Planet K218b is in the news:
“Water vapor exists everywhere in the universe,” says astronomer Björn Benneke of the University of Montreal, who reported the potential discovery in a paper posted September 10 at arXiv.org. “But it’s not so easy to make liquid water; you need the right pressure and the right temperature. That’s what makes this planet special.”
The exoplanet-hunting Kepler space telescope discovered K2 18b in 2015. The planet orbits a dim red dwarf star about 110 light-years away, and is bigger and heavier than Earth: about 2.5 times Earth’s radius and about eight times its mass.Lisa Grossman, “This may be the first known exoplanet with rain and clouds of water droplets” at ScienceNews
Most exoplanets, we are told, fall into this size range and it is not yet known if it has a rocky surface, considered important for life.
It is in the Habitable Zone though:
If confirmed by further studies, this will be the only exoplanet known to have both water in its atmosphere and temperatures that could sustain liquid water on a rocky surface. Liquid water would only be possible if the planet turns out to be terrestrial in nature, rather than resembling a small version of Neptune.
Given the high level of activity of its red dwarf star, K2-18b may be more hostile to life as we know it than Earth, as it is likely to be exposed to more high-energy radiation. The planet, discovered by NASA’s Kepler Space Telescope in 2015, also has a mass eight times greater than Earth’s. That means the surface gravity on this planet would be significantly higher than on our planet.
“NASA’s Hubble Finds Water Vapor on Habitable-Zone Exoplanet for 1st Time” at NASA
Water is not always decisive though:
In the past two decades, astronomy has undergone a revolution. Since the first detection of exoplanets in 1992, scientists have cataloged thousands of alien worlds orbiting distant stars—some of which show signs of having atmospheres.
For a handful of these planets, astronomers have even spotted signs of atmospheric water vapor. But previously, worlds with confirmed water were uninhabitable for life as we know it. For instance, in 2018, NASA announced the discovery of water vapor in the atmosphere of WASP-39b, an enormous Saturn-size planet where the day side reaches a scorching 1,430 degrees Fahrenheit.Michael Greshko, “Water found on a potentially life-friendly alien planet” at National Geopraphic
People would love to believe it is rain:
In a press release, Dr. Waldmann said, “With so many new super-Earths expected to be found over the next couple of decades, it is likely that this is the first discovery of many potentially habitable planets. This is not only because super-Earths like K2-18b are the most common planets in our Milky Way, but also because red dwarfs — stars smaller than our Sun — are the most common stars.”
The planet has a very short year. It takes only 33 days to complete one orbit. The researchers think that K2-18b is either a rocky planet, or an icy one. If it’s icy, it may have a large quantity of water in its interior. But these are just preliminary results.Evan Gough, “Water Discovered in the Atmosphere of an Exoplanet in the Habitable zone. It Might Be Rain” at Universe Today
Maybe. We’ll keep you posted. Here’s the paper. (public access) It would be great to find another planet capable of supporting hope, not hype.
See also: Tales of an invented god
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