Planet: K2-131b (aka EPIC 228732031b)
Discovered by: Fei Dei et al. using NASA's Kepler telescope
Date: October 19, 2017
Key Facts: This discovery is a super Earth two times Earth's size, that orbits a yellow Sun-like star. But don't get too excited about life on this planet– temperatures there are hot enough to vaporize metal. This sizzling-hot world takes only nine hours to orbit its star, a journey which takes Mercury 88 days. K2-131b is likely to be a lifeless inferno, where the planet’s sun never sets on the dayside.
What's new: A super Earth isn't super because it's twice as cool as Earth– it's super because it's twice the size. This planet is about 6.5 times more massive than Earth, and almost certainly rocky like our own planet. From the surface, its sun would appear 41 degrees wide in the sky– that's 80 times the width of the full moon! The Kepler space telescope found this super Earth (and many others) during its ongoing K2 mission.
See details and check the official NASA planet count at the NASA Exoplanet Archive
Paper: "The discovery and mass measurement of a new ultra-short-period planet: EPIC 228732031b"