Tag: astronomy

TESS in safe mode

9:43 am

NASA today revealed that on April 8, 2024 its TESS space telescope went into safe mode, for reasons that are not yet understood.

NASA’s TESS (Transiting Exoplanet Survey Satellite) entered into safe mode April 8, temporarily interrupting science observations. The team is investigating the root cause of the safe mode, which occurred during scheduled engineering activities. The satellite itself remains in good health.

The spacecraft itself remains healthy and they expect to resume science operations “in the coming days.”

That safe mode occurred while “scheduled engineering activities” were ongoing suggests that the two are linked. The lack of any details from NASA further suggests that someone did a “oops!” during those activities, and they are now scrambling to fix things.

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A whirlpool half-hidden by dust

10:23 am

A whirlpool half-hidden by dust
Click for original image.

Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope and shows us a magnificent spiral galaxy about 100 million light years away that also has very active nucleus at its center as well as many star-forming regions (in blue) in its outer arms.

That we do not see the same blue spiral arms on the right side of the photo is not because they are lacking, but because a very large stream of dust blocks our view.

This dark nebula is part of the Chamaeleon star-forming region, itself located only around 500 light-years from us, in a nearby part of the Milky Way galaxy. The dark clouds in the Chamaeleon region occupy a large area of the southern sky, covering their namesake constellation but also encroaching on nearby constellations, like Apus. The cloud is well-studied for its treasury of young stars, particularly the cloud Cha I, which has been imaged by Hubble and also by the … James Webb Space Telescope.

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Lunar Reconnaissance Orbiter snaps a smeared image of South Korea’s Danuri lunar obiter

10:04 am

Danuri as seen by LRO
Click for original image.

Cool image time! On March 5 to March 6, 2024, the orbits of NASA’s Lunar Reconnaissance Orbiter (LRO) and South Korea’s Danuri orbiter had three close approaches, during which LRO had a chance to snap pictures of Danuri as it zipped by in the opposite direction.

The first image is to the right, cropped but expanded to post here.

The flight paths of the two vehicles were nearly parallel but in opposite directions, resulting in extreme relative velocity. The LROC NAC exposure time was very short, only 0.338 milliseconds. But still, Danuri was smeared by a factor greater than 10x in the downtrack direction.

…On the first opportunity, LRO was slewed 43 degrees to capture Danuri from a distance of 5.0 kilometers

Of the three pictures taken, this one appears the best. In all three cases, the fast relative speed was too fast for the camera shutter, so that Danuri’s image was smeared as you see.

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Today’s eclipse

9:49 am

The next eclipses to cross the U.S.
Map by Michael Zeiler (GreatAmericanEclipse.com). Click for original.

Today a solar eclipse will cross some of the most populated areas of Mexixo, the United States, and Canada, as shown on the map to the right.

We shall not see such an event in North America again until 2046, and that will only cover a small part of the Pacific northwest. If you have never seen such an event, get your eclipse glasses (essential if you don’t want to go blind), take some time off of work, and go see it today. This link from Sky & Telescope covers about everything you need to know.

The experience is very hard to describe, though I tried when Diane and I traveled to South Bend, Idaho, in 2017 to experience that eclipse. As I wrote,

Totality was amazing. I was amazed by two things. First, how quiet it became. There were about hundred people scattered about the hotel lawn, with dogs and kids playing around. The hotel manager’s husband set up speakers for music and to make announcements, but when totality arrived he played nothing. People stopped talking. A hush fell over everything. Moreover, I think we somehow imagine a subconscious roar from the full sun. Covered as it was, with its soft corona gleaming gently around it, it suddenly seemed still.

Secondly, the amazing unlikeliness of the Moon being at just the right distance and size to periodically cause this event seemed almost miraculous. Watching it happen drove this point home to me. And since eclipses themselves have been a critical event in the intellectual development of humanity, helping to drive learning and our understanding of the universe, it truly makes me wonder at the majesty of it. I do not believe in any particular religion or their rituals (though I consider the Bible, the Old Testament especially, to be a very good manual for creating a good life and society), but I do not deny the existence of a higher power. Something made this place, and set it up in this wonderous way. Today’s eclipse only served to demonstrate this fact to me again.

I am sure your impressions will be unique to you.

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Engineers confirm IXPE is fixed and resuming science observations

10:00 am

Engineers have now confirmed the software fix they sent to the IXPE space telescope on March 26, 2024 has worked, and have taken the telescope out of safe mode so that it can resume science observations.

The IXPE mission is now observing a new transient X-ray source – Swift J1727.8–161 – a candidate accreting black hole. The source has recently begun producing jets of material moving at a fraction of the speed of light. The IXPE observations will help to understand accretion onto black holes, including potentially revealing how the relativistic jets are formed.

The telescope observes the universe in X-rays, but does so by observing its polarization. This approach provides information not seen in direct observations.

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Interacting galaxies

9:27 am

Interacting galaxies
Click for original image.

Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope as part of a dark energy survey. It shows two galaxies very close together, their perpheries only about 40,000 light years apart, with the larger galaxy about the size of the Milky Way.

For comparison, the Large Magellanic Cloud (LMC) is about 167,000 light years from the Milky Way, more than four times farther that this satellite galaxy. Yet the satellite galaxy here appears much larger than the LMC, having a central core that the LMC lacks. From the caption:

Given this, coupled with the fact that NGC 5996 is roughly comparable in size to the Milky Way, it is not surprising that NGC 5996 and NGC 5994 — apparently separated by only 40 thousand light-years or so — are interacting with one another. In fact, the interaction might be what has caused the spiral shape of NGC 5996 to distort and apparently be drawn in the direction of NGC 5994. It also prompted the formation of the very long and faint tail of stars and gas curving away from NGC 5996, up to the top right of the image. This ‘tidal tail’ is a common phenomenon that appears when galaxies get in close together, as can be seen in several Hubble images.

In this single picture we are witnessing evidence of a process that has been going on for likely many millions of years.

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The remnant of the supernova from 1181, as seen in multiple wavelengths

9:44 am

Supernova remnant as seen in multiple wavelengths
Click for original image.

Using a number of different telescopes and observing in many wavelengths outside the visible spectrum, astronomers have produced a new composite image of the remnant of a supernova that was detected in the year 1181 and remained visible to the naked eye for about six months.

That composite picture is to the right, cropped and reduced to post here. From the press release:

X-ray observations by ESA’s XMM-Newton (blue) show the full extent of the nebula and NASA’s Chandra X-ray Observatory (cyan) pinpoints its central source. The nebula is barely visible in optical light but shines bright in infrared light, collected by NASA’s Wide-field Infrared Space Explorer (red and pink). Interestingly, the radial structure in the image consists of heated sulfur that glows in visible light, observed with the ground-based Hiltner 2.4 m telescope at the MDM Observatory (green) in Arizona, USA, as do the stars in the background by Pan-STARRS (white) in Hawaii, USA.

Because the remnant is so dim in visible light, it has taken years of searching to locate it.

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The spiraling magnetic field surrounding the Milky Way’s central supermassive black hole

9:19 am

The magnetic field lines surrounding Sagittarius A*
Click for original image.

Astronomers have now produced the first detailed image of polarized light surrounding the Milky Way’s central supermassive black hole, dubbed Sagittarius A* (pronounced “Sagittarius A-star”) which in turn maps out the spiraling field lines of that black hole’s magnetic field.

The image to the right, reduced to post here, shows that image. From the press release:

“What we’re seeing now is that there are strong, twisted, and organized magnetic fields near the black hole at the center of the Milky Way galaxy,” said Sara Issaoun, CfA NASA Hubble Fellowship Program Einstein Fellow, Smithsonian Astrophysical Observatory (SAO) astrophysicist, and co-lead of the project. “Along with Sgr A* having a strikingly similar polarization structure to that seen in the much larger and more powerful M87* black hole, we’ve learned that strong and ordered magnetic fields are critical to how black holes interact with the gas and matter around them.”

Light is an oscillating, or moving, electromagnetic wave that allows us to see objects. Sometimes, light oscillates in a preferred orientation, and we call it “polarized.” Although polarized light surrounds us, to human eyes it is indistinguishable from “normal” light. In the plasma around these black holes, particles whirling around magnetic field lines impart a polarization pattern perpendicular to the field. This allows astronomers to see in increasingly vivid detail what’s happening in black hole regions and map their magnetic field lines.

Despite this similarlity, it still remains a mystery why the much larger M87 black hole is very active while Sagittarius A’ remains generally quiet.

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Engineers resolve issue on IXPE space telescope

9:01 am

Engineers have resolved the issue on the IXPE (Imaging X-ray Polarimetry Explorer) space telescope that was jumbling the data it was sending to Earth, and expect to return it to full science operations shortly.

On March 26, using procedures developed following that previous interruption, the team initiated a spacecraft avionics reset to address the issue, which put IXPE into a planned safe mode. The team has confirmed that IXPE is once again transmitting valid telemetry data and is now working to resume science operations, in as rapid and safe a manner as possible. The spacecraft is in good health.

The “previous interruption” was in 2023. In both cases it appears that simply rebooting the telescope’s software fixed the problem.

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The tangled view of astronomers

11:06 am

A protostar in formation
Click for original image.

The uncertainty of science: The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of a survey of young stars surrounded by an edge-on dust disk. From the caption:

FS Tau is a multi-star system made up of FS Tau A, the bright star-like object near the middle of the image, and FS Tau B (Haro 6-5B), the bright object to the far right that is partially obscured by a dark, vertical lane of dust. The young objects are surrounded by softly illuminated gas and dust of this stellar nursery. The system is only about 2.8 million years old, very young for a star system. Our Sun, by contrast, is about 4.6 billion years old.

The blue lines on either side of that vertical dust lane are jets moving out from FS Tau B. The caption says their asymetrical lengths are likely due to ” mass is being expelled from the object at different rates,” but it just as easily be caused by the angle in which we see this object, making the nearer jet seem longer than the one behind.

That astronomers cannot move around such an object and see it from many angles explains the headline of this post. We can only see astronomical objects from one angle, and when they are complex objects such as this one, a large part of the research problem is disentangling the shapes we see into a coherent picture. Spectroscopy helps a lot, as it provides information about the speed and direction of different parts of the object, but even this can be enormously complicated and difficult to interpret.

Remember these facts when you read news reports about astronomical research. No matter how certain the press release sounds, its certainty is always tempered by many unknowns, some very pedestrian but fundamental.

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Citizen scientist project discovers 16 active asteroids

10:39 am

A project that has enlisted approximately 8,300 ordinary citizens to review more than 430,000 photos taken by a telescope in Chile has discovered sixteen asteroids that produce comae and tails like comets.

Identifying and tracking active asteroids whose activity specifically appears to be due to the sublimation of ice – known as main-belt comets – is a particular interest of the project team, as it is an essential part of understanding the abundance and distribution of volatile material like ice in the Solar System.

…The project, utilizing publicly available Dark Energy Camera (DECam) data from the Victor M. Blanco telescope in Chile, involved the examination of more than 430,000 images of known minor planets by 8,300 volunteers, where images identified by citizen scientists as being likely to contain active asteroids were then passed on to the science team for confirmation and additional analysis.

You can read the research paper here. If you want to participate, the Active Asteroids project is still on-going, and can be accessed here.

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A relatively dim star is expected to become one of the brightest in the sky later this year

9:49 am

As it has done twice before at intervals of 80 years, a relatively dim star is expected to go nova later this year, becoming for a short time one of the brightest stars in the sky.

Located in the Northern Crown constellation, T Coronae Borealis (T CrB) is a pretty average looking star, most of the time. With a brightness of about magnitude +10, it’s right on the limits of what you could see with a pair of binoculars, and even if you do go looking there’s not much to see.

At least, that’s the case for about 79 out of 80 years. But on that 80th year, the star suddenly brightens drastically up to around magnitude +2, which puts it on par with the north star Polaris. That makes it one of the brightest stars in the night sky, easily visible with the naked eye even when washed out by city lights. This once-in-a-lifetime outburst last occurred in 1946, and before that 1866.

And lucky for stargazers, T CrB seems to be about two years ahead of schedule, with astronomers predicting it will flare up again between March and September 2024. It’ll appear as a bright ‘new’ star for a few days with the naked eye, and a little over a week with binoculars, before it settles down again for another few decades. Astronomers noticed last year that T CrB had started to dim, which data from 1945 showed preceded the last brightening event.

The star is actually a binary, made up of a white dwarf and a red giant. The white dwarf is pulling material from the red giant, and as that new material piles up, it eventually gathers enough mass to go critical and produce a thermonuclear explosion. The result is a nova, a smaller version of a supernova that unlike supernovae occurs repeatedly.

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ESA: Euclid vision cleared after being fogged by ground ice, after launch

9:13 am

The European Space Agency (ESA) today announced that engineers have successfully “de-iced” the optics of its new Euclid space telescope that developed after it was launched in July 2023.

It was always expected that water could gradually build up and contaminate Euclid’s vision, as it is very difficult to build and launch a spacecraft from Earth without some of the water in our planet’s atmosphere creeping into it. For this reason, there was an ‘outgassing campaign’ shortly after launch where the telescope was warmed up by onboard heaters and also partially exposed to the Sun, sublimating most of the water molecules present at launch on or very near Euclid’s surfaces. A considerable fraction, however, has survived, by being absorbed in the multi-layer insulation, and is now being slowly released in the vacuum of space.

After a huge amount of research – including lab studies into how minuscule layers of ice on mirror surfaces scatter and reflect light – and months of calibrations in space, the team determined that several layers of water molecules are likely frozen onto mirrors in Euclid’s optics. Likely just a few to few tens of nanometres thick – equivalent to the width of a strand of DNA – it’s a remarkable testament to the mission’s sensitivity that it is detecting such tiny amounts of ice.

While Euclid’s observations and science continue, teams have come up with a plan to understand where the ice is in the optical system and mitigate its impact now and in the future, if it continues to accumulate.

It appears this new process has worked, according to a short update at the link.

Normally spacecraft are vented both on the ground during thermal testing, as well as when they reach orbit. It appears some of these normal procedures were either insufficient for Euclid’s needs, or threatened its optics if done as usual. This press release suggests that Euclid required very targeted venting processes that would not harm its sensitive optics, and that the procedures have worked.

I must admit I am suspicious of these claims. During development and after launch Euclid has had a number of problems. First, back in 2017 the NASA instrument on the telescope had to be completely rebuilt when it was found to be defective. Second, after launch engineers discovered unexpected light leaks on the mirror that now limit where it can look. Third, the telescope required a software patch to fix its pointing system, which was confusing cosmic rays for guide stars, causing it to shift positions randomly.

I can’t help wondering if this icing on the mirrors was also due, not to actual planning as suggested by ESA’s press release, but to poor ground testing and engineering that missed what is a common problem on spacecraft and thus required a post-launch improvised fix. I admit I might be wrong, but I still wonder.

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Gehrels Swift space telescope now in safe mode

9:33 am

The Gehrels Swift space telescope, used to get real time observations of gamma ray bursts and other high energy deep space events, is presently in safe mode due to the failure of one of its three gyroscopes.

On March 15, NASA’s Neil Gehrels Swift Observatory entered into safe mode, temporarily suspending science operations due to degrading performance from one of its three gyroscopes (gyros), which are used to point the observatory for making observations. The rest of the spacecraft remains in good health.

Swift is designed to successfully operate without one of its gyros if necessary; however, a software update is required. The team is working on the flight software update that would permit the spacecraft to continue science operations using its two remaining gyros.

The telescope has been operating in orbit for nearly twenty years, far longer than originally planned. Its observations were crucial in discovering that gamma ray bursts occur at vast distances and involve either the core collapse of a star or the merger of two neutron stars.

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Scientists: DART impact of Dimorphos changed its orbit and reshaped the asteroid

9:18 am

Dimorphos shape change
Click for original graphic.

According to a new study, the DART impact of Dimorphos in September 2022 not only shortened its orbit around the larger asteroid Didymos, it reshaped the asteroid itself, warping its widest point sideways from its equator.

You can read the paper here.

More important, the scientists found that the changes evolved over time.

Over the following weeks, the asteroid’s orbital period continued to shorten as Dimorphos lost more rocky material to space, finally settling at 11 hours, 22 minutes, and 3 seconds per orbit – 33 minutes and 15 seconds less time than before impact. This calculation is accurate to within 1 ½ seconds, Naidu said. Dimorphos now has a mean orbital distance from Didymos of about 3,780 feet (1,152 meters) – about 120 feet (37 meters) closer than before impact.

Similarly, the reshaping of the asteroid into its present shape took time. As the scientists noted in their conclusion, “it takes time for a binary system to settle after a kinetic impact event.”

Because of Dimorphus’s rubble pile nature, its shape and orbit should continue to evolve over the coming decades, as more of the ejecta from the impact slowly falls back onto its surface and the asteroid surface adjusts over time. This in turn should also effect the orbit, though by only very tiny amounts.

I continue to wonder if the entire solar orbit of this asteroid binary system was impacted at all by these changes. Any changes would likely be tiny, but it is important to know to see if such an impact can actually do such a thing. To find out will take several more years, as ground telescopes continue to track the asteroid.

In October 2024 the European probe Hera will launch on a mission to this asteroid binary, with its arrival expected in December 2026. At that time we will get a much better look at both asteroids and how the impact affected them.

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Betelgeuse dimming again

10:00 am

Betelqeuse
An optical image of Betelgeuse taken in 2017 by a ground-based
telescope, showing its not unusual aspherical shape.
Click for original image.

It appears that the red giant star Betelgeuse is once again dimming, as it did in 2019-2020.

Betelgeuse, located in Orion’s right shoulder, ordinarily shines at magnitude +0.4, a close match to neighboring Procyon in Canis Minor. But since late January it’s lost some of its luster — at least a third of a magnitude’s worth. That may not sound like much especially given the star’s variable nature, but the red supergiant star is currently the faintest it’s been in the past two years.

Betelgeuse is less like a stable star and more like a gasbag in weightlessness, its shape bouncing in and out as convection bubbles from within push their way to the surface. In some cases, as in 2019-2020, a burst of a bubble releases dust and material, which scientists believe acted to block the star’s light at that time. The dimming now could be for the same reason. Or it could be because the star’s brightness is fundamentally variable. For years it reliably pulsed every 400 days, though that variation pattern now seems to have vanished since 2020.

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Lucy’s first encounter with an asteroid produced surprises

12:39 pm

Dinkinesh, with Salam

At the 55th annual Lunar and Planetary Science Conference presently being held in Texas, the science team for the Lucy asteroid mission presented their first papers outlining what they learned during the spacecraft’s first asteroid encounter, flying past the main belt asteroid Dinkinesh on November 1, 2023.

To the right is the the best image taken at closest approach, at about 270 miles distance, annotated to include the analysis of Dinkinesh’s shape by scientists. As noted in the summary paper [pdf], the asteroid is about a half mile in diameter, and appears to have an equatorial ridge, similar to the ridges found on the near-Earth rubble-pile asteroids Bennu or Ryugu. Dinkinesh is not a rubble pile, however. Though boulder-strewn, it appears more solid, and even has what the scientists call a longitudinal trough, as indicated in the picture.

The ridge overlays the trough implying that it is the younger of the two structures. However, there is as yet no information to better constrain their relative ages, and thus they could potentially have formed in the same event. Indeed, Dinkinesh’s ridge and trough are likely the result of mass failure and the reaccretion of material, and may both be linked to the formation of Selam.

That flyby had produced one major surprise, the existence of a smaller satellite asteroid orbiting Dinkinesh, now dubbed Selam. It is shown in the lower left, as it appeared from behind the main asteroid as Lucy flew past. A later picture however revealed an even greater surprise.
» Read more

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Hubble and Webb confirm decade-long conflict in universe’s expansion rate

8:58 am

The uncertainty of science: New data from both the Hubble and Webb space telescopes has confirmed Hubble’s previous measurement of the rate of the Hubble constant, the rate in which the universe is expanding. The problem is that these numbers still differ significantly from the expansion rate determined by the observations of the cosmic microwave background by the Planck space telescope.

Hubble and Webb come up with a rate of expansion 73 km/s/Mpc, while Planck found an expansion rate of 67 km/s/Mpc. Though this difference appears small, the scientists in both groups claim their margin of error is much smaller than that difference, which means both can’t be right.

You can read the paper for these new results here.

The bottom line mystery remains: The data is clearly telling us one of two things: 1) the many assumptions that go into these numbers might be incorrect, explaining the difference, or 2) there is something fundamentally wrong about the Big Bang theory that cosmologists have been promoting for more than a half century as the only explanation for the formation of the universe.

The solution could also be a combination of both. Our data and our theories are wrong.

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Is this really a spiral galaxy?

10:16 am

Is this really a spiral galaxy?

The uncertainty of science: The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope and released on March 4, 2024 by the PR department of the European Space Agency (ESA) as part of its Hubble Picture of the Week program. It shows what the press release claims is a spiral galaxy about 55 million light years away, seen edge on.

In this image NGC 4423 appears to have quite an irregular, tubular form, so it might be surprising to find out that it is in fact a spiral galaxy. Knowing this, we can make out the denser central bulge of the galaxy, and the less crowded surrounding disc (the part that comprises the spiral arms).

If NGC 4423 were viewed face-on it would resemble the shape that we most associate with spiral galaxies: the spectacular curving arms sweeping out from a bright centre, interspersed with dimmer, darker, less populated regions. But when observing the skies we are constrained by the relative alignments between Earth and the objects that we are observing: we cannot simply reposition Earth so that we can get a better face-on view of NGC 4423!

This picture provides a great example of the amount of assumptions that are often contained in astronomical observations. Though the data strongly suggests this is spiral, we must remember this is merely an educated guess, based on that central bulge and the dust lanes visible along the galaxy’s profile. There is actually no guarantee that this is so. As the press release also notes, astronomers are constrained by our viewpoint, and cannot change that viewpoint to get a better view to confirm this guess. For all we know, a face on veiw of this flat galaxy would reveal it has no spiral arms, but instead is mottled and chaotic, a rare type that does exist.

Astronomers do the best they can, but it is important that they (and we) always recognize the limitations.

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Astronomers discover new moons around Neptune and Uranus

8:50 am

Using a observations over several years from a number of ground-based telescopes, astronomers have now identified two new moons around Neptune and one new moon circling Uranus.

The new Uranian member brings the ice giant planet’s total moon count to 28. At only 8 kilometers, it is probably the smallest of Uranus’ moons. It takes 680 days to orbit the planet. Provisionally named S/2023 U1, the new moon will eventually be named after a character from a Shakespeare play, in keeping with the naming conventions for outer Uranian satellites.

…The brighter Neptune moon now has a provisional designation S/2002 N5, is about 23 kilometers in size, and takes almost 9 years to orbit the ice giant. The fainter Neptune moon has a provisional designation S/2021 N1 and is about 14 kilometers with an orbit of almost 27 years. They will both receive permanent names based on the 50 Nereid sea goddesses in Greek mythology.

The two new Neptune moons raises its moon total now to sixteen. The orbits of all three are tilted and eccentric and far from the planets, strongly suggested they are capture asteroids, not objects formed at the same time as the planet.

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National Science Foundation decides to fund only one giant telescope

8:56 am

The National Science Foundation (NSF) has decided that its astronomy program does not have sufficient funds for building both the Thirty Meter Telescope (TMT) in Hawaii and the Giant Magellan Telescope (GMT) in Chile, and will decide in May which one it will choose.

The GMT and TMT—both backed by consortia of universities, philanthropic foundations, and international partners—set out to build their next generation instruments in the early 2000s. But this privately funded approach, which during the 20th century produced the twin 10-meter Keck telescopes in Hawaii and the two 6.5-meter Magellan telescopes in Chile, stumbled when it came to multibillion-dollar projects. Although design work and mirror casting forged ahead, both projects failed to amass enough funding to complete construction. (A dispute with Native Hawaiians over the Hawaii site has also slowed the TMT.)

I predict that this decision puts the final nail in TMT’s coffin. That telescope was on schedule in 2015 — when construction was set to begin — to be already operational now, well ahead of GMT. The opposition in Hawaii by a minority of leftist protestors, who also had the backing of the state government (run entirely by the Democratic Party), blocked that construction even as the building of GMT’s mirrors proceeded.

Almost a decade later, while TMT sits in limbo, unbuilt, GMT is nearing completion, with its last mirror presently being fabricated and construction at its site now more than half done. It is expected to be finished by 2028, and is almost certainly going to get that NSF funding.

As I noted however in July 2023,

Not that any of this really matters. In the near term, ground-based astronomy on Earth is going to become increasingly impractical and insufficient, first because of the difficulties of making good observations though the atmosphere and the tens of thousands of satellites expected in the coming decades, and second because new space-based astronomy is going to make it all obsolete. All it will take will be to launch one 8-meter telescope on Starship and [GMT] will become the equivalent of a buggy whip.

The great tragedy of TMT is that the astronomers themselves at the project were not willing to fight that tiny minority of protesters, whose protests were based on the essentials of critical race theory that makes whites the devils and all other minorities saints. As academics trained in these insane ideas, the astronomy community accepted this bigoted premise, and out of guilt allowed those protesters to rule.

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The coming April 8, 2024 total eclipse

12:09 pm

The next eclipses to cross the U.S.
Map by Michael Zeiler (GreatAmericanEclipse.com). Click for original.

On April 8, 2024 a large swath of the United States, from Texas to Maine, will have the opportunity to witness personally a total eclipse of the Sun by the Moon.

If you have never experienced a total eclipse, then you must do whatever you can to see this event, since the next eclipse within the United States will not happen again until 2044. Diane and I made a special trip to Idaho Falls, Idaho in 2017 to see that eclipse, and without doubt it was an experience that is difficult to describe. As I wrote afterward:

Totality was amazing. I was amazed by two things. First, how quiet it became. There were about hundred people scattered about the hotel lawn, with dogs and kids playing around. The hotel manager’s husband set up speakers for music and to make announcements, but when totality arrived he played nothing. People stopped talking. A hush fell over everything. Moreover, I think we somehow imagine a subconscious roar from the full sun. Covered as it was, with its soft corona gleaming gently around it, it suddenly seemed still.

Secondly, the amazing unlikeliness of the Moon being at just the right distance and size to periodically cause this event seemed almost miraculous. Watching it happen drove this point home to me. And since eclipses themselves have been a critical event in the intellectual development of humanity, helping to drive learning and our understanding of the universe, it truly makes me wonder at the majesty of it. I do not believe in any particular religion or their rituals (though I consider the Bible, the Old Testament especially, to be a very good manual for creating a good life and society), but I do not deny the existence of a higher power. Something made this place, and set it up in this wonderous way. Today’s eclipse only served to demonstrate this fact to me again.

» Read more

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NASA high altitude science balloon sets new endurance record

9:57 am

GUSTO's flight path
Click for continuous tracking of GUSTO’s flight path

NASA’s GUSTO high altitude science balloon has now set a new endurance record for the most days of flight of a NASA balloon, flying more than 57 days over the continent of Antarctica at the south pole.

The map to the right shows GUSTO’s entire journey. The blue line was its first phrase of travel, the green its second phase, and the red its present stage.

GUSTO was launched at 1:30 a.m. EST Dec. 31 from the Long Duration Balloon Camp near McMurdo Station, Antarctica. The balloon mission not only broke the flight record but continues its path circumnavigating the South Pole. The stadium-sized zero-pressure scientific balloon and observatory are currently reaching altitudes above 125,000 feet. “The health of the balloon and the stratospheric winds are both contributing to the success of the mission so far,” said Hamilton. “The balloon and balloon systems have been performing beautifully, and we’re seeing no degradation in the performance of the balloon. The winds in the stratosphere have been very favorable and have provided stable conditions for extended flight.”

The previous NASA record was a balloon that it flew in 2012. GUSTO itself is being used to map the Milky Way’s carbon, oxygen, and nitrogen that is found between the stars in gas clouds.

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Webb: Infrared data sees neutron star remaining after 1987 supernova, the nearest in more than 4 centuries

9:29 am

Webb's infrared view of Supernova 1987a
Click for original image.

Using the Webb Space Telescope, astronomers have obtained infrared data that confirms the existence of a neutron star at the location of Supernova 1987a, located in the Large Magellanic Cloud, the nearest such supernova in more than four centuries and the only one visible to the naked eye since the invention of the telescope.

Indirect evidence for the presence of a neutron star at the center of the remnant has been found in the past few years, and observations of much older supernova remnants — such as the Crab Nebula — confirm that neutron stars are found in many supernova remnants. However, no direct evidence of a neutron star in the aftermath of SN 1987A (or any other such recent supernova explosion) had been observed, until now.

…Spectral analysis of the [Webb] results showed a strong signal due to ionized argon from the center of the ejected material that surrounds the original site of SN 1987A. Subsequent observations using Webb’s NIRSpec (Near-Infrared Spectrograph) IFU at shorter wavelengths found even more heavily ionized chemical elements, particularly five times ionized argon (meaning argon atoms that have lost five of their 18 electrons). Such ions require highly energetic photons to form, and those photons have to come from somewhere.

That “somewhere” has to be a neutron star, based on present theories. The image above shows three different Webb views of Supernova 1987a, with the one on the lower right suggesting the existence of a point source at the center of the supernova remnant. In the left image the circular ring of bright spots is an older ring of dust and material that has been lit up by the crash of the explosive material (as indicated in blue at the center) flung out from the star when it went supernova and collapsed into a neutron star. That wave of explosive material took several decades to reach the ring and enflame it.

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Astronomers: a 9,000-light-year-long stream of gas and dust ripples like a wave due to the Milky Way’s gravity

11:24 am

According to an analysis of data from the space telescope Gaia, astronomers now believe that a 9,000-light- year-long stream of gas and dust that is only 500 light years away from the Sun at its nearest point ripples up and down like a wave, due to the Milky Way’s gravity.

Dubbed the Radcliffe Wave after the institute in which the astronomers were based who first discovered it, the scientists determined its wavelike behavior by mapping the motions of the star clusters along its length. Apparently, over time they are moving up and down, not unlike fans at a stadium doing the wave.

The data also includes these intriguing results:

“It turns out that no significant dark matter is needed to explain the motion we observe,” Konietzka said. “The gravity of ordinary matter alone is enough to drive the waving of the Wave.”

In addition, the discovery of the oscillation raises new questions about the preponderance of these waves both across the Milky Way and other galaxies. Since the Radcliffe Wave appears to form the backbone of the nearest spiral arm in the Milky Way, the waving of the Wave could imply that spiral arms of galaxies oscillate in general, making galaxies even more dynamic than previously thought. “The question is, what caused the displacement giving rise to the waving we see?,” Goodman said. “And does it happen all over the galaxy? In all galaxies? Does it happen occasionally? Does it happen all the time?”

That no dark matter is involved causes a lot of problems for the hypothesis that such material exists, causing the motions of stars in the outer regions all galaxies to orbit the galaxy faster than they should. Why would dark matter cause that increased rotation, but have no impact on this wave? It is a paradox that is not easily resolved.

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Orbital perturbations caused by passing stars might very well have caused past extinctions

11:21 am

According to new computer simulations, scientists now think that any calculations of the long term changes in the orbits of the planets in our solar system must include the orbital perturbations caused by passing stars, perturbations that might very well have caused past extinctions. From their paper’s introduction:

Simulations of the long-term orbital evolution of the Sun’s planets have nearly always modeled the solar system as an isolated system. For many purposes, this is a very good approximation, but the solar system is of course part of the Milky Way Galaxy. Consequently, it occasionally suffers close encounters with other field stars, and solar neighborhood kinematic studies predict an average of ∼20 stellar passages within 1 [parsec] of the Sun each [million years].

Because the solar system cross section scales with the square of heliocentric distance, the large majority of these encounters will be distant and inconsequential to the planets’ dynamics, but this is not guaranteed. In fact, there is a ∼0.5% chance that a field star passage will trigger the loss of one or more planets over the next 5 [billion years], and such passages may actually guarantee the disruption of the planets’ orbits many [billion years] after the Sun becomes a white dwarf. Yet, encounters need not trigger an instability for them to have dynamical consequences for the planets. For instance, it has been suggested that ∼one-third of Neptune’s modern eccentricity has been generated through past stellar encounters, but many of the long-term dynamical effects of stellar passages remain unknown.

Their simulations as well as other data suggest that for computer models to have any chance of accurately calculating the orbital evolution of the solar system’s planets, those models must include the passing of nearby stars.

Or to put it in more blunt terms, the uncertainties here are so great that it is unlikely any computer model will ever be able to reconstruct our solar system going back further than 50 million years.

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A galaxy with a tail of star-forming clusters

10:34 am

A galaxy with a tail of newborn stars
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Cool image time! The picture to the right, reduced and sharpened to post here, was taken by the Hubble Space Telescope as part of a survey of twelve different galaxies that have long tails. In this case, the galaxy is named Arp-Madore 1054-325, and the tail that trails off in the upper left is caused by the gravity of the nearby neighboring galaxy, which I think is the patch of stars just below it. Within it are many star clusters where new stars are forming. From the caption:

A team of astronomers used a combination of new observations and archival data to get ages and masses of tidal tail star clusters. They found that these clusters are very young — only 10 million years old. And they seem to be forming at the same rate along tails stretching for thousands of light-years. “It’s a surprise to see lots of the young objects in the tails. It tells us a lot about cluster formation efficiency,” said lead author Michael Rodruck of Randolph-Macon College in Ashland, Virginia.

Before the mergers, the galaxies were rich in dusty clouds of molecular hydrogen that may have simply remained inert. But the clouds got jostled and bumped into each other during the encounters. This compressed the hydrogen to the point where it precipitated a firestorm of star birth.

In some ways this galaxy portends one possible future of the Milky Way, after it collides with the nearby Andromeda galaxy in the far future.

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A soft but dim spiral

10:51 am

A soft but dim spiral
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Cool image time! The picture to the right, cropped, reduced, and sharpened to post here, was taken by the Hubble Space Telescope as part of a survey of nearby galaxies in which supernovae had previously been detected.

This softly luminous galaxy — lying in the constellation Hercules, about 110 million light-years from Earth — seems outshone by the sparkling foreground stars that surround it. The type II supernova which took place in this galaxy in 2019, while no longer visible in this image, definitely outshone the galaxy at the time!

What amazes me about this somewhat dim spiral galaxy is its beautiful structure, its two spiral arms coiling outward in perfect symmetry. And yet, we are looking at a object that is almost entirely empty space, hundreds of thousands of light years across. Somehow the almost infinitesimal force of gravity at those distances is still able to shape the arms, and the spirals.

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Another exoplanet found in habitable zone

9:55 am

Astronomers using both space- and ground-based telescopes have confirmed the existence of another rocky exoplanet inside the habitable zone of its star.

The star is a red dwarf 137 light years away. The exoplanet, dubbed TOI-175 b, is estimated to be larger than Earth, with a diameter 1.5 times that of our home planet. It orbits its star every nineteen days. Even more intriguing, the data suggests this star has a second exoplanet even better positioned in the habitable zone that would be the smallest habitable-zone exoplanet so far found, about the size of Earth.

The second planet however is not yet confirmed.

This discovery is no longer very unique. In the past few years astronomers have discovered a plethora of Earth-sized exoplanets, many in the habitable zone.

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The dark matter in the Milky Way is not behaving as its supposed to

8:56 am

The uncertainty of science: Scientists using precise data of the motions of the outer stars of the Milky Way from the Gaia orbiting telescope have found they do not rotate the galaxy’s center as fast as expected, based on the theory of the existence of dark matter.

Dark matter was proposed to explain why in other galaxies the speed of rotation of outer stars does not appear to decline with distance (as seen for example with the planets in our solar system) but remains the same, no matter how far out you go. That extra speed suggests there must be unseen matter pulling on the stars.

[N]ew results that combine Gaia measurements with those from APOGEE (Apache Point Observatory Galactic Evolution Experiment), performed on a ground-based telescope in New Mexico, USA, and which measures the physical properties of stars to better judge their distance, have indeed measured the Milky Way’s rotation curve for stars out farther than ever before, to about 100,000 light years. “What we were really surprised to see was that this curve remained flat, flat, flat out to a certain distance, and then it started tanking,” says Lina Necib, who is an assistant professor of physics at MIT, said in a statement. “This means the outer stars are rotating a little slower than expected, which is a very surprising result.”

…The decline in orbital velocity at these distances implies that there is less dark matter in the center of our galaxy than expected. The research team describe the galaxy’s halo of dark matter as having been “cored,” somewhat like an apple. The crew also says there’s not enough gravity from what dark matter there seems to exist there, to reach all the way out to 100,000 light years and keep stars moving at the same velocity.

The rotation data of other galaxies, while somewhat robust, also includes a number of assumptions might be fooling us into thinking that the speeds are higher than expected. The more precise data gathered nearby, in the Milky Way, is now suggesting those assumptions and that distant data must be questioned.

Or to put it more bluntly, dark matter remains an ad hoc solution to a mystery that astronomers really don’t understand, or have sufficient data to explain. It might very well be a wild goose chase that has made them miss the real answer, whatever that might be.

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