Ancient DNA pulls back curtain on the Sahara Desert's greener past
That's largely the case today, but 7,000 years ago the vast desert was an altogether different place: a verdant world of trees and rivers and home to megafauna such as hippos and elephants.
Over the past decades, scientists have gleaned details of the 'green Sahara.' Now, with the help of ancient DNA from mummified remains, geneticists are figuring out who once lived there.
The Takarkori rock shelter — situated in southwestern Libya's Tadrart Acacus mountains — offers a remarkable glimpse into the Sahara's greener past.
Archaeologists uncovered the remains of 15 women and children at the site two decades ago.
Initial attempts to extract ancient DNA from the remains fell flat. Cool and constant conditions — the opposite of the extreme temperature swings of today's Sahara — yield the best preserved DNA.
New techniques made it possible to sequence the genome — a complete set of genetic material — of two mummified women. The analysis revealed intriguing information about the ancestry of the Takarkori people and how they adopted a herding way of life.
Dark energy is a mysterious force that accelerates the expansion of the universe, and it's thought to represent about 70% of the energy in the cosmos.
New clues from the Dark Energy Spectroscopic Instrument collaboration, known as DESI, suggest dark energy may be behaving in unexpected ways and may even be weakening over time.
The collaboration, now in its fourth year of surveying the sky, has released its latest batch of data. While it's not the final word, the information has space scientists excited.
'We're in the business of letting the universe tell us how it works, and maybe the universe is telling us it's more complicated than we thought it was,' said Andrei Cuceu, a postdoctoral researcher at the Lawrence Berkeley National Laboratory, which manages DESI.
A SpaceX Falcon 9 rocket sent four tourists in a Crew Dragon capsule on a polar orbit never attempted before.
Spearheading the Fram2 mission was Malta resident Chun Wang, who made his fortune running Bitcoin mining operations. He paid SpaceX an undisclosed sum for this trip.
Watch a video of the spacecraft's splashdown off California's coast on Friday after Wang and his crewmates — film director Jannicke Mikkelsen, robotics researcher Rabea Rogge and adventurer Eric Philips — spent 3.5 days in low-Earth orbit.
It was the first journey to space for each of the four crew members, who all have ties to polar land exploration.
Meanwhile, NASA's Suni Williams and Butch Wilmore spoke out this week for the first time following a protracted nine-month mission to space. Here's what they had to say.
To the untrained eye, stone tools may look like ordinary rocks, but to specialists they have fascinating stories to tell.
Researchers have found stone artifacts crafted in a style closely associated with Neanderthals in East Asia for the first time at a site in southwestern China's Yunnan province.
The discovery, dating back 60,000 to 50,000 years, has puzzled archaeologists, who have come up with competing hypotheses to explain the stone tools.
Perhaps Neanderthals could have migrated east and reached what's now China, or a different species of ancient human possibly made tools uncannily similar to those unearthed in Europe.
Either way, the answer could shake up what's known about human origins during the Stone Age.
Ancestors of T. rex and their plant-eating prey would have congregated to drink water from a lagoon on what's now Scotland's Isle of Skye, according to an analysis of newly identified dinosaur footprints.
Lead study author Tone Blakesley said he was among a small group that recognized an initial three footprints at the remote site on the isle's Trotternish Peninsula in 2019 when he was a graduate student at the University of Edinburgh.
'It was very exciting,' Blakesley said. Documenting a total of 131 footprints, he used a drone to take thousands of overlapping images of the site before producing digital 3D models of the tracks. They are preserved in 'exquisite detail,' he added.
Dive into these remarkable stories.
— The discovery of a mystery king's tomb in Abydos, Egypt, is revealing fresh clues about a long-lost dynasty notoriously missing from records of pharaohs who once ruled the region.
— Scientists sent a container of cooked soybean paste to the International Space Station, where it was left to ferment before returning to Earth as miso. Here's how it tasted.
— An eerie spiral recently lit up European skies, and it's becoming a more common sight.
— Archaeologists excavating a massive tomb in Pompeii unearthed extremely rare, nearly life-size marble statues that shed new light on the power held by priestesses in the ancient city.
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The Hill
6 hours ago
- The Hill
Critics shouldn't block NASA's nuclear path to a moon base
Sean Duffy, NASA's interim administrator, proved that the U.S. is serious about establishing a lunar base when he announced the deployment of a 100-kilowatt nuclear reactor on the moon by 2030. The idea, although a sound one, is not without its critics. The announcement that the first element of a lunar base will be a nuclear reactor was logical. Nuclear power, unlike solar, is available 24/7 and thus does not require backup batteries during periods when the sun is not available. That the reactor is first means that every other element of the lunar base can be hooked up and powered up immediately. As NPR notes, a 100-kilowatt reactor on Earth would be able to power 70 to 80 private homes in the United States, so it could power a decent-sized lunar base. It would have to withstand the extremes of heat and cold on the moon, not to mention the possibility of moonquakes and meteor strikes. Instead of water to cool it, the reactor would simply radiate the heat it creates into space. The cost would be about $3 billion. Space lawyer Michelle Hanlon describes some of the legal aspects of placing a nuclear reactor on the moon, especially in context of the space race with China. While the Outer Space Treaty prohibits claims of national sovereignty on the moon, the establishment of a nuclear reactor, especially with a lunar base attached to it, grants the nation-state that does it some measure of control over the surrounding territory. Its Article IX requires that states act 'with due regard to the corresponding interests of all other States Parties to the Treaty.' The practical effect of the Article IX provision is that the first country to establish a lunar base on the moon's south pole would be able to claim control over some prime real estate, important where ice mining is likely to be an essential enterprise. Duffy is therefore correct that the U.S. and its allies should be first with a nuclear reactor and a lunar base before China can establish its own and thus exert control. The idea of a nuclear-powered lunar base is not without its critics. For example, a CBS News host opined that colonizing the moon was akin to the colonization of native peoples on Earth by European powers. Celebrity astrophysicist Neil deGrasse Tyson set him straight by pointing out that no native peoples exist on the moon or anywhere else in the solar system beyond Earth. The exchange elicited eyerolling on the Fox News show 'The Five.' But even there, some griping occurred. Dana Perino, who used to work for President George W. Bush, expressed considerable ennui about the whole concept of space travel. From the perspective of someone who has seen a space shuttle launch in person and watched men walk on the moon live on television, the attitude seems to be bizarre and dispiriting. Tyrus, the former wrestler turned social and political commentator, trotted out the 'let's solve problems on Earth before we go into space' trope that has been around since the beginning of the space age. The obvious answer has always been, 'Do both.' Ross Marchand, writing for Real Clear Science, noted the $37 trillion national debt and then claimed that building a lunar base would be just too expensive. He undermined his argument by comparing the 100-kilowatt lunar nuclear power plant to the 1-gigawatt reactors that exist on Earth and cost $10 billion to build (largely because of permitting and environmental regulation problems). Then he increased the estimated cost by a factor of 10 'or more.' Although NASA projects often do suffer cost overruns, $3 billion to $100 billion would be a little much, even for the space agency with its history of inefficiency. Marchand also trotted out the 'robots can explore space cheaper and better than humans' claim that was soundly debunked by the late, great lunar geologist Paul Spudis. In fact, returning to the moon and going on to Mars also polls well and has bipartisan political support, even it still has its critics. No great endeavor ever undertaken since the beginning of civilization has not had people saying it can't or shouldn't be done. The International Space Station, for example, drew fierce opposition and was almost cancelled more than once. The orbiting space laboratory is currently churning out a stream of scientific discoveries and technological innovations, confounding its early critics, who are long since forgotten. The lunar base and even Elon Musk's planned Mars colony will undergo a similar process. Future generations will find it difficult to imagine a universe where humans just occupied one world. Mark R. Whittington, who writes frequently about space policy, has published a political study of space exploration entitled ' Why is It So Hard to Go Back to the Moon? ' as well as ' The Moon, Mars and Beyond,' and, most recently,' Why is America Going Back to the Moon? ' He blogs at Curmudgeons Corner.
Yahoo
6 hours ago
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Astronomers Say They've Finally Solved the 'Little Red Dots' Mystery
When the James Webb Space Telescope first came online in 2022, it immediately spotted something astronomers had never seen before: "little red dots" peppering the ancient expanse of deep space, originating from around when the universe was just one billion years old. Ever since, we've struggled to explain what these faint signals could be. The prevailing theory is that they're some kind of extremely compact galaxy. But at only two percent of the diameter of the Milky Way, the distribution of stars would have to be impossibly dense, perhaps more so than our current laws of physics allow. They're also too faint to be produced by a quasar, a type of supermassive black hole that is actively devouring matter, which it causes to heat up and glow. Moreover, the black holes would be "overmassive" for such a small galaxy, scientists argue. Now, famed Harvard astronomer Avi Loeb (or infamous, depending on how you view his speculative theories regarding aliens) and his colleague Fabio Pacucci believe they have an answer. In a new study published in the Astrophysical Journal Letters, the pair reinforce the idea that the family of red oddities are, in fact, galaxies — but are unusually tiny because they haven't started spinning up to speed yet. It's a hypothesis rooted in one of the leading theories for galaxy formation, which holds that these structures form in "halos" of dark matter, the invisible substance thought to account for 85 percent of all mass in the cosmos. While we can't see or interact with dark matter, it does exert a significant gravitational influence, which explains how the largest structures in the cosmos came together and took shape. In the study, the astronomers propose that the diminutive galaxies formed in halos that just so happened to be among the slowest spinning in the cosmos, with 99 percent of halos spinning faster. The idea, in principle, is simple. If you held out a piece of rope in one hand and started spinning in place, the rope would stretch out and reach farther. But if you slowed down, the rope would slump to the ground. This hypothesis would explain why we're only seeing the dots at such a nascent period of the universe. Over time, the halos would inevitably speed up, and their constituent galaxies would expand. "Dark matter halos are characterized by a rotational velocity: some of them spin very slowly, and others spin more rapidly," Loeb said in a statement about the work. "We showed that if you assume the little red dots are typically in the first percentile of the spin distribution of dark matter halos, then you explain all their observational properties." It's a compelling theory — but it's not the only game in town. Recently, two teams of astronomers found clues that what we're witnessing may actually be an entirely new class of cosmic object: "black hole stars." Their work suggests the glowing dots are an active supermassive black hole surrounded by a vast and thick shell of gas. The intense radiation of the black hole heats up the shell, which absorbs most of the emissions, dimming the light to an outside observer. In many ways, it resembles a star blown up to epic proportions — except, instead of nuclear fusion powering the center, there's a voracious black hole churning through matter. Loeb and Pacucci's theory doesn't address whether these slow-spinning galaxies have a black hole at their center, but suggests that they could form one. "Low-spin halos tend to concentrate mass in the center, which makes it easier for a black hole to accrete matter or for stars to form rapidly," Pacucci said in the statement. The luminous red dots, he added, "might help us understand how the first black holes formed and co-evolved with galaxies in the early universe." More on space: Astronomers in Awe of Terrifying "Eye of Sauron" That's Pointed Straight at Earth Solve the daily Crossword
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7 hours ago
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Hubble Captures Glorious New Image of That Mysterious Object Cruising Into Our Solar System
As the mysterious interstellar object known as 3I/ATLAS plummets through our Solar System, NASA's good old Hubble Space Telescope has captured the best look yet at the interstellar visitor. On July 21, the interstellar interloper passed close enough to Earth — and to Hubble, which orbits us at about 320 miles above the planet — that the veteran space telescope was able to capture a surprisingly detailed image of it, NASA explains in a statement about the image. In the space agency's incredible shot — the second the Hubble has captured since the discovery of 3I/ATLAS — a "teardrop-shaped cocoon of dust," as NASA calls it, is seen trailing behind the puzzling object, which many scientists suspect is a sizable interstellar comet. Discovered a mere five weeks ago on July 1, 3I/ATLAS is only the third known interstellar object to pass through our solar system, with the first being the ever-mysterious 'Oumuamua back in 2017. As with that strangely elongated visitor, there is some speculation that 3I/ATLAS could be some sort of alien spacecraft — but NASA believes we're looking at the "solid, icy nucleus" of a comet. That said, there's quite a lot about this interstellar visitor that is extraordinary — and unexplained. In an editorial for last month, a pair of astrophysicists posited that 3I/ATLAS is much older than 'Oumuamua and 3I/Borisov, the second-ever recorded interstellar object discovered by amateur astronomer Gennadiy Borisov back in 2019. Those scientists, University of Michigan, Ann Arbor's Aster Taylor and Michigan State University's Darryl Seligman, suggested that this latest interstellar interloper could be anywhere from three to 11 billion years old, and cited its massive speeds of 134,000 mph relative to the Sun as the source of their hypothesis. "Since the influence of the galaxy tends to speed up objects over time," the astrophysicists wrote, "this velocity implies that ATLAS is far older." NASA has, meanwhile, proffered in its latest findings, which have been accepted into the Astrophysical Journal Letters, that 3I/ATLAS' nucleus may be as large as 3.5 miles across or as small as just 1,000 feet in diameter. The new Hubble image played a big role in those estimates, though as the agency noted in another statement, the "solid heart of the comet presently cannot be directly seen, even by Hubble." While scientists continue to glean bits and pieces of information about this out-of-solar-system visitor, there's still one huge, outstanding question about 3I/ATLAS. "No one knows where the comet came from," explained Hubble science leader David Jewitt in the statement. "It's like glimpsing a rifle bullet for a thousandth of a second. You can't project that back with any accuracy to figure out where it started on its path." More on comets: Scientists Just Found Something Very Weird About the Mysterious Object Hurtling Into Our Solar System Solve the daily Crossword
