[Science] This watery planet is the best place to hunt life we’ve seen so far – AI

By Leah Crane The planet K2-18 b is located in the constellation Leo, more than 100 light years awayAlex Boersma About 110 light years away is a planet twice Earth’s size with water vapour in its atmosphere, and it may be the best place to look for alien life that we have yet seen. The detection of water there marks the first time astronomers have characterised the atmosphere of a planet of this size. Björn Benneke at the University of Montreal in Canada and his colleagues used the Hubble space telescope to observe the planet, called K2-18 b, as it passed in front of its star nine times. Benneke’s team and another group led by Angelos Tsiaras at University College London both looked at the edges of the planet as it was passing in front of the star so that light shone through the atmosphere, allowing them to analyse what it was made of. They found distinct signs of water vapour. K2-18 b is also in the habitable zone around its star, defined as the area where it could maintain liquid water on its surface without the water freezing or boiling away. “This is the only planet that we know of right now outside our solar system that is in the habitable zone, that has an atmosphere, and that has water in it, which makes it the best candidate for habitability we know of right now,” said Tsiaras in a press conference. Advertisement Read more: We could find alien life on exoplanets by looking for its glow This is the smallest planet for which we’ve been able to identify any specific molecule in its atmosphere, Tsiaras said. Planets like this one, between the size of Earth and Neptune, are common around other stars, but their atmospheres are difficult to study. “The atmosphere is like the skin of an onion, not as puffy and big as the hot giant planets, so it’s hard,” says Sara Seager at the Massachusetts Institute of Technology. “We really don’t know much about how these planets are made or what they’re made of, so this definitely a step in the right direction.” Studying the atmosphere could help us understand how these sorts of planets are formed. Is Mars habitable? Javier Martin-Torres at New Scientist Live While K2-18 b probably does have a rocky core, it is probably mostly gaseous, making it more similar to Neptune than Earth, says Laura Kreidberg at the Harvard-Smithsonian Center for Astrophysics in Massachusetts. “The jury is still out on whether a planet like this could be habitable,” she says. “If there were life there, it definitely wouldn’t be like life as we know it on Earth.” It would have to float about in the planet’s thick atmosphere, because the pressure at the surface is probably far too high for any organisms we know of to survive. Reference: arxiv.org/abs/1909.04642 Journal reference: Nature Astronomy, DOI: 10.1038/s41550-019-0878-9 More on these topics: exoplanets alien life