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Instead of relying on energy-hungry reactors to generate high temperatures and pressure, researchers are looking underground at Earth's natural heat and forces to cook up ammonia for fertilizer. In a proof-of-concept study, researchers generated ammonia by mixing nitrogen-laced water with iron-rich rocks -- without any energy input or CO2 emission. This new recipe may lead to a more sustainable alternative to current methods, theoretically churning out enough ammonia for 2.42 million years.

Researchers present paper-based temperature and humidity sensors that are accurate, reliable, and eco-friendly. The team created the sensors by printing silver lines on commercially available paper through dry additive nanomanufacturing. As the paper absorbs water vapor, its capacitance change is measured to reflect the relative humidity of the environment, and as the temperature increases, the metallic conductor experiences an increase in resistivity. They successfully detected changes in relative humidity levels from 20% to 90% and temperature variations from 25 C to 50 C.

The megaflood that refilled the Mediterranean Sea 5 million years ago was so huge and fast that it shaped the landscape of what is now Sicily

From carefully timing meals and bedtime to turning down the lights and banning screens in bed, here's what the scientists who study sleep do to optimise their slumber

The ISS’s orbit is slowly decaying. While it might seem a permanent fixture in the sky, the orbiting space laboratory is only about 400 km above the planet. There might not be a lot of atmosphere at that altitude. However, there is still some, and interacting with that is gradually slowing the orbital speed of the station, decreasing its orbit, and, eventually, pulling it back to Earth. That is, if we didn’t do anything to stop it. Over the 25-year lifespan of the station, hundreds of tons of hydrazine rocket fuel have been carried to it to enable rocket-propelled orbital maneuvers to keep its orbit from decaying. But what if there was a better way – one that was self-powered, inexpensive, and didn’t require constant refueling?

A new paper from Giovanni Anese, a PhD student at the University of Padua, and his team focuses on such a concept. It uses a new idea called a Bare Photovoltaic Tether (BPT), which is based on an older idea of an electrodynamic tether (EDT) but has some advantages due to the addition of solar panels along its length.

The basic idea behind a BPT, and EDTs more generally, is to extend a conductive boom out into a magnetic field and use the natural magnetic forces in the environment to provide a propulsive force. Essentially, it deploys a giant conductive rod into a magnetic field and uses the force on an electric field created in that rod to transfer force to where the rod is connected. It’s like the wind picking up an umbrella if the umbrella were a massive conductive rod and the wind were the planet’s natural magnetic field.

Fraser interviews Rob Hoyt from Tethers Unlimited, one of the companies offering commercial EDTs for satellites.

Electrodynamic tethers are not a new concept. They were initially introduced in 1968 by Giuseppe Colombo and Mario Grossi at Harvard’s Center for Astrophysics. Several demonstration missions have already taken flight, such as the TSS-1R that launched on the Space Shuttle Atlantis in 1996 and successfully deployed a 10-km long tether from the shuttle. Another experiment called the Plasma Motor Generator took place on the Russian space station Mir in 1999, which, instead of using an electromotive force to prove orbital stationkeeping, generated power directly from the tether itself.

Engineers have long considered using an EDT to perform stationkeeping duties on the ISS. However, a technical quirk made it impractical. To get the right sort of forces, the tether would need to be pointed “downward” toward the Earth or “upward” away from the planet.

No matter the direction in which the tether is pointed, it will still require power to operate. Without its magnetic field, caused by the electrical current running through it, it would act as a further drag rather than a boost. Therefore, a traditional EDT must be tied to a power system. However, if an EDT is deployed upward on the ISS, this power system would inhibit the approach corridors of capsules attempting to dock with the station. 

MiTEE is a concept mission from the University of Michigan utilizing Electrodynamic tethers.

This necessitates a downward-facing EDT so it can be connected to the ISS’s power system. While that does work, according to a prior paper published by the authors, it is less than ideal as downward-facing tethers are typically used in de-orbiting maneuvers rather than orbit-boosting ones. 

Enter the BPT. The main difference between it and a traditional EDT is that its surface is at least partially covered in solar panels. If there are enough of them, these solar panels can completely power the system, allowing an upward-facing BPT to operate without being tied into the ISS’s power grid and keeping the approach lanes clear for arriving spacecraft. 

Mr. Anese and his team studied different options in terms of length and solar panel coverage, disregarding the tether’s weight, as the difference in weight between the tether and the ISS itself was several orders of magnitude. They found that they could counteract the relatively small force that causes a 2km/month orbital drop from the ISS by utilizing a 15 km long tether around 97% covered in solar panels, at least on one side.

Fraser discusses orbital station-keeping for the ISS with Michael Rodruck

A 15 km tether might sound absurdly long, and admittedly, if pointing back to the Earth, it would cover a relatively large percentage of the total distance back to the ground. However, it is well within the realm of technological feasibility, especially given that Atlantis deployed that 10 km tether almost 30 years ago.

To prove their point, the authors turned to a software package called FLEXSIM, which allowed them to simulate the orbital dynamics of an ISS attached to different lengths of BPT. The tethers they chose were only 2.5cm wide, and the solar panels were only 4.23% efficient, though that is likely affected by the fact they had to be small and flexible. With that length of solar panels, the system could provide 8.3 kW of power for the whole tether, enough to boost the ISS’s orbital path.

There are some nuances about the effects of solar activity on the forces contributing to the orbital boost, but overall, the system, at least in theory, does seem to work. However, much discussion around the ISS lately has been about its end of life, which could come as early as 2031. So, while there are still a few good years left in the station, it likely won’t benefit as much from the BPT system as it would have a few decades ago. That being said, there will likely be a replacement in orbit someday, and it could benefit from such a system from the outset, which could save hundreds of tons of fuel in orbit over its lifetime.

Learn More:
Anese et al – Bare Photovoltaic Tether characteristics for ISS reboost
UT – Satellites Equipped With a Tether Would be Able to De-Orbit Themselves at the end of Their Life
UT – A New Satellite Is Going to Try to Maintain Low Earth Orbit Without Any Propellant
UT – SpaceX Reveals the Beefed-Up Dragon That Will De-Orbit the ISS

Lead Image:
Force diagram of the BPT tether system on the ISS.
Credit – Anese et al.

The post A Tether Covered in Solar Panels Could Boost the ISS’s Orbit appeared first on Universe Today.

If you click on the link below, you’ll go to Trump’s executive order, signed in his first day in office, ending DEI positions in the government and describing the dismantling of DEI programs.

As readers know, I’m not a fan of Trump, whom I see as dangerously unstable, and I’m not a MAGA-ite. Regardless, neither will I damn everything his administration does as harmful or evil, for that’s simply not the case, and those determined to do that from the outset have a problem.  In this case, the action seems salubrious.

Here’s the whole thing; I’ve put in bold part that I see as especially important:

By the authority vested in me as President by the Constitution and the laws of the United States of America, it is hereby ordered:

Section 1.  Purpose and Policy.  The Biden Administration forced illegal and immoral discrimination programs, going by the name “diversity, equity, and inclusion” (DEI), into virtually all aspects of the Federal Government, in areas ranging from airline safety to the military.  This was a concerted effort stemming from President Biden’s first day in office, when he issued Executive Order 13985, “Advancing Racial Equity and Support for Underserved Communities Through the Federal Government.”

Pursuant to Executive Order 13985 and follow-on orders, nearly every Federal agency and entity submitted “Equity Action Plans” to detail the ways that they have furthered DEIs infiltration of the Federal Government.  The public release of these plans demonstrated immense public waste and shameful discrimination.  That ends today.  Americans deserve a government committed to serving every person with equal dignity and respect, and to expending precious taxpayer resources only on making America great.

Sec. 2.  Implementation.  (a)  The Director of the Office of Management and Budget (OMB), assisted by the Attorney General and the Director of the Office of Personnel Management (OPM), shall coordinate the termination of all discriminatory programs, including illegal DEI and “diversity, equity, inclusion, and accessibility” (DEIA) mandates, policies, programs, preferences, and activities in the Federal Government, under whatever name they appear.  To carry out this directive, the Director of OPM, with the assistance of the Attorney General as requested, shall review and revise, as appropriate, all existing Federal employment practices, union contracts, and training policies or programs to comply with this order.  Federal employment practices, including Federal employee performance reviews, shall reward individual initiative, skills, performance, and hard work and shall not under any circumstances consider DEI or DEIA factors, goals, policies, mandates, or requirements.

(b)  Each agency, department, or commission head, in consultation with the Attorney General, the Director of OMB, and the Director of OPM, as appropriate, shall take the following actions within sixty days of this order:

(i)    terminate, to the maximum extent allowed by law, all DEI, DEIA, and “environmental justice” offices and positions (including but not limited to “Chief Diversity Officer” positions); all “equity action plans,” “equity” actions, initiatives, or programs, “equity-related” grants or contracts; and all DEI or DEIA performance requirements for employees, contractors, or grantees.

(ii)   provide the Director of the OMB with a list of all:

(A)  agency or department DEI, DEIA, or “environmental justice” positions, committees, programs, services, activities, budgets, and expenditures in existence on November 4, 2024, and an assessment of whether these positions, committees, programs, services, activities, budgets, and expenditures have been misleadingly relabeled in an attempt to preserve their pre-November 4, 2024 function;

(B)  Federal contractors who have provided DEI training or DEI training materials to agency or department employees; and

(C)  Federal grantees who received Federal funding to provide or advance DEI, DEIA, or “environmental justice” programs, services, or activities since January 20, 2021.

(iii)  direct the deputy agency or department head to:

(A) assess the operational impact (e.g., the number of new DEI hires) and cost of the prior administration’s DEI, DEIA, and “environmental justice” programs and policies; and

(B) recommend actions, such as Congressional notifications under 28 U.S.C. 530D, to align agency or department programs, activities, policies, regulations, guidance, employment practices, enforcement activities, contracts (including set-asides), grants, consent orders, and litigating positions with the policy of equal dignity and respect identified in section 1 of this order.  The agency or department head and the Director of OMB shall jointly ensure that the deputy agency or department head has the authority and resources needed to carry out this directive.

(c)  To inform and advise the President, so that he may formulate appropriate and effective civil-rights policies for the Executive Branch, the Assistant to the President for Domestic Policy shall convene a monthly meeting attended by the Director of OMB, the Director of OPM, and each deputy agency or department head to:

(i)    hear reports on the prevalence and the economic and social costs of DEI, DEIA, and “environmental justice” in agency or department programs, activities, policies, regulations, guidance, employment practices, enforcement activities, contracts (including set-asides), grants, consent orders, and litigating positions;

(ii)   discuss any barriers to measures to comply with this order; and

(iii)  monitor and track agency and department progress and identify potential areas for additional Presidential or legislative action to advance the policy of equal dignity and respect.

Sec. 3.  Severability.  If any provision of this order, or the application of any provision to any person or circumstance, is held to be invalid, the remainder of this order and the application of its provisions to any other persons or circumstances shall not be affected.

Sec. 4.  General Provisions.  (a)  Nothing in this order shall be construed to impair or otherwise affect:

(i)   the authority granted by law to an executive department or agency, or the head thereof; or

(ii)  the functions of the Director of the Office of Management and Budget relating to budgetary, administrative, or legislative proposals.

(b)  This order shall be implemented consistent with applicable law and subject to the availability of appropriations.

(c)  This order is not intended to, and does not, create any right or benefit, substantive or procedural, enforceable at law or in equity by any party against the United States, its departments, agencies, or entities, its officers, employees, or agents, or any other person.

THE WHITE HOUSE,

January 20, 2025.

Although I feel that the government (and its citizens) need to give people in the underclass a hand up, I think in general that has to be through the creation of a system of equal opportunities from birth rather than equal representation in colleges and hiring (“equity”). Inequities are often imputed to structural racism acting right now, but, at least in academia, that doesn’t seem to be the case. If racism or misogyny is a cause, it was bigotry in the past whose effects persist in the present, reducing equal opportunity. While it’s a lot harder to effect equal opportunity, as that means effacing the environmental differences that, say, hold back black and Hispanic children from accessing good educations and decent resources.  Rectifying this also involve effacing cultural differences, for example the attitude that I’ve seen that smart minority kids, and those who study hard, are somehow  “acting white”—something to be denigrated.  Fixing this entails a herculean task which will cost money (even worse, creating cultural changes, for we know that simply throwing more money at schools doesn’t improve education).  But it’s the only way to help those who, for no fault of their own, lack opportunity.

That said, the solution is not DEI programs, which have not done anything to equalize opportunity, and have effaced the idea of merit, replacing it with identity. By the time DEI programs kick in, usually in or after college or in hiring after high school, it’s too late. Further, it’s widely recognized that DEI training does not change people’s attitudes.

Finally, there is a sense of palpable unfairness with aspects of DEI that are racist in the sense that people are advanced at high levels because of their ancestry.  One example in science are grants that are either given out preferentially to investigators from minority groups or, especially, grants given out with DEI aims: grants designed to show that structural racism is responsible for inequities X, Y, and Z. (See this post on how National Science Foundation grants studying DEI issues have gone from 0.29% of all grants in 2021 ($14,280,928) to 27.21% of all grants ($289,593,584) in 2024. All scientists are aware of this, and of the paucity of anything useful coming from such funding.

Under the new order, not only will all DEI positions and programs be terminated in the government, including jobs relabeled to hide the fact that they were DEI positions. As section ii(E) suggests, this would also include federal grant money used to further equity, which presumably means federal grants to science.

These are early days, and it’s not clear to me whether public universities or schools with DEI programs will have to terminate them or surrender government funding, but if that’s the case, places like the University of Michigan are going to lose a lot of jobs.

And it looks as if the requirement of including DEI statements for job applications is on its way down the drain. That is good because I consider this compulsory speech that is prima facie illegal, though almost nobody’s challenged this in court.

You heard it here first, folks, so the New Yorker was slow on the uptake (and they don’t have the photos and videos that I featured). At any rate, the new issue features the recent story of Robert Lang, master origami artist and reader, whose wildlife photographs have been featured here often (and there are more to come).  If you don’t have a subscription, you can click on the NYer headline below and read the piece perhaps once, but otherwise I’ll give some excerpts from the story and add that a judicious inquiry might yield a pdf.

First, though, have a look at Robert’s origami page to see the incredible art he’s made. (I’ll wager he’s one of the ten best origami artists in the world.) As he told me, he lost virtually all of the art he had kept during the fire, which burned up his and his wife’s old home and studio, as well as a new home down the block. They have insurance and will rebuild.  In the meantime, I told him that I still had an origami duck he folded for me, and he responded that it was probably one of the few surviving original Langs.  It sits atop my computer, and here it is (it is another version of his “Duck Opus 11” on watercolor paper that you can see here).

And the story:

Here are some excerpts:

“The first thing you think of when you see your home engulfed in flames is, My world and future have changed,” Robert J. Lang, one of the world’s foremost origami artists and theorists, said recently. He was sitting in a small hotel room in Arcadia, California. The week prior, the house where he lived with his wife, Diane, had burned down when the Eaton Fire erupted and swept through Altadena, outside Los Angeles, with incredible speed, levelling entire neighborhoods. Robert’s studio, a separate property where he kept decades of his professional origami work—all highly flammable— along with research and personal artifacts, was also reduced to ash.

Diane walked in with their two dogs, Casey and Scout, who hopped onto the mattress and lay down. Diane, with no other place to sit in the room, joined them. “Two people offered their back yards for them to wander around in,” she said. “So, we were just in a back yard.”

The Langs had gone to sleep on a Monday night in their own bed. By Tuesday night, they were sleeping in their cars, with their many pets—the two dogs, two desert tortoises (Sal and Rhody), a Russian tortoise (Ivan), a snake (Sandy), and a tarantula (Nicki)—and the few things they could grab as they fled the inferno. The snake, tortoises, and tarantula were now being taken care of at the San Dimas Canyon Nature Center, rather than staying at the hotel. “Just to make my life simpler,” Diane, who works with the Eaton Canyon Nature Center, said.

In the early hours of Wednesday morning, Robert watched his studio burn from a nearby ridge. Then, at around 9 A.M., he and Diane learned that their home was destroyed. At sixty-three years old, Robert, who was profiled in this magazine in 2007, has been designing origami for most of his life; one of his early designs, in the seventies, was an origami Jimmy Carter. He used to be a physicist, working on things like semiconductor lasers, at places such as NASA’s Jet Propulsion Lab, before he decided to devote his time fully to origami. The studio held much of his art, and all of his tools. The laser cutter he used to help make prototypes had melted. “It’s now a pile of metal,” he said. “A 3-D printer is now a pile of ash.” Rare paper, including fig-based paper from a tiny village in Mexico, had burned. He went on, “There were correspondence letters with other origami artists over the years that were a historical record for me and perhaps for others. And then my exhibition collection was there. The pieces I had in MoMA”—a large grizzly bear, a bull moose, and a fiddler crab, all folded between 2003 and 2007—“are gone.” As he evacuated, however, he was able to grab a single piece of art work, perhaps his most famous: a framed, fifteen-inch cuckoo clock folded into dazzling complexity from a single sheet of paper

. . . .Most of the Langs’ days now are spent on details. Dealing with insurance. Filing documents of everything lost. Texting with neighbors. Walking the dogs. Checking the weather for changes in wind. Monitoring evacuation zone updates from the Watch Duty app. And, mainly, finding a more stable place to live.

Robert’s phone rang. Their real-estate agent had a prospective rental apartment they could see that afternoon.

“Ask him about the dogs,” Diane said to Robert. She explained, “We’d founda place we liked—a good vibe. But the owner said he didn’t want dogs.”

Robert hung up. “They take dogs,” he said. “We can see it at 3 P.M.”

“It’ll probably be for two years,” Diane said. “But we’ll rebuild. We still have our land. We even have the floor plans.”

And they will rebuild on the site of their new home and of their original studio. It may take a couple of years, but, as I said in my previous post, the Langs are remarkably resilient and are just getting on with what they need to do.

As for the cuckoo clock he saved: here it is, reproduced with permission. You can see it and read about it here, but he adds:

This is the one I saved.  There are four of them in existence (that I folded; lots of other people have followed the folding instructions to make their own versions). One of them was also in a fire that destroyed the owners’ apartment, but almost miraculously, it survived. He had a fourth-floor apartment in a building in which all the interior collapsed in the fire. After the fire, he was poking through the rubble in the basement, lifted a collapsed door that he recognized as his, and found the cuckoo clock, flattened, but unburnt. He sent it to me, and I spent some time restoring it (dampening, wiping off the ash that caked it, and re-folding/re-shaping it). I eventually got it back to its original appearance, though it still had bits of ash in crevices and smelled of smoke, but that just added to its character, and to my knowledge, it survives to this day.]

Here’s the first time I met Robert—at the Kent Presents meeting in Connecticut in August, 2018. (There’s a description here; sadly I’ve removed all photos from this site before January of last year because of copyright claims by stupid and venal firms, but there is a video of some origami that I’ve put below.) This photo shows part of Robert’s presentation, which was accompanied by slides of his artwork). Here Lang (left) talks to biology Nobel laureate Harold Varmus:

Here’s the video showing some of Robert’s origami:

It is possible to speed up how quickly you get over jet lag – but calculating the right way to do it based on flight times, time zones and light exposure can be tricky

James Temple was "in the right place at the right time" to take these dramatic images of SpaceX's Starship's seventh flight test disintegrating above the Atlantic Ocean

Observations of WASP-127b, a giant gas exoplanet more than 500 light years from Earth, suggest it has phenomenally high wind speeds

Adding rows of upright panels on farmland generates green power in the morning and evening while acting as a windbreak for crops

If you've missed out on sleep, it is possible to catch up. But is it better to try to do it all in one go or spread out over time – and is it really so bad to sleep in at the weekend?

I’m at that age, 67 going in 68, where it is reasonable to yell at the clouds. Which, come to think of it, may be a good title for another collection of my SBM essays. Aging does indeed suck, but it is, usually, better than the alternative. As we, and by we I mean my family and me, age we get the […]

The post Old Doctor Yells At Clouds first appeared on Science-Based Medicine.

Physicists have created a 3D shape called the cosmohedron, which can be used to reconstruct the quantum wavefunction of the universe - and potentially do away with the idea of space-time as the underlying fabric of the universe

The newer the data, and the longer we've had to study the epidemiology, the less harm we find that Agent Orange caused.

Learn about your ad choices: dovetail.prx.org/ad-choices

After a close look with a powerful radio telescope, astronomers are still puzzled by a pair of objects with strange characteristics first spotted in 2021

What came first, galaxies or planets? The answer has always been galaxies, but new research is changing that idea.

Could habitable planets really have formed before there were galaxies?

In the immediate aftermath of the Big Bang, there were no heavy elements. There was only hydrogen, which comprised about 75% of the mass, and helium, which comprised the remaining 25%. (There were probably also trace amounts of lithium, even beryllium.) There was nothing heavier, meaning there was nothing for rocky planets to form from. After a few hundred million years, the first stars and galaxies formed.

As successive generations of stars lived and died, they forged heavier elements and spread them out into the Universe. Only after that could rocky planets form, and by extension, habitable planets. That’s been axiomatic in astronomy.

However, new research that’s yet to be published suggests that habitable worlds could’ve formed in the early stages of the Cosmic Dawn, prior to galaxies forming. Its title is “Habitable Worlds Formed at Cosmic Dawn,” and it’s available at the pre-press site arxiv.org. The lead author is Daniel Whalen from the Institute of Cosmology and Gravitation at the University of Portsmouth in the UK.

The research hinges on primordial supernovae, the first stars in the Universe to explode. These massive stars lived fast and died young in cataclysmic explosions. They peaked at about redshift 20 when population III stars, which were extremely massive, exploded as pair-instability supernovae. Simulations show that these stars formed in dark matter haloes where the temperature allowed large amounts of molecular hydrogen to gather.

According to Whalen and his co-researchers, when these stars exploded, low-mass stars formed in the aftermath. Planetesimals formed around those stars, leading to the formation of potentially habitable, rocky worlds. This all happened before the first galaxies formed. These results are based on simulations the research team performed with Enzo.

It starts with a star forming with about 200 solar masses. It lives for only about 2.6 million years before it explodes as a PI supernova. The explosion enriches the supernova bubble to high metallicity. In the aftermath, hydrostatic instabilities cause a dense core to form about 3 million years later, with 35 solar masses.

“All known prerequisites for planet formation in this core are fulfilled: dust growth, dust enhancement in a dead zone, the onset of the streaming instability, and conversion of dust to planetesimals,” the authors explain.

This figure from the research shows a PI supernova exploding (a) and a dense core forming (b) about 3 million years later containing 35 solar masses. Image Credit: Whalen et al. 2025.

Here’s where this study differs from previous ones. Since the PI supernova explodes and creates high-metallicity gas, the gas cools more quickly. That allows the next star to form sooner, and hence, planetesimals and planets.

Eventually, a protostar with 0.3 solar masses formed. Then planetesimals formed between 0.46 and 1.66 AU from their star. Life needs water, and the researchers’ simulations also showed that the young solar system contained an amount of water similar to our own Solar System.

This figure from the research shows the protoplanetary disk. Gas, dust and planetesimal distributions are shown 39 kyr after the formation of the protostar in (a) – (c), respectively, where b and c show the central 4 AU of the disk. The green dashed circles indicate where water can exist in liquid form. Image Credit: Whalen et al. 2025.

Planetesimals formed in the circumstellar disk around the low-mass star, and over time, they combined to form planets. Since the original primordial supernovae created elements like carbon, oxygen, and iron, all of the necessary ingredients were likely present to form rocky planets, even life.

The remarkable part is that this could’ve happened before the first galaxies formed. If true, it would change our understanding of the Universe and of life. However, this is just one simulation. How could observations support it?

“These planets could be detected as extinct worlds around ancient, metal-poor stars in the Galaxy in future exoplanet surveys,” Whelan and his fellow researchers write in their paper.

According to the authors, if conditions were just right, rocky planets could have formed even earlier than their simulations show. If that’s true, then it changes the entire course of events in the evolution of the Universe.

However, this is only a single study. And it hinges on primordial supernovae. Did they even exist? There’s at least some evidence that they did.

Clearly, attempting to observe primordial supernovae is extremely difficult. They occurred so long ago that they’re extraordinarily distant and faint. It’s likely impossible with current technology.

Also, there is much uncertainty about the Population III stars that were the progenitors of primordial supernovae. Their exact masses, lifetimes, and explosion mechanisms are uncertain. Astronomers don’t have a clear understanding of the early Universe’s extreme conditions. It’s still evolving, as is our understanding of supernovae. Combined, that’s a lot of uncertainty.

An artist’s illustration of some of the Universe’s first stars. Called Population 3 stars, they formed a few hundred million years after the Big Bang. Image Credit: By NASA/WMAP Science Team – https://www.nasa.gov/vision/universe/starsgalaxies/fuse_fossil_galaxies.html (image link), Public Domain, https://commons.wikimedia.org/w/index.php?curid=1582286

Still, all of these challenges don’t mean that primordial supernovae didn’t exist. So astronomers can’t rule them out, nor can they rule out very early habitable planets.

As things stand, there’s no way to prove or disprove this research. However, it does open another line of thinking and new possibilities.

The post Habitable Worlds Could Have Formed Before the First Galaxies appeared first on Universe Today.

The Andromeda galaxy is our closest galactic neighbour, barring dwarf galaxies that are gravitationally bound to the Milky Way. When conditions are right, we can see it with the naked eye, though it appears as a grey smudge. It’s the furthest object in the Universe that we can see without telescopic help.

The Hubble Space Telescope has created a massive 2.5-gigapixel panorama of Andromeda. It took 10 years and more than 1,000 orbits to capture all of the images.

We’re stuck inside the Milky Way and will never escape it. (Yes, there’s a tiny possibility we will in some far-off future.) The ESA’s powerful Gaia telescope has given us our best look at our own galaxy from inside it, but even it has its limitations.

That’s one of the reasons that observing Andromeda, also known as M31, is important. Like the Milky Way, M31 is also a barred spiral. By observing M31 in detail, we can learn more about our own galaxy. M31 is like a proxy for the Milky Way, and astronomers’ chief tool for studying our galactic proxy is the Hubble.

“With Hubble we can get into enormous detail about what’s happening on a holistic scale across the entire disk of the galaxy. You can’t do that with any other large galaxy,” said principal investigator Ben Williams of the University of Washington.

The image is a mosaic comprising at least 2.5 billion pixels. It resolves about 200 million individual stars, all of them hotter than our Sun. That’s only a small fraction of the galaxy’s stellar population, as dim stars like red dwarfs aren’t detected. The image contains bright blue star clusters, background galaxies, foreground stars, satellite galaxies, and dust lanes.

This is the largest photomosaic ever made by the Hubble Space Telescope. Andromeda is seen almost edge-on, tilted by 77 degrees relative to Earth’s view. The galaxy is so large that the mosaic is assembled from approximately 600 separate fields of view taken over 10 years of Hubble observing. The Andromeda galaxy is shown at the top of the visual. It is a spiral galaxy that spreads across the image. It is tilted nearly edge-on to our line of sight so that it appears very oval. The borders of the galaxy are jagged because the image is a mosaic of smaller, square images against a black background. The outer edges of the galaxy are blue, while the inner two-thirds are yellowish with a bright, central core. Five callout squares highlight interesting features of the galaxy. Image Credit: NASA, ESA, B. Williams (U. of Washington)

This vast image is the result of two observing programs: the Panchromatic Hubble Andromeda Southern Treasury (PHAST) and the Panchromatic Hubble Andromeda Treasury (PHAT). PHAT and PHAST have made a large contribution to galactic science. PHAT started acquiring the images for this mosaic about a decade ago, and now we have this new image thanks to both efforts.

New research in the Astrophysical Journal presents the latest results from PHAST, including the new image. It’s titled “PHAST. The Panchromatic Hubble Andromeda Southern Treasury. I. Ultraviolet and
Optical Photometry of over 90 Million Stars in M31.” the lead author is Zhuo Chen from the Department of Astronomy at the University of Washington in Seattle.

Andromeda is not only our nearest neighbour but also the nearest spiral to us and the largest galaxy in the Local Group. Those facts aren’t just answers to trivia questions. They explain why astronomers can study the galaxy in detail, including assessing its stellar population, without some of the problems they face observing other galaxies.

“M31 studies circumvent complications from line-of-sight reddening, uncertain distances, and background/foreground confusion,” the researchers write in their paper. “Furthermore, such studies can be put into the context of the surrounding local environment, such as the ISM structure, the star formation rate (SFR), and the metallicity of the stars and gas, and even larger environment as mapped by
the Pan-Andromeda Archeological Survey.”

“Thus, M31 provides a unique and interesting comparison to the detailed information we have for our
Milky Way,” the authors explain.

This is a zoom-in of the full-resolution version of the image. You can download the full image and explore it for yourself here. Image Credit: NASA, ESA, B. Williams (U. of Washington)

One of the main takeaways from this massive observing effort is that the southern disk, which hadn’t been studied as intently as the northern disk, is fundamentally different from its counterpart. The southern disk appears to be more disturbed, indicating that it shows the effects of M31’s merger history more than the northern disk. The presence of M32, an early-type dwarf galaxy, hints at some of that merger history.

This image from the research shows the locations of the 13 “bricks” in PHAST (grey) and the 23 bricks from PHAT (blue.) Each of the new PHAST bricks consists of 15 HST pointings, each of which includes observations in two HST cameras: the Advanced Camera for Surveys and the Wide Field Camera 3. M32 is marked with an arrow in Brick 28. Image Credit: Chen et al. 2025.

Astronomers think that M32 could be what’s left of a galaxy that merged with Andromeda. Its properties are difficult to explain with our galaxy formation models. It could be the remnant core of a much more massive galaxy that was absorbed by Andromeda about two or three billion years ago.

“Andromeda’s a train wreck. It looks like it has been through some kind of event that caused it to form a lot of stars and then just shut down,” said study co-author Daniel Weisz at the University of California, Berkeley. “This was probably due to a collision with another galaxy in the neighborhood.”

One strong piece of evidence for that merger is the Giant Southern Stream. It’s a tidal debris stream made up of stars in Andromeda’s halo that could be a remnant from the ancient merger. The metallicity of its stars is generally lower than the stars in Andromeda’s bulge and disk.

This figure from older research shows Andromeda’s Giant Southern Stream and its proximity to M32. Image Credit: The Pan-Andromeda Archaeological Survey (PandAS).

The only way to understand Andromeda’s history is by surveying its stars. Thanks to PHAT and PHAST, astronomers now know 200 million individual stars. The observations are limited to stars brighter than the Sun, but the images are still scientifically rich. Together, they hint at a galaxy in transition.

“Andromeda looks like a transitional type of galaxy that’s between a star-forming spiral and a sort of elliptical galaxy dominated by aging red stars,” said Weisz. “We can tell it’s got this big central bulge of older stars and a star-forming disk that’s not as active as you might expect given the galaxy’s mass.”

“This detailed look at the resolved stars will help us to piece together the galaxy’s past merger and interaction history,” added PHAST’s Principal Investigator Ben Williams.

This figure from the research shows how the stellar density varies between regions in Andromeda. The zoom-in panels highlight the rich detail available at full HST resolution. Image Credit: Chen et al. 2025.

PHAST, together with PHAT, is a rich resource for astronomers studying Andromeda and, by extension, barred spirals everywhere, including our own Milky Way. However, before long, astronomers will get even better looks at Andromeda.

If all goes well, NASA will launch the Nancy Grace Roman Space Telescope in the near future. It’s an infrared telescope with a wide field of view, though it has the same size mirror. In a single exposure, the Roman can capture the equivalent of 100 high-resolution Hubble images, maybe more. It will help astronomers study the Giant Southern Stream in detail, along with other things, and will provide critical clues to Andromeda’s history.

The post Hubble Takes a 2.5 Gigapixel Image of Andromeda appeared first on Universe Today.

On a day that’s dolorous for many of us, let’s have some music. Here is a fantastic song by a fantastic band, featuring one of the greatest guitar solos in the history of rock: fifty short seconds of sublime inventiveness. The song is “Kid Charlemagne,” the band is of course Steely Dan, and the guitar solo is by Larry Carlton (b. 1948), a great studio musician who isn’t well known because he mostly backed up others. (I once saw him play as a solo act.)

Nearly all Steely Dan’s songs have opaque lyrics, but at least these lyrics were explained by the writers:

Writers Walter Becker and Donald Fagen have stated that the lyrics of “Kid Charlemagne” were loosely inspired by the rise and fall of the San Francisco-based LSD chemist Owsley Stanley, augmented with other images of the counterculture of the 1960s:

On the hill the stuff was laced with kerosene
But yours was kitchen clean
Everyone stopped to stare at your Technicolor motor home

The first two lines draw on the fact that Owsley’s LSD was famed for its purity. The “Technicolor motor home” of the third line is likely a reference to Furthur, the Merry Pranksters‘ modified school bus; Stanley supplied them with LSD.

The final verse describes Stanley’s 1967 arrest after his car reportedly ran out of gas:

Clean this mess up else we’ll all end up in jail
Those test tubes and the scale
Just get it all out of here
Is there gas in the car?
Yes, there’s gas in the car
I think the people down the hall know who you are.

More from Wikipedia:

Larry Carlton’s guitar solo starts at 2:18 into the song and ends at 3:08. Pete Prown and HP Newquist described it as consisting of “twisted single-note phrases, bends, and vibrant melody lines”; they called it and Carlton’s “joyous, off-the-cuff break” during the song’s fade-out “breathtaking.”  According to Rolling Stone, which ranked “Kid Charlemagne” at #80 in its list of the “100 Greatest Guitar Songs”: “In the late seventies, Steely Dan made records by using a revolving crew of great session musicians through take after take, which yielded endless jaw-dropping guitar solos. Larry Carlton’s multi-sectioned, cosmic-jazz lead in this cut may be the best of all: It’s so complex it’s a song in its own right.”  In 2022, Far Out Magazine listed it as the fourth-greatest guitar solo on a Steely Dan song, calling Carlton’s playing “intense, fluid, and frequently on the brink of spinning out of control”.[10] Nick Hornby, in Songbook, spoke of the solo’s “extraordinary and dexterous exuberance”, though he questioned its relationship with the “dry ironies of the song’s lyrics”.[11]

“It’s my claim to fame,” Carlton told Guitar World in 1981. “I did maybe two hours worth of solos that we didn’t keep. Then I played the first half of the intro, which they loved, so they kept that. I punched in for the second half. So it was done in two parts and the solo that fades out in the end was done in one pass.”

. . . Carlton called his solo on “Kid Charlemagne” the high point of his career at the time, saying, “I can’t think of anything else that I still like to listen to as strongly as that.”

Carlton also plays the “outro” at the end.

Rick Beato’s third episode of his well know What Makes This Song Great series was an analysis of “Kid Charlemagne”, and you can hear it here. It’s a good one.

Listening to Steely Dan songs and reading comments, I see that many people think that Donald Fagen has a horrible voice. I disagree. Yes, it’s nasal, but I thinks it fits very well with their unusual songs.

The band, which included many studio musicians, is vastly underrated, and I wonder if today’s young people even listen to its music. It is sui generis and unmistakable: a melange of jazz, rock, and ballads. Some of my other favorites are “Dr. Wu,” “Dirty Work,” “Bad Sneakers” (totally opaque), and, of course, the song below,” which mentions my alma mater William & Mary—one of the few rock songs to mention a college or university (can you name two others?) Oh, and the guitar-rich stop time during the song is great.

Becker (left) and Fagen:

Kotivalo, CC BY-SA 4.0, via Wikimedia Commons

There’s a Universe full of black holes out there, spinning merrily away—some fast, others more slowly. A recent survey of supermassive black holes reveals that their spin rates reveal something about their formation history.

If you want to describe a supermassive black hole’s characteristics, there are two important numbers to use. One is its mass and the other is its spin rate. Some black hole spin rates are thought to be very close to the speed of light. According to Logan Fries, a PhD student at the University of Connecticut, those numbers are tough to get. “The problem is that mass is hard to measure, and spin is even harder,” he said. Yet, having accurate numbers is important if we want to understand black hole evolution.

Fries and his colleagues in the Sloan Digital Sky Survey’s Reverberation Mapping Project took on a tough job. They measured the spin rates of black holes over cosmic history. “We have studied the giant black holes found at the centers of galaxies, from today to as far back as seven billion years ago,” said Fries, a primary author of a paper about this work. The mapping project also made detailed observations of the associated accretion disks. Those are the areas nearest the black hole where matter accumulates and heats up as it spirals in. Measuring that region is important since knowing the black hole’s mass and its accretion disk’s structure provides data that allows them to measure the spin rate. Astronomers typically estimate the spin rate by observing how matter behaves as it falls into the black hole.

The typical morphology of supermassive black holes. This artist’s impression depicts one surrounded by an accretion disc. Credit: ESO, ESA/Hubble, M. Kornmesser/N. Bartmann Black Holes and their Archaeology

The results of the SDSS Survey of mass measurements of hundreds of black holes were a surprise, according to Fries. That’s because the spin rates reveal something about the black holes’ formation history. “Unexpectedly, we found that they were spinning too fast to have been formed by galaxy mergers alone,” he said. “They must have formed in large part from material falling in, growing the black hole smoothly and speeding up its rotation.”

Fries described his work at a recent meeting of the American Astronomical Society. “I have read research papers that examine black hole spin, theoretically, from the lens of like black hole mergers, and I was curious if spin could be observationally measured,” said Fries. He pointed out that the history of black hole growth requires more precise measurements than have been available. And, they’re not easy, according to Fries’s thesis advisor, Physics professor Jonathan Trump. “The challenge lies in separating the spin of the black hole from the spin of the accretion disk surrounding it,” said Trump. “The key is to look at the innermost region, where gas is falling into the black hole’s event horizon. A spinning black hole drags that innermost material along for the ride, which leads to an observable difference when we look at the details in our measurements.”

Examples of black holes and accretion disks with various spin configurations: retrograde (black hole rotates in the opposite direction as the accretion disk), zero spin (does not rotate), and prograde (black hole rotates in the same direction as the accretion disk) from top to bottom, respectively. Examples of spectral energy distributions (SEDs) for each spin configuration are shown to the right of each cartoon with a vertical line drawn at the peak of the SED. The differences in the peak of the SEDs and how bright they are for different spin configurations demonstrate how astronomers measure black hole spin by fitting these models to observational data. (Contributed image using NASA illustrations)

Digging into the mass and spin of a black hole requires spectral measurements. Those made by the SDSS contain subtle shifts in the spectra toward shorter wavelengths of light. That shift is a major clue to the black hole’s rotation rate. “I call this approach ‘black hole archaeology,'” said Fries “because we’re trying to understand how the mass of a black hole has grown over time. By looking at the spin of the black hole, you’re essentially looking at its fossil record.”

What The Black Holes Tell Us

So, what does that fossil record tell us? First of all, it challenges the prevailing wisdom that black holes are always created in galaxy collisions. In other words, when galaxies merged, so did their central black holes. Each galaxy brings a rotation rate and orientation to the merger. The rotations could just as easily cancel each other out as they are to add together. If that is true, then the astronomers should have seen a wide range of spins. Some black holes should have a lot of spin, others… not so much.

The big surprise is that many black holes appear to spin very quickly. Even more amazing, the most distant ones seem to be spinning faster than the ones nearest to us (i.e. the “nearby” Universe). It’s as if they spin faster in the early Universe, and more slowly in more recent epochs. “We find that about 10 billion years ago, black holes acquired their mass primarily through eating things,” Fries explained.

The early fast spin rate implies that most supermassive black holes (like the one in our own Milky Way Galaxy) built up over time by taking in gas and dust in a very smooth and controlled manner. In other words, the more they eat (in the way of stars and gas), the faster their spin rate. It also turns out that merger growth actually slows the spin of supermassive black holes. That could explain why those we measure today have a mix of spin rates, rather than the more uniform rates of earlier epochs.

Future Directions

The idea of black holes forming smoothly over time provides a new direction for black hole research. Observations by JWST will help give more targets to study. Surveys such as the SDSS Reverberation Mapping project will follow up with more precise measurements of the huge supermassive black holes JWST continually finds as it studies the Universe.

For More Information

Spinning Black Holes Reveal How They Grew
‘Black Hole Archaeology’: Understanding How Black Holes Gained Their Mass

Black Hole Archaeology: Mapping the Growth History of Black Holes Across Cosmic Time (PDF of AAS presentation)

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