Tag: science

New evidence: dark energy might not exist

5:46 pm

The uncertainty of science: New evidence once again suggests that the assumptions that resulted in the invention of dark energy in the late 1990s might have been in error, and that dark energy simply might not exist.

New observations and analysis made by a team of astronomers at Yonsei University (Seoul, South Korea), together with their collaborators at Lyon University and KASI, show, however, that this key assumption is most likely in error. The team has performed very high-quality (signal-to-noise ratio ~175) spectroscopic observations to cover most of the reported nearby early-type host galaxies of SN Ia, from which they obtained the most direct and reliable measurements of population ages for these host galaxies. They find a significant correlation between SN luminosity and stellar population age at a 99.5% confidence level. As such, this is the most direct and stringent test ever made for the luminosity evolution of SN Ia. Since SN progenitors in host galaxies are getting younger with redshift (look-back time), this result inevitably indicates a serious systematic bias with redshift in SN cosmology. Taken at face values, the luminosity evolution of SN is significant enough to question the very existence of dark energy. When the luminosity evolution of SN is properly taken into account, the team found that the evidence for the existence of dark energy simply goes away.

…Other cosmological probes, such as CMB (Cosmic Microwave Background) and BAO (Baryonic Acoustic Oscillations), are also known to provide some indirect and “circumstantial” evidence for dark energy, but it was recently suggested that CMB from Planck mission no longer supports the concordance cosmological model which may require new physics. Some investigators have also shown that BAO and other low-redshift cosmological probes can be consistent with a non-accelerating universe without dark energy. In this respect, the present result showing the luminosity evolution mimicking dark energy in SN cosmology is crucial and is very timely.

There was also this story from early December, also raising questions about the existence of dark energy.

Bottom line: The data that suggested dark energy’s existence was always shallow with many assumptions and large margins of uncertainty. This research only underlines that fact, a fact that many cosmologists have frequently tried to sweep under the rug.

Dark energy still might exist, but it behooves scientists to look coldly at the data and always recognize its weaknesses. It appears in terms of dark energy the cosomological community is finally beginning to do so.

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Hubble captures giant galaxy

2:01 pm

Giant spiral galaxy imaged by Hubble
Click for full image.

Cool image time! The above image, cropped and reduced to post here, was compiled from images taken by the Hubble Space Telescope in 2018 of one of the largest known spiral galaxies.

One of the most photogenic is the huge spiral galaxy UGC 2885, located 232 million light-years away in the northern constellation, Perseus. It’s a whopper even by galactic standards. The galaxy is 2.5 times wider than our Milky Way and contains 10 times as many stars, about 1 trillion. This galaxy has lived a quiescent life by not colliding with other large galaxies. It has gradually bulked up on intergalactic hydrogen to make new stars at a slow and steady pace over many billions of years. The galaxy has been nicknamed “Rubin’s galaxy,” after astronomer Vera Rubin (1928 – 2016). Rubin used the galaxy to look for invisible dark matter. The galaxy is embedded inside a vast halo of dark matter. The amount of dark matter can be estimated by measuring its gravitational influence on the galaxy’s rotation rate.

This majestic spiral galaxy might earn the nickname the “Godzilla Galaxy” because it may be the largest known in the local universe. The galaxy, UGC 2885, is 2.5 times wider than our Milky Way and contains 10 times as many stars.

But it is a “gentle giant,” say researchers, because it looks like it has been sitting quietly over billions of years, possibly sipping hydrogen from the filamentary structure of intergalactic space. This fuels modest ongoing star birth at half the rate of our Milky Way. In fact, its supermassive central black hole is a sleeping giant, too; because the galaxy does not appear to be feeding on much smaller satellite galaxies, it is starved of infalling gas.

There are mysteries here, many of which we are as yet entirely unaware of yet.

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Yutu-2 completes 13th lunar day

9:02 am

China’s Yutu-2 lunar rover and its lander Chang’e-4 have completed their thirteenth lunar day on the far side of the Moon and have been placed in sleep mode.

During the twelve lunar day the rover traveled about 12 meters, or about 40 feet.

The rover has found materials from deep inside the moon that could help unravel the mystery of the lunar mantle’s composition and the formation and evolution of the moon and the earth. Using data obtained by the visible and near-infrared spectrometer installed on Yutu-2, Chinese scientists found that the lunar soil in the landing area of the Chang’e-4 probe contains olivine and pyroxene which came from the lunar mantle deep inside the moon.

Due to the complicated geological environment and the rugged and heavily cratered terrain on the far side of the moon, the rover drives slowly but steadily and is expected to continue traveling on the moon and make more scientific discoveries.

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Betelguese fades a full magnitude

12:46 am

Long term observations of the red giant star Betelguese have found it to have faded a full magnitude in the past few months, dropping it from 6th brightest in the sky to the 21st.

You will see a lot of bad journalism related to this story, hyping the fact that Betelguese is considered one of the top nearby stars to someday in the far future go supernovae. However, the recent change in brightness is unlikely related to this and is nothing unusual, as the star fluctuates regularly.

The current faintness of Betelgeuse appears to arise from the coincidence of the star being near the minimum light of the ~5.9-yr light-cycle as well as near, the deeper than usual, minimum of the ~425-d period.

The star is definitely interesting, because it is so large (if placed in our solar system its surface would be around the orbit of Jupiter) and so defuse, more like a partly filled gasbag. However, the odds of it going supernovae in the near future is quite unlikely.

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Protesters continue to shut down TMT

5:12 pm

Mob rule: Though an agreement has been reached between the anti-telescope protesters and the mayor of the Big Island to move a tent blocking the access road to Mauna Kea, the deal also provided that no construction will proceed, even though the consortium that is building the Thirty Meter Telescope (TMT) has gotten legal permission to do so.

They agreed to move the so-called “kupuna tent,” referring to the Hawaiian word for elder, as part of a deal announced by Big Island Mayor Harry Kim.

In exchange, Kim promised protesters there will be no attempts to deliver construction equipment to the telescope site “anytime soon,” according to Kim’s offer letter to Noe Noe Wong-Wilson, one of the protest leaders who is considered a kupuna. “I, Mayor Kim give you my personal assurances that no attempt will be made to move TMT construction equipment up the mountain for a minimum of two months,” his letter said.

Legally Kim doesn’t really have the right to do this, unless Hawaii has decided to completely abandon the rule of law. Then again, Hawaii has decided to abandon the rule of law, as it now lets mobs, not the law, determine who can build where and when.

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ExoMars2020 passes new parachute tests

9:07 am

Revisions to Europe’s ExoMars2020 parachutes have successfully passed tests at JPL in California.

Working with Nasa, ESA made modifications to the way the parachutes are released from the bag, which avoids creating so much friction. Using a special rig at JPL, the parachutes have now been tested up to their expected extraction speed of just over 200km/h with no sign of damage. Further confirmatory tests will now take place.

Time remains very short however. The launch window for ExoMars2020 is this coming summer.

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A minor eruption on the Sun

3:03 pm

How about another cool image, this time a movie taken by Solar Dynamics Orbiter (SDO) back in August 13, 2018 of what they call a minor eruption on the surface of the Sun.

Because the movie is a somewhat large file, I have embedded it below the fold. Or you could go here to see a higher resolution version. This is the description by the SDO science team:

This close-up of the Sun from a two-hour period on Aug 13, 2018 shows a minor eruption of charged particles rising up and twisting about before falling back into the Sun. Imaged in extreme ultraviolet light, these kinds of events are difficult to see except when they occur along the sun’s edge, also known as the limb. At its peak the plasma rises several times the diameter of Earth. [emphasis mine]

» Read more

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Giant scallops on Mars

2:48 pm

Scallops on Mars
Click for full image.

It’s a slow news week, with the too much partying only real space news today the expected third launch of China’s Long March 5 rocket (supposedly scheduled for this morning but so far no word). (To my gentle reader: For some reason I have been losing a day during this whole week, always thinking that Christmas was on Thursday and that today was Friday. Thus my error in thinking the Long March 5 flight was today. It is tomorrow morning. Forgive me for my absent-mindedness.) So let’s look at a cool image!

The photo on the right, cropped and reduced to post here, was taken my the high resolution camera on Mars Reconnaissance Orbiter (MRO) on October 8, 2019. Entitled “Scalloped Depressions in Utopia Planitia,” it shows a strangely eroded surface in the northern lowlands of Mars, where an intermittent ocean might have once existed.

The location of these scallops is shown to the right.

Location of scallops in Utopia Planitia

I have taken the same overview map used from two recent cool image posts, showing how these scallops relate in location to the strange crater in Utopia Planitia as well as the glacial-surrounded mesa in Protonilus Mensae.

In caves, scallops like this form from water or wind flow, but when they do, they are all oriented the same way. Here the scallops are at different orientations, terracing down from the center of the image. In this case it appears that scientists believe [pdf] the formation process is related to the sublimation of underground ice at this location.

According to [one hypothesis] scallop formation should be ongoing at the present time. Sublimation of interstitial ice could induce a collapse of material, initially as a small pit, then growing southward because of greater solar heating on the southern side. Nearby scallops would coalesce together as can be seen to have occurred.

What is most cool is that the geologists think the process that forms these scallops is related to the same processes that cause the formation of the swiss cheese landforms in the south polar regions.

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Crater in the Martian northern lowlands

11:32 am

Crater in Utopia Planitia
Click for original full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on October 26, 2019. It shows a crater in the western edge of Utopia Planitia, the largest and deepest region of the Martian northern lowlands where it is theorized that an intermittent ocean might have once existed.

My first uneducated guess at looking at this image is that the impact occurred in some sort of wet slushy mud or ice, which then melted and filled the crater interior, ponding in the crater’s center as it froze.

A more educated guess, based on what I have learned in the past year, is not much different. The crater is located at 40 degrees north latitude and therefore sits in the middle of the mid-latitude band where scientists think there are a lot of buried inactive glaciers.

Overview map

The map to the right, revised from my December 20, 2019 post about glaciers flowing off the slopes of a mid-latitude mesa, illustrates this even more clearly.

This crater, indicated by the white cross, sits at approximately the same latitude as that mesa and its glaciers in Protonilus Mensae. It also sits at in an area where accumulated data from several spacecraft have mapped a lot of water ice, close to the surface.

Thus, it is reasonable to suppose that the impact that made this crater pushed into that ice-table, melting the water which subsequently froze and then subsided downward into the ground to form the crater’s central ponded features.

Or to put it as I did initially, the impact smashed into some wet slushy mud/ice, melting it so that it filled the crater interior to then freeze as we see it.

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A deep dive into Valles Marineris

2:56 pm

Dunes on the floor of Valles Marineris
Click for full image.

The vastness of Mars is sometimes hard to fathom. While the planet is much smaller than Earth, its entire global surface is approximately the same as the Earth’s land area. This is a lot of territory. It took humanity many tens of thousands of centuries to expand outward to settle all of it. It took even longer before humanity was successfully able to map all of the Earth so that its entire surface was known to all humans, a task that was only completed a handful of centuries ago.

While we now have the technology to quickly map the entire globe of a planet like Mars, the devil is always in the details. At this time the resolution of our global maps give us only a glimpse of the Martian surface.

The image to the right, reduced and cropped to post here, is a good example. Taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on October 30, 2019, it shows a set of large dunes on the northern floor of a side canyon on Mars that is part of Coprates Chasma, a canyon that forms only a small part of the vast Valles Marineris canyon system east of the giant volcanoes of the Tharsis Bulge.

The sand of these dunes is mostly volcanic material, dark basalt that was deposited as lava from those giant volcanoes, then later ground down in landslides and erosion to be recycled as sand that formed dunes trapped within the canyon bottom. The dunes themselves are slowly moving eastward, driven mostly by the predominate west-to-east winds that blow down this side canyon of Coprates Chasma. The motion is very slow, so slow that even though the image title is “Coprates Chasma Dune Changes”, I was unable to spot any changes when I compared this 2019 image with a photo taken in June 2019.

To find out what had changed, I contacted Matt Chojnacki of the Lunar and Planetary Laboratory at the University of Arizona, who has been studying the nature of the sand dunes in Valles Marineris. After making a quick preliminary blink test using more sophisticate tools than I have available, he found “minor advancements. The rocks move a bit too in places.” Without a full analysis he also added, “I can tell some dune crests have moved to the east.”

The research by Chojnacki and others has found that the dunes within Valles Marineris are in many ways different than dunes found elsewhere in the mid-latitudes on Mars, suggesting that being trapped within this giant canyon has produced some specific regional features. They tend to be darker, the canyon contains several sand dune seas, called ergs (only seen elsewhere on Mars in the polar regions), and the dunes tend to be more hardened, so that they change relatively little when compared to similar dunes elsewhere on Mars.

These particular dunes in Coprates Chasma however are not hardened, since if so they would have been covered by the landslides and material that comes down from the canyon’s nearby northern slopes. Instead, they move, but appear to move far slower than similar dunes elsewhere on Mars.

To me, this image provides a good vehicle for getting a sense of the size of Valles Marineris. Coprates Chasma itself only one of about a dozen named sections of the entire Valles Marineris canyon system, and this particular image shows only the floor of a side canyon of Coprates. The map below gives an overview of the entire system.
» Read more

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Movie of Jupiter’s south pole storms

9:03 am

Clip from animation of Jupiter's south polar storms

Cool image time! Citizen scientist Gerald Eichstädt has used images taken by Juno of Jupiter’s south polar storms to produce an animation that shows the evolution of those storms over a short time period.

The movie is more a computer model than an assemblage of images.

A fluid dynamical 2D model rotating with Jupiter’s System III rotation rate is started with a map of PJ19 (Juno’s 19th close approach) vorticity measurements of the south polar region between 75 and 90 degrees south (azimuthal, equidistant, planetocentric) as initial condition. The vorticity map is based on a sequence of PJ19 JunoCam images.

Relative vorticities are encoded in color, blue for cyclonic, orange for anticyclonic relative vorticity. The animated gif covers 48 hours, with one frame per real-time hour. Played with 25 fps, the result is a 90,000-fold time-lapsed animation.

I have embedded the animation below the fold. It is quite impressive.
» Read more

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Buried glaciers flowing off of Martian mesa

1:55 pm

Glacial flow off of mesa
Click for full image.

Cool image time! Planetary geologists now think that the mid-latitudes of Mars contain many buried and inactive glaciers, formed several million years ago when the planet’s inclination was more than 50 degrees [pdf], rather than the 25 degrees it is now. At that time the mid-latitudes were actually colder than the poles, and water would sublimate from the poles to the colder mid-latitudes to pile up as snow and glaciers.

With today’s 25 degree inclination those mid-latitude glaciers are inactive, and have been so for several million years. It might even be that Mars’ water is beginning a shift back to the poles, but this is uncertain. If anything the planet is presently in a balance, and won’t start transferring water back to the poles until its inclination drops closer to zero.

The image to the right, taken by the high resolution camera on Mars Reconnaissance Orbiter (MRO) on September 23, 2019, is of one of those glacial flows, coming off a mesa in a region called Protonilus Mensae, located in the transition zone between the southern highlands and the northern lowland plains where an intermittent ocean might have once existed.

Much of the geology of Protonilus Mensae is chaos terrain, places where the surface has eroded along angled fissures to form many mesas. The overview map below focuses in on the particular mesa where this flow is located. The red boxes indicate all the MRO images taken of this mesa, with the image above indicated by the black dot.
» Read more

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Megadunes in the giant canyon of Mars’ north polar icecap

1:02 pm

Martian megadunes at the beginning of summer
Click for full image.

Cool image time! The photo to the right, cropped and reduced to post here, was taken by the high resolution camera of Mars Reconnaissance Orbiter (MRO) on September 15, 2019, right at the beginning of summer at the north polar icecap of Mars.

Without a larger context it is very difficult to figure out what this image shows. The image title, “Seasonal Changes of Chasma Boreale Megadunes,” gives us some basic clues. The streaks of black and dark grey are giant dunes, with this image showing their trailing edge. The darkest streaks are likely places where the thin winter mantle of dry ice has begun to sublimate away with the coming of spring, exposing the darker sand dunes below. The surrounding flat white areas are either the permanent water ice of the icecap or the surface of the lowland northern plains that surround that icecap.

The montage below shows a series of monitoring photos, beginning in 2018 during the last Martian summer and continuing through the start and middle of the spring and ending with the photo above. It shows the seasonal evolution of that upper carbon dioxide dry ice mantle, which reveals the darker dunes below as that dry ice mantle sublimates away.
» Read more

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Martian impacts and streaks

12:18 pm

Slope-streaked crater on Mars
Click for full image.

In the most recent image download from the high resolution camera on Mars Reconnaissance Orbiter (MRO), there was the cool image to the right, reduced and cropped to post here, of a crater that appeared to have hundreds and hundreds of slope streaks along its inner slopes.

Slope streaks are quite mysterious. They are found in the equatorial regions as dark (though sometimes light) streaks on steep slopes, appearing throughout the year and slowly fading over time. They also appear to be a geological phenomenon unique to Mars. Nothing on Earth or any other planet appears to correspond.

As such, their nature and cause remains unknown, though there are a bunch of theories, with the most popular being that these are a kind of dust avalanche. They are always found in connection with dust-covered terrain, but they also make no significant topological change to the surface, other than brightness.

The slope streaks in this crater are especially intriguing, because of the number of streaks. In digging further into the MRO archive I found a number of images of this crater and its surrounding terrain. It appears that sometime before 2012 there was a relatively recent impact close to the exterior of the eastern rim of this crater. The image below, taken in 2014 by MRO, shows this impact as the large dark splotch, with the new crater indicated by the arrow..
» Read more

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North magnetic pole continues its drift

3:52 pm

The uncertainty of science: The newest 2020 version of the World Magnetic Model, released on December 10, 2019, shows that the north magnetic pole is continuing its unprecedented drift eastward and away from the Canadian Arctic.

A new and updated version of the WMM is released every five years. The latest WMM2020 model will extend to 2025.

Since Earth’s magnetic field is created by its moving, molten iron core, its poles aren’t stationary and they wander independently of each other. Since its first formal discovery in 1831, the north magnetic pole has traveled around 1,400 miles (2,250 km). This wandering has been generally quite slow, allowing scientists to keep track of its position fairly easily. Since the turn of the century, this speed has increased.

The WMM2020 forecasts that the northern magnetic pole will continue drifting toward Russia, although at a slowly decreasing speed—down to about 40 km per year compared to the average speed of 55 km over the past twenty years.

Though we know the magnetic field is produced by the magnetism related to the Earth’s molten iron core, scientists do not have a solid understanding of the details, including why the drift of the pole has accelerated this century as well as shifted eastward.

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The importance of small telescopes to science and civilization

10:58 am

The main cluster of telescopes, on Mount Lemmon
Largest cluster of telescopes on Mount Lemmon, six visible with three just out of view.

On December 11, 2019 I was kindly given a personal tour by Alan Strauss, director of the Mount Lemmon Sky Center, of the telescopes located on the mountaintops of the Santa Catalina Mountains overlooking Tucson. Strauss runs the educational outreach program for the University of Arizona astronomy department and the Steward Observatory, both of which operate the mountaintop facility.

The telescopes, numbering almost a dozen, are in two groups, two telescopes on the peak of Mount Bigelow and the rest clustered on the higher peak of Mount Lemmon. None are very gigantic by today’s standards, with their primary mirrors ranging in size from 20- to 61-inches. For comparison, the largest operating telescope in the world on the Canary Islands is 409 inches across. Hubble has a 94-inch mirror. And the new giant telescopes under design or being built have mirrors ranging from 842 inches (Giant Magellan) to 1,654 inches (European Extremely Large Telescope).

Thus, the small telescopes in the Santa Catalinas generally don’t make the news. They are considered passe and out-of-date, not capable of doing the kind of cutting edge astronomy that all the coolest astronomers hunger for.

Yet, without them, we likely would not have future astronomers. » Read more

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Scientists reject discovery of biggest known black hole

9:20 am

The uncertainty of science: In three new papers published this week astronomers have found that the announced discovery in early December of the biggest super-massive black hole ever found, 70 times the mass of the Sun, does not hold up.

In a recent study (a peer-reviewed study published Nov. 27), a team of scientists reported the discovery of the binary system LB-1, which contains a star and, according to the findings, a black hole companion 70 times the mass of our sun. This was major news, a stellar-mass black holes (black holes formed by the gravitational collapse of a star) are typically less than half that massive. But while the study, led by Jifeng Liu, of the National Astronomical Observatory of China (NAOC) of the Chinese Academy of Sciences, was exciting, it was also wrong.

Three new papers came out this week that reexamined the findings from Liu’s study, and these studies say that LB-1’s black hole isn’t actually all that massive.

The new papers find that a closer look at the data finds that it wasn’t doing what the initial researchers thought.

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Maven makes first map of Mars’ high altitude winds

9:11 am

High altitude wind patterns on Mars

Scientists using the Martian orbiter Maven have produced the first global map of the high altitude wind circulation of Mars.

The measurements of winds that were recently mapped above Mars were found at an altitude range of about 140-240 kilometers (85-150 miles) above the planet’s surface.

The wind data has been gathered by the Neutral Gas and Ion Mass Spectrometer (NGIMS). NGIMS’ original purpose was to determine the structure and composition of the Martian atmosphere by measuring in it the amounts of ions (electrically charged particles) and gases. However, although it was not originally designed to do so, in April 2016, the MAVEN team began using NGIMS to observe horizontal winds. Pausing normal collection of data, scientists on Earth programmed the instrument to nod back and forth so that it could detect the direction of winds along its track.

By combining data from many tracks as MAVEN orbits Mars, scientists slowly built up a map of wind behavior. This led to a startling discovery: the wind patterns actually correlated with the Martian topography below.

They have found that even at this high altitude the winds shift around the high volcanoes of the Tharsis Bulge.

To my eye, the wind pattern seen in the image, taken from the video at the link, is remarkably similar to the global wind patterns found on Venus, forming a widening V-pattern moving from east to west. Though the two are vastly different, the similarity is quite intriguing.

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