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A new study published in Nature Astronomy provides evidence that our solar system passed through a dense interstellar cloud 2 \u2013 3 million years ago, exposing Earth to higher cosmic radiation and altering the climate. The discovery suggests that the Sun\u2019s location in space might shape Earth\u2019s history more than it was previously considered.<\/strong><\/p>\n A collaborative effort by astronomers from Boston University, Harvard University, and Johns Hopkins University found evidence that some two to three million years ago, our solar system encountered a dense interstellar cloud that shrank the heliosphere to just 0.22 AU \u2014 or about 33 million km (20 million miles), causing drastic changes on Earth.<\/p>\n The heliosphere \u2014 made from a constant flow of charged particles from the Sun (solar wind) \u2014 normally stretches well past Pluto and acts as a plasma shield from cosmic radiation and galactic rays which can alter DNA.<\/p>\n Using computer models, authors of the study visualized where the Sun, heliosphere and the rest of our solar system were positioned 2 million years ago and then mapped the path of the Local Ribbon of Cold Clouds system \u2014 a string of large, dense, very cold clouds mostly made of hydrogen atoms.<\/p>\n Researchers propose that one of the clouds close to the end of that ribbon, named the Local Lynx of Cold Cloud, could have collided with the heliosphere, fully exposing Earth and other planets to the interstellar medium \u2014 a mix of dust, gas and leftover atomic elements of exploded stars.<\/p>\n According to the paper, this aligns with geological evidence that shows increased 60<\/sup>Fe (iron 60) and 244<\/sup>Pu (plutonium 244) isotopes in the ocean, Antarctic snow, and ice cores\u2014and on the moon\u2014from the same time period.<\/p>\n The timing also matches with temperature records that indicate a cooling period.<\/p>\n \u201cThe outside pressure from the Local Lynx of Cold Cloud could have continually blocked out the heliosphere for a couple of hundred years to a million years, depending on the size of the cloud,\u201d said Merav Opher, Boston University space physicist, an expert on the heliosphere and lead author of the paper.<\/p>\n Opher said the heliosphere again engulfed the solar system as soon it was away from the cold cloud, and that\u2019s how it is today.<\/p>\n \u201cThis paper is the first to quantitatively show there was an encounter between the Sun and something outside of the solar system that would have affected Earth\u2019s climate,\u201d Opher said.<\/p>\n \u201cStars move, and now this paper is showing not only that they move, but they encounter drastic changes.\u201d<\/p>\n In an article released by Boston University on June 10, Jessica Colarossi said Opher\u2019s models have quite literally shaped our scientific understanding of the heliosphere, and how it is structured by the solar wind pushing up against the interstellar medium.<\/p>\n \u201cHer theory is that the heliosphere is shaped like a puffy croissant, an idea that shook the space physics community. Now, she\u2019s shedding new light on how the heliosphere, and where the Sun moves through space, could affect Earth\u2019s atmospheric chemistry,\u201d Colarossi said.<\/p>\n While it\u2019s impossible to know the exact effect the cold cloud had on Earth there are a couple of other cold clouds in the interstellar medium that the Sun has likely encountered in the billions of years since it was born, Opher says. And it will probably stumble across more in another million years or so.<\/p>\n References:<\/p>\n 1<\/sup> The Solar System May Have Passed through Dense Interstellar Cloud 2 Million Years Ago, Altering Earth\u2019s Climate \u2013 The Brink\/Boston University \u2013 June 10, 2024<\/p>\n 2<\/sup> A possible direct exposure of the Earth to the cold dense interstellar medium 2\u20133\u2009Myr ago. \u2013 Opher, M., Loeb, A. & Peek, J.E.G. Nature Astron<\/em> (2024) \u2013 DOI: \u2013 OPEN ACCESS<\/p>\n Featured image: Zoom-in of the LxCCs as seen in 21\u2009cm data from the GALFA-HI survey<\/em><\/p>\n Monday, June 10, 2024<\/span><\/p>\n<\/div>\n<\/div>\n<\/section>\n Monday, June 3, 2024<\/span><\/p>\n<\/div>\n<\/div>\n<\/section>\n Wednesday, May 15, 2024<\/span><\/p>\n<\/div>\n<\/div>\n<\/section>\n Wednesday, May 15, 2024<\/span><\/p>\n<\/div>\n<\/div>\n<\/section>\n Thursday, April 25, 2024<\/span><\/p>\n<\/div>\n<\/div>\n<\/section>\n Wednesday, March 20, 2024<\/span><\/p>\n<\/div>\n<\/div>\n<\/section>\n\n
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