RA 52.1954° · Dec -59.9767° · star
3 more points to reach Rare.
HD 21900 is an uncommon variable star. It sits in the constellation Ret, shines at apparent magnitude 9.34 and has spectral type M3III.
Its spectrum reads M3III — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
Look for HD 21900 in the constellation Ret. At apparent magnitude 9.34, a small backyard telescope will bring it into view.
Like any astronomical target, HD 21900 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.
HD 21900 scores 31 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 3 points would lift it into a rarer tier.
That score comes from 6 science badges — Variable star, Cool red M-type star, Giant star, Deep red star, Gently variable and A named variable star — 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.