Exoplanet K2-18b is a super-Earth that's twice the size of our planet, with eight times the mass. It's also wet, or at least the skies around it are. Researchers found records of water vapor when they took data captured byin 2016 and 2017 and ran it through an open-source algorithm they developed to analyze distant planets. They published their findings Wednesday in the journal Nature.
Water vapor has been found in the atmospheres of other planets, but this is the first time such moisture has been spotted on a planet in the habitable zone of its star, where temperatures could
More data was needed to determine what kind of cloud coverage the planet has, how much water is present in the atmosphere, and if the stuff is actually forming large bodies of water on the planet's surface like here on Earth.
"It's entirely possible this is a water world," said co-author Giovanna Tinetti, a professor of astrophysics at University College London. But she cautioned that it was too early to confirm the presence of some sort of surface ocean.
It is estimated that temperatures on the planet could be between about 100 degrees Fahrenheit (minus 73 Celsius) and 150 Fahrenheit (66 Celsius).
"However, this planet is not another Earth," Angelos Tsiaras, a research associate at UCL, told reporters Tuesday . "It is orbiting what we call a red dwarf star … in this environment the space weather is more hostile than here on Earth."
also called M-dwarf stars, are smaller, cooler and dimmer than our sun. They're also known for frequently releasing powerful solar flares that could . Fortunately, K2-18, which is 110 light years from Earth, is not as prone to spouting off as other M-dwarf stars.
"This one in particular is not very active at all," Ingo Waldmann, a lecturer in extrasolar planets at UCL and the paper's co-author, told me. "We've not seen any flaring."
The analysis of starlight passing through the planet's atmosphere also showed hydrogen and helium. Future studies could determine if other molecules closely related to life as we know it, like nitrogen and methane, are also present.
The researchers are hopeful that the upcomingwhich will be significantly more powerful than Hubble, may provide an even clearer view of what's happening on distant exoplanets. If conditions are right, you may even want to add the K2-18b to an interstellar travel itinerary in the far-off future.
"Our discovery makes K2-18b one of the most interesting targets for future study," Tinetti said.
Originally published Sept. 11, 10 a.m. PT.