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    An Antarctic ice dome may offer the world’s clearest views of the night sky

    An observatory in the heart of Antarctica could have the world’s clearest views of the night sky.
    If an optical telescope were built on a tower a few stories tall in the middle of the Antarctic Plateau, it could discern celestial features about half the size of those typically visible to other observatories, researchers report online July 29 in Nature. The observatory would achieve such sharp vision by peering above the atmosphere’s lowermost layer, known as the boundary layer, responsible for much of the undulating air that muddles telescope images (SN: 10/4/18).
    The thickness of Earth’s boundary layer varies across the globe. Near the equator, it can be hundreds of meters thick, limiting the vision of premier optical telescopes in places like the Canary Islands and Hawaii (SN: 10/14/19). Those telescopes usually cannot pick out celestial features smaller than 0.6 to 0.8 arc seconds — the apparent width of a human hair from about 20 meters away.
    “But in Antarctica, the boundary layer is really thin,” says Bin Ma, an astronomer at the Chinese Academy of Sciences in Beijing, “so it is possible to put a telescope above.”
    Ma and colleagues took the first-ever measurements of nighttime atmospheric blur from the highest point in East Antarctica, called Dome A. From April to August 2019, instruments on an 8-meter-tall tower at China’s Kunlun research station tracked how Earth’s atmospheric turbulence distorted incoming starlight. A nearby weather station also monitored atmospheric conditions, such as temperature and wind speed. Using these observations, researchers characterized the boundary layer at Dome A and its effect on telescope observations.
    From April to August 2019, instruments atop an 8-meter-tall tower at China’s Kunlun research station in East Antarctica observed how the local atmosphere distorted light from celestial objects.Zhaohui Shang
    The boundary layer was, on average, about 14 meters thick; as a result, the light sensors at the top of the 8-meter tower were completely free of boundary layer blur only about one-third of the time. But when these instruments were above the layer, atmospheric interference was so low that a telescope could pick out details on the sky 0.31 arc seconds across, on average. The best recorded atmospheric conditions would let a telescope see features as small as 0.13 arc seconds.
    “One-tenth of an arc second is extremely good,” says Marc Sarazin, an applied physicist at the European Southern Observatory in Munich who was not involved in the work. This is “really something you rarely achieve in Chile or on Mauna Kea” in Hawaii.
    Researchers have found similarly excellent visibility above the boundary layer at another spot on the Antarctic Plateau, known as Dome C. But the boundary layer there is around 30 meters thick — making it more difficult to build an observatory above it. An optical telescope planned for construction on a 15-meter tower at Kunlun could take advantage of Dome A’s stellar views above the boundary layer, Ma says. Such crisp telescope images could help astronomers study a range of celestial objects, from solar system bodies to distant galaxies.

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    The illnesses caused by a disconnect between brain and mind

    A group of troubling disorders including functional neurological disorders can lead to very real symptoms, but tests suggest nothing is wrong. Finding out why is shedding new light on the nature of consciousness itself. Jamie Lacelle suffers from a functional neurological disorder. This is her story. More

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    James Lovelock says artificial intelligence is the start of new life

    In his new book Novacene, James Lovelock says the creation of AlphaGo was the start of a new kingdom of life that will create and think for itself. He’s optimistic that this new kingdom of life will want to keep us around like we keep plants in gardens. In our interview at his house near Chesil Beach we discuss the future of Gaia, our new AI overlords and why Elon Musk’s Mars mission is crazy. More

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    Lee Berger: Rewriting human history

    Recent discoveries of fossils of ancient human relatives in southern Africa are disrupting our long-held ideas of the origins of humankind. Two of these discoveries, Australopithecus sediba and Homo naledi, represent significant contributions to this shakeup of our family tree. And there’s much more to come, as Berger explains in this interview with New Scientist […] More

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    Richard Dawkins: How we can outgrow God and religion

    Richard Dawkins is one of the world’s most famous scientists, a best-selling author – and a hugely controversial figure. His works on evolutionary biology inspired millions, but his bestselling book The God Delusion started a new phase of his career as an outspoken critic of all things religious. We met him at his home in Oxford to find out more. More

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    The star cluster closest to Earth is in its death throes

    The closest cluster of stars to Earth is falling apart and will soon die, astronomers say.
    Using the Gaia spacecraft to measure velocities of stars in the Hyades cluster and those escaping from it, researchers have predicted the cluster’s demise. “We find that there’s only something like 30 million years left for the cluster to lose its mass completely,” says Semyeong Oh, an astronomer at the University of Cambridge.
    “Compared to the Hyades’ age, that’s very short,” she says. The star cluster, just 150 light-years away and visible to the naked eye in the constellation Taurus, formed about 680 million years ago from a large cloud of gas and dust in the Milky Way.
    Stellar gatherings such as the Hyades, known as open star clusters, are born with hundreds or thousands of stars that are held close to one another by their mutual gravitational pull. But numerous forces try to tear them apart: Supernova explosions from the most massive stars eject material that had been binding the cluster together; large clouds of gas pass near the cluster and yank stars out of it; the stars themselves interact with one another and jettison the least massive ones; and the gravitational pull of the whole Milky Way galaxy lures stars away too. As a result, open star clusters rarely reach their billionth birthday.

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    The Hyades has survived longer than many of its peers. But astronomers first saw signs of trouble there in 2018, when teams in Germany and Austria independently used the European Space Agency’s Gaia space observatory to find numerous stars that had escaped the cluster. These departing stars form two long tails on opposite sides of the Hyades — the first ever seen near an open star cluster. Each stellar tail stretches hundreds of light-years and dwarfs the cluster itself, which is about 65 light-years across.
    In the new work, posted July 6 at arXiv.org, Oh and Cambridge colleague N. Wyn Evans analyzed how the cluster has lost stars over its life. It was born with about 1,200 solar masses but now has only 300 solar masses left. In fact, the two tails of escapees possess more stars than does the cluster. And the more stars the cluster loses, the less gravity it has to hold on to its remaining members, which leads to the escape of additional stars, exacerbating the cluster’s predicament.

    Siegfried Röser, an astronomer at Heidelberg University in Germany who led one of the two teams that discovered the cluster’s tails, agrees that the Hyades is in its sunset years. But he worries that it’s too early to pin a precise date on the funeral. “That seems to be a little bit risky to say,” Röser says. Running a computer simulation with the stars’ masses, positions and velocities should better show what will happen in the future, he says.
    The main culprit behind the cluster’s coming demise, Oh says, is the Milky Way. Just as the moon causes tides on Earth, lifting the seas on both the side facing the moon and the side facing away, so the galaxy exerts tides on the Hyades: The Milky Way pulls stars out of the side of the cluster that faces the galactic center as well as the cluster’s far side.
    Even millions of years after the cluster disintegrates, its stars will continue to drift through space with similar positions and velocities, like parachutists jumping out of the same airplane. “It’s still probably going to be detectable as a coherent structure in position-velocity space,” Oh says, but the stars will be so spread out from one another that they will no longer constitute a star cluster. More