Scientists have announced the discovery of water vapor and, likely, clouds and rain, on a far-away planet. K2-18 b, the potentially habitable world, is now considered one of the best known candidates to host alien life.
The far-off planet (it’s about 110 light-years away) was discovered in 2015 by NASA’s Kepler space telescope. The alien world is about two times the size of Earth and eight times as massive. K2-18 b orbits a red dwarf star in the “habitable zone” — the range of distances where liquid water could be stable on a world’s surface.
University College London’s Angelos Tsiaras told Space.com that, when taken together, the evidence of water and its distance from its star, makes K2-18 b “the best target for habitability that we know right now.” As always, though, there’s plenty of reason to pause. There’s still a lot scientists don’t know about the world — for example, the atmosphere could contain anywhere between 0.01 percent and 50 percent water, and nobody is quite sure what the surface is like, either.
This finding has sparked a host of new questions regarding what exactly this exoplanet and its atmosphere are like. According to this study, there are three equally likely atmospheric models for the exoplanet.
The first possibility described by these researchers is a cloud-free atmosphere that contains only water and hydrogen-helium. The second possibility is a cloud-free atmosphere that has water, hydrogen-helium and molecular nitrogen. Third, the researchers think that this planet’s atmosphere could be cloudy with water and hydrogen-helium.
“These are, statistically, equally likely, given the data,” Ingo Waldmann, one of the authors of this new study, said in the news conference. The “answer is probably somewhere in between those,” he added.
A lot of these questions will be difficult to answer, but researchers are hopeful that they might be able to chip away at some of them following the launch of NASA’s James Webb Space Telescope in 2021.