RA 340.3038° · Dec -14.4893° · exoplanet
5 more points to reach Rare.
K2-21 b is an uncommon exoplanet. It lies about 272.8 light-years from Earth, shines at apparent magnitude 12.85, has spectral type M0.0 and has an equilibrium temperature near 500 K.
It orbits closer to its star than Mercury does to the Sun, completing a lap in less time than Mercury takes.
At apparent magnitude 12.85, it takes a larger telescope or a long-exposure image to capture.
Like any astronomical target, K2-21 b is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. The visibility panel above works out tonight's viewing window for your saved location.
K2-21 b scores 29 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 5 points would lift it into a rarer tier.
That score comes from 4 science badges — Confirmed exoplanet, Super-Earth, Tidally locked and Multi-planet system — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.