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    Don't Miss: NASA's first steps toward new moon mission via Orion trial

    Morfydd Clark (Galadriel)Amazon Studios
    Watch
    The Rings of Power takes us back to J. R. R. Tolkien’s Middle-earth, where Morfydd Clark (above) plays a younger (but still ancient) Galadriel in Amazon’s bid to tell Sauron’s origin story. On Prime Video from 2am BST on 2 September.
    Read
    Taxi from Another Planet records the unlikely conversations between astrobiologist Charles Cockell and taxi drivers about aliens and space exploration. So is Mars our plan B? Will we understand aliens? And what if we are alone? On sale from 30 August.

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    The Genetic Age review: Is genetic engineering a costly distraction?

    Matthew Cobb’s latest book is a disturbing history of genetic engineering, which asks whether it is worth the money – or the risk

    Humans

    24 August 2022

    By Michael Marshall
    Gene editing, exemplified by CRISPR technology, has elicited both hopes and fearsELLA MARU STUDIO/SCIENCE PHOTO LIBRARY
    The Genetic Age
    Matthew Cobb
    Profile Books
    FOR more than 50 years, biologists have been genetically engineering organisms in increasingly precise ways. From the early, crude methods of the 1960s and 1970s, to the modern “gene editing” exemplified by CRISPR technology, genetic engineering has elicited great hopes and terrifying fears.
    In his disturbing and readable new book The Genetic Age: Our perilous quest to edit life, biologist and science historian Matthew Cobb tells the story of this field. … More

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    Why I love the proliferation of green roofs and living walls

    Green roofs have existed for more than 2000 years, but, along with living walls, they are becoming more popular – and provide major eco-benefits, writes Beronda L. Montgomery

    Humans

    | Columnist

    24 August 2022

    By Beronda L. Montgomery
    JSMimages/Alamy
    SOME of my favourite writing spaces of late have had a living wall – a vertical garden of plants – or a bountiful green roof. There is something very soothing to me about being in a space with a visible, robust community of plants.
    Green roofs aren’t new: they have been reported to exist as early as 500 BC, in the Hanging Gardens of Babylon. But they appear to have become more common recently, or at least my noticing of them has become more frequent. I have seen them at hotels, restaurants and my current and former workspaces.
    Living walls and green … More

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    Nope review: Jordan Peele UFO horror is packed with interesting ideas

    Nope might adopt the flying saucer cliché, but this beautifully shot spectacle from director Jordan Peele breathes new life into the sci-fi horror genre

    Humans

    24 August 2022

    By Chen Ly
    L to R: Daniel Kaluuya, Keke Palmer, and Brandon Perea in NOPE, written, produced, and directed by Jordan Peele.Universal Pictures
    Nope
    Jordan Peele
    On general release
    SOMETHING strange is lurking in the clouds above a dusty, unassuming valley deep in southern California. On a horse ranch, taciturn Otis “OJ” Haywood Jr and his sister, the somewhat livelier Emerald, are struggling to save their business, Haywood’s Hollywood Horses, which supplies horses for film and television. Six months earlier, their father, who founded the business, was killed when a nickel mysteriously fell out of … More

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    Scientific illustrations illuminate work by Galileo, Einstein and more

    Taken from Anna EscardÓ’s book Science Illustration: A history of visual knowledge from the 15th century to today, these images range from Galileo’s watercolours to a sketch from Einstein’s notebook

    Humans

    24 August 2022

    By Gege Li
    TASCHEN
    THESE seminal scientific images, taken from the new book Science Illustration: A history of visual knowledge from the 15th century to today by Anna EscardÓ (published by Taschen), are more than just a treat for the eyes.
    The lateral view of the human brain, shown above, is taken from French physician and anatomist Jean-Baptiste Marc Bourgery’s Atlas of Human Anatomy and Surgery. First published in 1831, this textbook is known as the most comprehensive ever produced on human anatomy.Advertisement
    By courtesy of the Ministry of Cultural Heritage and Activities (MiBACT), Central National Library of Florence, Ban of Reproduction; The Hebrew University of Jerusalem; By courtesy of the Ministry of Cultural Heritage and Activities (MiBACT), Central National Library of Florence, Ban of Reproduction
    The three images above show, from left to right: nerve synapses called the calyces of Held, drawn in 1934 by Santiago RamÓn y Cajal, whose neuron doctrine showed that the nervous system isn’t continuous, but is made from discrete cells; Albert Einstein’s 1905 sketch of a puzzle game from his relativity notebook; and watercolour illustrations of the moon by Galileo Galilei, based on observations made with a telescope he constructed in 1609 that was powerful enough to examine objects in the night sky.
    NASA/T. Benesch, J. Carns
    Shown above is NASA’s 2012 image of two “doughnuts” of charged particles, or plasma, surrounding Earth, an example of how computer graphics have created more precise and realistic depictions of invisible phenomena. These rings are called Van Allen radiation belts. NASA launched two probes in 2012 to better understand these regions and space weather more widely.
    “Scientific illustrations allow the conveyance… of complex scientific concepts,” says EscardÓ. “Even today… it is still necessary to use illustration as a tool to capture images that can only be made through this medium.”

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    Writing Gaia review: The letters of James Lovelock and Lynn Margulis

    Nearly forty years of letters between the two scientists who co-developed the paradigm-changing Gaia hypothesis make for fascinating, humanising reading

    Humans

    24 August 2022

    By Adam Vaughan
    James Lovelock and Lynn Margulis corresponded for nearly 40 years.Tim Cuff/Alamy
    Writing Gaia
    Edited by Bruce Clarke and Sébastien Dutreuil
    Cambridge University Press
    HERE’S something for the archive: “The New Scientist one seems to have stirred up some interest including an amazing number of crank letters of a gentle and non-aggressive kind,” wrote the late independent scientist and polymath James Lovelock, in a letter to biologist Lynn Margulis.
    The “cranks” were responding to an article in this magazine, dated 6 February 1975. In it, Lovelock presented the idea and world view of Earth as a self-regulating system, the Gaia hypothesis, to a wider … More

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    Human ancestors may have walked on two legs 7 million years ago

    An analysis of thigh and forearm bones from Sahelanthropus tchadensis suggests the early hominin was mainly bipedal, but the claim is controversial

    Humans

    24 August 2022

    By Clare Wilson
    3D models of the femur and ulnae of Sahelanthropus tchadensisFranck Guy / PALEVOPRIM / CNRS – University of Poitiers
    The ancestors of humans may have been walking on two legs by about 7 million years ago – a million years earlier than had been thought. But the finding, which comes from analysing a damaged thigh bone and two forearm bones, is controversial.
    Estimates vary for when the ancestors of humans and chimpanzees split from each other but broadly converge on about 6 million years ago. This is also the age of the earliest fossil of a bipedal hominid, called Orrorin tugenensis.
    The thigh bone, or femur, analysed in the latest study was discovered in the Lake Chad Basin in Chad. It was among thousands of bone pieces initially uncovered in 2001, almost all of which weren’t from primates.Advertisement
    The first hominin fossils identified among the bone pieces were fragments of skull and a few teeth. These were identified as a new and very early hominin species named Sahelanthropus tchadensis, dating from about 6 to 7 million years ago.
    A later method of fossil dating, based on analysing different forms of the element beryllium, pushed the estimate further back to somewhere between 6.5 and 7.5 million years ago.
    In 2004, a femur found among the bone pieces was identified as potentially belonging to a hominin by Aude Bergeret-Medina and Roberto Macchiarelli at the University of Poitiers in France. They later lost access to it, but in 2020 they published work based on measurements and photographs that argued that its shape suggests the owner didn’t walk on two legs.
    Now, Franck Guy, who is also at the the University of Poitiers, and his colleagues, who still have access to the fossils, have published a full analysis of the femur as well as two forearm bones, including computed tomography scans to see their internal structure. It took so long partly because the team didn’t initially have the right expertise to analyse bones other than the skull, says Guy.
    It is unknown if all the hominin bones came from the same individual or from several, but the researchers have assumed they belong to S. tchadensis as this was the only large primate with bones found at the site.
    The researchers compared the S. tchadensis thigh and forearm bones with those from modern humans as well as chimpanzees, gorillas, orangutans and some extinct hominins and great apes. They conclude that S. tchadensis spent some time clambering in trees but usually walked on two legs, based on several features of the femur that they say are closer to those of modern humans than great apes that usually walk on four limbs. These include the distribution of thicker sections of the dense outer layer of bone, called the cortex, and the presence of a rough surface at the top of the femur where the buttock muscles attach.
    “When on the ground they would have preferred to move bipedally. [When in trees] they would sometimes choose to use clambering. All the features point to this kind of behaviour,” says Guy.

    But Macchiarelli isn’t convinced. This is partly because the small angle the femur makes with the pelvis is more similar to that seen in quadrupedal apes, he says. “It’s mechanistically unstable to walk on two legs with a small angle.”
    Other primates that mainly walk on four legs occasionally stand up and walk on two, which could be why S. tchadensis has some features of bipedalism, says Macchiarelli. “There’s a bipedal signal in any primate,” he says.
    Fred Spoor at the Natural History Museum in London says the authors “make a good case” for bipedalism, but that the debate is likely to continue. “Unless you have a time machine, you can’t go back and see for yourself,” he says.
    The question is an important one because more recent hominins such as the australopiths both walked on two legs and climbed in trees as recently as 3 to 4 million years ago, he says. “That would mean that for the first 3 million years [of our history] there was this mixed locomotion, and not much was happening.”
    Kelsey Pugh at the American Museum of Natural History in New York says it would be useful to compare the S. tchadensis femur with a wider range of living and extinct primates. “It will be vital for independent teams of palaeoanthropologists to study these exciting fossils in the coming months,” she says.
    Journal reference: Nature, DOI: 10.1038/s41586-022-04901-z
    Sign up to Our Human Story, a free monthly newsletter on the revolution in archaeology and human evolution

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    The discovery of the Kuiper Belt revamped our view of the solar system

    On a Hawaiian mountaintop in the summer of 1992, a pair of scientists spotted a pinprick of light inching through the constellation Pisces. That unassuming object — located over a billion kilometers beyond Neptune — would rewrite our understanding of the solar system.

    Rather than an expanse of emptiness, there was something, a vast collection of things in fact, lurking beyond the orbits of the known planets.

    The scientists had discovered the Kuiper Belt, a doughnut-shaped swath of frozen objects left over from the formation of the solar system.

    As researchers learn more about the Kuiper Belt, the origin and evolution of our solar system is coming into clearer focus. Closeup glimpses of the Kuiper Belt’s frozen worlds have shed light on how planets, including our own, might have formed in the first place. And surveys of this region, which have collectively revealed thousands of such bodies, called Kuiper Belt objects, suggest that the early solar system was home to pinballing planets.

    The humble object that kick-started it all is a chunk of ice and rock roughly 250 kilometers in diameter. It was first spotted 30 years ago this month.

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    Staring into space

    In the late 1980s, planetary scientist David Jewitt and astronomer Jane Luu, both at MIT at the time, were several years into a curious quest. The duo had been using telescopes in Arizona to take images of patches of the night sky with no particular target in mind. “We were literally just staring off into space looking for something,” says Jewitt, now at UCLA.

    An apparent mystery motivated the researchers: The inner solar system is relatively crowded with rocky planets, asteroids and comets, but there was seemingly not much out beyond the gas giant planets, besides small, icy Pluto. “Maybe there were things in the outer solar system,” says Luu, who now works at the University of Oslo and Boston University. “It seemed like a worthwhile thing to check out.”

    David Jewitt and Jane Luu, shown in Honolulu in the early 2000s, discovered the Kuiper Belt.D. Jewitt/UCLA

    Poring over glass photographic plates and digital images of the night sky, Jewitt and Luu looked for objects that moved extremely slowly, a telltale sign of their great distance from Earth. But the pair kept coming up empty. “Years went by, and we didn’t see anything,” Luu says. “There was no guarantee this was going to work out.”

    The tide changed in 1992. On the night of August 30, Jewitt and Luu were using a University of Hawaii telescope on the Big Island. They were employing their usual technique for searching for distant objects: Take an image of the night sky, wait an hour or so, take another image of the same patch of sky, and repeat. An object in the outer reaches of the solar system would shift position ever so slightly from one image to the next, primarily because of the movement of Earth in its orbit. “If it’s a real object, it would move systematically at some predicted rate,” Luu says.

    By 9:14 p.m. that evening, Jewitt and Luu had collected two images of the same bit of the constellation Pisces. The researchers displayed the images on the bulbous cathode-ray tube monitor of their computer, one after the other, and looked for anything that had moved. One object immediately stood out: A speck of light had shifted just a touch to the west.

    But it was too early to celebrate. Spurious signals from high-energy particles zipping through space — cosmic rays — appear in images of the night sky all of the time. The real test would be whether this speck showed up in more than two images, the researchers knew.

    Jewitt and Luu nervously waited until 11 p.m. for the telescope’s camera to finish taking a third image. The same object was there, and it had moved a bit farther west. A fourth image, collected just after midnight, revealed the object had shifted position yet again. This is something real, Jewitt remembers thinking. “We were just blown away.”

    The way the circled object shifted position in the sky (time stamps at right) told Jewitt and Luu that the object, dubbed 1992 QB1, was distant. It was the first evidence of the icy zone called the Kuiper Belt.D. Jewitt/UCLA

    Based on the object’s brightness and its leisurely pace — it would take nearly a month for it to march across the width of the full moon as seen from Earth — Jewitt and Luu did some quick calculations. This thing, whatever it was, was probably about 250 kilometers in diameter. That’s sizable, about one-tenth the width of Pluto. It was orbiting far beyond Neptune. And in all likelihood, it wasn’t alone.

    Although Jewitt and Luu had been diligently combing the night sky for years, they had observed only a tiny fraction of it. There were possibly thousands more objects out there like this one just waiting to be found, the two concluded.

    The realization that the outer solar system was probably teeming with undiscovered bodies was mind-blowing, Jewitt says. “We expanded the known volume of the solar system enormously.” The object that Jewitt and Luu had found, 1992 QB1 (SN: 9/26/92, p. 196), introduced a whole new realm.

    Just a few months later, Jewitt and Luu spotted a second object also orbiting far beyond Neptune (SN: 4/10/93, p. 231). The floodgates opened soon after. “We found 40 or 50 in the next few years,” Jewitt says. As the digital detectors that astronomers used to capture images grew in size and sensitivity, researchers began uncovering droves of additional objects. “So many interesting worlds with interesting stories,” says Mike Brown, an astronomer at Caltech who studies Kuiper Belt objects.

    Finding all of these frozen worlds, some orbiting even beyond Pluto, made sense in some ways, Jewitt and Luu realized. Pluto had always been an oddball; it’s a cosmic runt (smaller than Earth’s moon) and looks nothing like its gas giant neighbors. What’s more, its orbit takes it sweeping far above and below the orbits of the other planets. Maybe Pluto belonged not to the world of the planets but to the realm of whatever lay beyond, Jewitt and Luu hypothesized. “We suddenly understood why Pluto was such a weird planet,” Jewitt says. “It’s just one object, maybe the biggest, in a set of bodies that we just stumbled across.” Pluto probably wouldn’t be a member of the planet club much longer, the two predicted. Indeed, by 2006, it was out (SN: 9/2/06, p. 149).

    Up-close look

    The discovery of 1992 QB1 opened the world’s eyes to the Kuiper Belt, named after Dutch-American astronomer Gerard Kuiper. In a twist of history, however, Kuiper predicted that this region of space would be empty. In the 1950s, he proposed that any occupants that might have once existed there would have been banished by gravity to even more distant reaches of the solar system.

    In other words, Kuiper anti-predicted the existence of the Kuiper Belt. He turned out to be wrong.

    Today, researchers know that the Kuiper Belt stretches from a distance of roughly 30 astronomical units from the sun — around the orbit of Neptune — to roughly 55 astronomical units. It resembles a puffed-up disk, Jewitt says. “Superficially, it looks like a fat doughnut.”

    The frozen bodies that populate the Kuiper Belt are the remnants of the swirling maelstrom of gas and dust that birthed the sun and the planets. There’s “a bunch of stuff that’s left over that didn’t quite get built up into planets,” says astronomer Meredith MacGregor of the University of Colorado Boulder. When one of those cosmic leftovers gets kicked into the inner solar system by a gravitational shove from a planet like Neptune and approaches the sun, it turns into an object we recognize as a comet (SN: 9/12/20, p. 14). Comets that circle the sun once only every 200 years or more typically derive from the solar system’s even more distant repository of icy bodies known as the Oort cloud.

    There are many places in the solar system where icy bodies congregate: the asteroid belt roughly between Jupiter and Mars (top), the doughnut-shaped Kuiper Belt beyond the gas giant planets (middle) and the most distant zone, the Oort cloud (bottom).Mark Garlick/Science Source

    In scientific parlance, the Kuiper Belt is a debris disk (SN Online: 7/28/21). Distant solar systems contain debris disks, too, scientists have discovered. “They’re absolutely directly analogous to our Kuiper Belt,” MacGregor says.

    In 2015, scientists got their first close look at a Kuiper Belt object when NASA’s New Horizons spacecraft flew by Pluto (SN Online: 7/15/15). The pictures that New Horizons returned in the following years were thousands of times more detailed than previous observations of Pluto and its moons. No longer just a few fuzzy pixels, the worlds were revealed as rich landscapes of ice-spewing volcanoes and deep, jagged canyons (SN: 6/22/19, p. 12; SN Online: 7/13/18). “I’m just absolutely ecstatic with what we accomplished at Pluto,” says Marc Buie, an astronomer at the Southwest Research Institute in Boulder, Colo., and a member of the New Horizons team. “It could not possibly have gone any better.”

    But New Horizons wasn’t finished with the Kuiper Belt. On New Year’s Day of 2019, when the spacecraft was almost 1.5 billion kilometers beyond Pluto’s orbit, it flew past another Kuiper Belt object. And what a surprise it was. Arrokoth — its name refers to “sky” in the Powhatan/Algonquian language — looks like a pair of pancakes joined at the hip (SN: 12/21/19 & 1/4/20, p. 5; SN: 3/16/19, p. 15). Roughly 35 kilometers long from end to end, it was probably once two separate bodies that gently collided and stuck. Arrokoth’s bizarre structure sheds light on a fundamental question in astronomy: How do gas and dust clump together and grow into larger bodies?

    One long-standing theory, called planetesimal accretion, says that a series of collisions is responsible. Tiny bits of material collide and stick together on repeat to build up larger and larger objects, says JJ Kavelaars, an astronomer at the University of Victoria and the National Research Council of Canada. But there’s a problem, Kavelaars says.

    In 2019, New Horizons flew by Arrokoth (above), a roughly 35-kilometer-long Kuiper Belt object.NASA, JHU-APL, SWRI

    As objects get large enough to exert a significant gravitational pull, they accelerate as they approach one another. “They hit each other too fast, and they don’t stick together,” he says. It would be unusual for a large object like Arrokoth, particularly with its two-lobed structure, to have formed from a sequence of collisions.

    More likely, Arrokoth was born from a process known as gravitational instability, researchers now believe. In that scenario, a clump of material that happens to be denser than its surroundings grows by pulling in gas and dust. This process can form planets on timescales of thousands of years, rather than the millions of years required for planetesimal accretion. “The timescale for planet formation completely changes,” Kavelaars says.

    If Arrokoth formed this way, other bodies in the solar system probably did too. That may mean that parts of the solar system formed much more rapidly than previously believed, says Buie, who discovered Arrokoth in 2014. “Already Arrokoth has rewritten the textbooks on how solar system formation works.”

    What they’ve seen so far makes scientists even more eager to study another Kuiper Belt object up close. New Horizons is still making its way through the Kuiper Belt, but time is running out to identify a new object and orchestrate a rendezvous. The spacecraft, which is currently 53 astronomical units from the sun, is approaching the Kuiper Belt’s outer edge. Several teams of astronomers are using telescopes around the world to search for new Kuiper Belt objects that would make a close pass to New Horizons. “We are definitely looking,” Buie says. “We would like nothing better than to fly by another object.”

    All eyes on the Kuiper Belt

    Astronomers are also getting a wide-angle view of the Kuiper Belt by surveying it with some of Earth’s largest telescopes. At the Canada-France-Hawaii Telescope on Mauna Kea — the same mountaintop where Jewitt and Luu spotted 1992 QB1 — astronomers recently wrapped up the Outer Solar System Origins Survey. It recorded more than 800 previously unknown Kuiper Belt objects, bringing the total number known to roughly 3,000.

    The Canada-France-Hawaii Telescope, near the summit of Mauna Kea on Hawaii’s Big Island, has revealed hundreds of Kuiper Belt objects.Gordon W. Myers/Wikimedia Commons (CC BY-SA 4.0)

    This cataloging work is revealing tantalizing patterns in how these bodies move around the sun, MacGregor says. Rather than being uniformly distributed, the orbits of Kuiper Belt objects tend to be clustered in space. That’s a telltale sign that these bodies got a gravitational shove in the past, she says.

    The cosmic bullies that did that shoving, most astronomers believe, were none other than the solar system’s gas giants. In the mid-2000s, scientists first proposed that planets like Neptune and Saturn probably pinballed toward and away from the sun early in the solar system’s history (SN: 5/5/12, p. 24). That movement explains the strikingly similar orbits of many Kuiper Belt objects, MacGregor says. “The giant planets stirred up all of the stuff in the outer part of the solar system.”

    Refining the solar system’s early history requires observations of even more Kuiper Belt objects, says Meg Schwamb, an astronomer at Queen’s University Belfast in Northern Ireland. Researchers expect that a new astronomical survey, slated to begin next year, will find roughly 40,000 more Kuiper Belt objects. The Vera C. Rubin Observatory, being built in north-central Chile, will use its 3,200-megapixel camera to repeatedly photograph the entire Southern Hemisphere sky every few nights for 10 years. That undertaking, the Legacy Survey of Space and Time, or LSST, will revolutionize our understanding of how the early solar system evolved, says Schwamb, a cochair of the LSST Solar System Science Collaboration.

    The Vera C. Rubin Observatory in Chile is expected to spot about 40,000 Kuiper Belt objects with its 8.4-meter mirror and the world’s largest digital camera.Rubin Observatory/NSF and AURA

    It’s exciting to think about what we might learn next from the Kuiper Belt, Jewitt says. The discoveries that lay ahead will be possible, in large part, because of advances in technology, he says. “One picture with one of the modern survey cameras is roughly a thousand pictures with our setup back in 1992.”

    But even as we uncover more about this distant realm of the solar system, a bit of awe should always remain, Jewitt says. “It’s the largest piece of the solar system that we’ve yet observed.” More