Astronomers have made a very interesting discovery: For the first time, water vapor has been detected in the atmosphere of an exoplanet that lies in the habitable zone for its star.
The detection looks pretty good to me, and this has some potentially exciting implications, but first things first:
NO, THIS DOES NOT MEAN THE PLANET IS EITHER EARTH-LIKE OR HABITABLE.
Clear enough? The quick-and-dirty is that this planet is more like Neptune than Earth, a massive world with a thick atmosphere. When this news broke yesterday I saw a lot (a lot) of misinformation out there, mostly just confusion or errors in understanding the science coupled with breathless headlines designed to get clicks.
Here’s the actual deal.
The star K2-18, a red dwarf known to host one planet and likely at least two (both are invisible on this scale). Credit: SIMBAD/SDSS
The star K2-18 is a red dwarf, smaller, cooler, and much fainter than the Sun. It's about 120 light years away, which is close as stars go (which isn't too surprising; it's hard to observe red dwarfs much farther away than that because they're so dim).
There is at least one planet orbiting it, called K2-18b (some observations ...