arXiv suggested otherwise: First, the authors pointed out that NGC1052–DF2 was already discovered way back in 1976 and has previously been referred to by three different names: KKSG04, PGC3097693 and [KKS2000]04.

Then, using those names and then finding all the available data on the galaxy, the researchers argued that the researchers from the March paper simply mismeasured the distance between that galaxy and Earth. This means the galaxy is probably much closer to us than the original researchers thought.

Astronomers calculate the mass of galaxies based on the objects’ brightness and distance. If the galaxy examined in the paper is closer to Earth than previously thought, then its dimness means it’s also much less massive than researchers thought. And at the newly calculated, lighter mass, all the other features of the galaxy make a lot more sense, the researchers in the new paper said. Its globular clusters aren’t moving slowly because they’re in some strange dark matter-desert; instead, they’re moving at the regular speed for a very lightweight galaxy, the arXiv authors said.

To put it bluntly, the astronomers don’t have enough solid data to decide this issue one way or the other. Moreover, the dispute indicates once again that the whole dark matter theory itself is based on very limited data with large margins of error. It might be the best theory we’ve got to explain the data we have, but no good scientist takes it too seriously. We just don’t know enough yet.

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Kepler on verge of death

10:04 am

The Kepler space telescope is now almost out of fuel, and scientists have ceased science observations to devote the telescope’s last days downloading its last 51 days of data.

The telescope lasted far longer than planned, and discovered thousands of exoplanets. Its archives will be producing new discoveries for decades. And a new exoplanet space telescope, TESS, is already in orbit to take over.

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Searchers find fragment of asteroid that hit Earth June 2nd

10:00 am

Researchers and local park volunteers in Botswana’s Central Kalahari Game Reserve on July 8 announced the discovery of a fragment from an asteroid that hit the Earth June 2 only eight hours after it was discovered.

“The biggest uncertainty we faced was to determine where exactly the meteorites fell,” says Peter Jenniskens a subject expert of the SETI Institute in California, who traveled to Botswana to assist in the search. He teamed up with Oliver Moses of the University of Botswana’s Okavango Research Institute (ORI), to gather security surveillance videos in Rakops and Maun to get better constraints on the position and altitude of the fireball’s explosion. Team member Tim Cooper of the Astronomical Society of Southern Africa calibrated videos to the south.

After disruption, the asteroid fragments scattered over a wide area, blown by the wind while falling down. Calculations of the landing area were done independently by the NASA-sponsored group headed by Jenniskens, as well as by Esko Lyytinen and Jarmo Moilanen of the Finnish Fireball Network. These calculations were defining the fall area well enough to warrant the deployment of a search expedition.

The first meteorite was found after five days of walking and scouring a landscape of sand, thick tall grass, shrubs and thorn bushes by a team of geoscientists from the Botswana International University of Science and Technology (BUIST), the Botswana Geoscience Institute (BGI) and from ORI, guided by Jenniskens. The Botswana Department of Wildlife and National Parks granted access and deployed their park rangers to provide protection and participate in the search. BUIST student Lesedi Seitshiro was first to spot the stone.

This is only the second time in history that a small asteroid observed in space was recovered following its impact on Earth.

I have amateur astronomer friends who attempted to do this exact thing, here in Tucson. We actually went out one day hunting for a meteorite they had tracked, but were unsuccessful in finding anything. To have had success we would have likely required more search time and a better constraint on the asteroid’s landing zone.

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Galaxies collide!

7:07 am

Using data from then space telescope Gaia, astronomers have identified evidence that 8 to 10 billion years ago the Milky Way collided with a dwarf galaxy.

The astronomers propose that around 8 billion to 10 billion years ago, an unknown dwarf galaxy smashed into our own Milky Way. The dwarf did not survive the impact: It quickly fell apart, and the wreckage is now all around us.

“The collision ripped the dwarf to shreds, leaving its stars moving in very radial orbits” that are long and narrow like needles, said Vasily Belokurov of the University of Cambridge and the Center for Computational Astrophysics at the Flatiron Institute in New York City. The stars’ paths take them “very close to the center of our galaxy. This is a telltale sign that the dwarf galaxy came in on a really eccentric orbit and its fate was sealed.”

It is thought that this dwarf galaxy was quite large for a dwarf galaxy.

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A star that shoots cosmic rays

7:02 am

New data from the space telescope NuSTAR suggests that the giant star Eta Carina, expected to be a supernova sometime in the future, emits cosmic rays, some of which reach the Earth.

The cosmic rays are produced by shock waves resulting from the clash between the intense solar winds of the system’s two stars.

Go to the link to see a truly beautiful image of this star system. You will immediately see that it is a system exploding.

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More close-up images of Ceres

6:48 am

On Monday the Dawn science team released more close-up images of Ceres, taken from Dawn’s final close orbit of the dwarf planet, with the focus of this release Occator Crater and its bright spots.

The current images now show numerous sections of Occator Crater from an altitude of 35 kilometers and with a resolution less than 5 meters per pixel. “The data exceeds all our expectations,” Dr. Andreas Nathues from the MPS, Framing Camera Lead Investigator, says. In the new images, the surface is now ten times better resolved than in the best images from the previous three years.

Impressive avalanches reveal themselves in the new views of the eastern wall of Occator Crater: there are clear signs that material has been recently moving down the slopes; some of it remains stuck halfway. Other images allow a close look at the interplay of bright and dark material in the eastern part of the crater. “We now hope to understand how the bright deposits outside the crater center came about – and what they tell us about Ceres’ interior,” says Nathues. Various analyses of the past years suggest that Ceres has a water-rich crust. Small impacts and landslides regularly expose ice at the surface, which produces a thin exosphere of water vapor.

I have posted some of these images previously, but there are several new ones at the link.

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Ancient rain on Mars?

9:05 am

New data suggests that the many meandering canyons on Mars were partly formed by rain.

Although Mars is cold and dry today, channels on its surface look as if running water shaped them, leading researchers to think the planet was warm and wet in the past. But scientists have struggled to determine whether that water fell from the sky as rain or seeped upward from the ground.

To discern the water’s source, Hansjoerg Seybold at the Swiss Federal Institute of Technology (ETH) Zurich and his colleagues analysed the geometry of Martian valley channels. The channels branch off at relatively narrow angles, as do waterways in arid landscapes on Earth, such as the US Southwest. More-humid landscapes with a lot of groundwater — the Amazon rainforest, for example — host river channels that branch at wider angles.

The discovery bolsters the idea that the Martian channels were carved by surface runoff rather than by water percolating from below.

The paper itself is behind a paywall, so it is unclear whether they included in their analysis the consequences of Mars’s lighter gravity. Regardless, this result is intriguing, even if it has a lot of uncertainty.

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