Exoplanet K2-18b is a super Earth that is twice the size of our planet, with eight times the mass. It's also wet, or at least the sky is around. Researchers found evidence of water vapor when they took data captured by NASA's Hubble Space Telescope
Water vapor is found in the atmosphere of other planets, but this is the first time such moisture has been spotted on a planet in its star's habitable zone, where temperatures can be tolerated, if not downright pleasant.
More data is needed to determine what cloud covers the planet, how much water is present in the atmosphere, and whether things actually form large bodies of water on the planet's surface, as here on Earth.
"It's quite possible that this is a water world," says co-author Giovanna Tinetti, a professor of astrophysics at University College London. But she warned that it was too early to confirm the existence of any kind of surface ocean.
It is estimated that planet temperatures can be between about minus 100 degrees Fahrenheit (minus 73 Celsius) and 150 Fahrenheit (66 Celsius). This is a large scope, of course, but it is not too far from the conditions we see here on Earth.
"However, this planet is not a second Earth," Andreas Ciras, a research associate at UCL, told reporters Tuesday, "It is in orbit of what we call a red dwarf star … in this space environment time is more hostile than here on Earth.
also called M-dwarf stars are smaller, cooler and darker than our sun. They are also known for often emitting powerful solar flares that can . Fortunately, K2-18, located 110 light-years from Earth, is not as prone to scattering as other M-dwarf stars.
"This one in particular is not very active at all," Ingo Waldmann, a professor of extrasolar planets at UCL and co-author of the newspaper, told me. "We have not seen any burns."
Analysis of the starlight passing through the planet's atmosphere also revealed hydrogen and helium. Future studies could determine whether other molecules closely related to life, as we know it, such as nitrogen and methane, are also present.
Researchers hope that the forthcoming James Webb Telescope which will be significantly more powerful than Hubble, can provide an even clearer view of what is happening on distant exoplanets. If the conditions are right, you may even want to add the K2-18b to an interstellar travel route in the distant future.
"Our discovery makes K2-18b one of the most interesting targets for future study," Tinetti said.
Originally published on September 11, 10:00 am PT.