← Back to dex
Uncommon star 28 EP

HD 100221

RA 172.9526° · Dec -24.5392° · star

Loading sky survey…
🌌 View in 3D star map
Tonight’s visibility

Computing the sky for your location…

Score breakdown

· 5 badges
28 pts · Uncommon
Uncommon 34 pts → Rare
  • Deep red star +8
  • Distant (over 1,000 light-years) +6
  • Giant star +6
  • Cool red M-type star +5
  • Star +3
Total score 28

6 more points to reach Rare.

Badges

  • Star · +3
  • Distant (over 1,000 light-years) · +6
  • Cool red M-type star · +5
  • Giant star · +6
  • Deep red star · +8

Trivia

What it actually is

  • Spectral class. Its spectrum reads M1III — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.
  • Where it is in life. It is a giant. It has already exhausted its core hydrogen and swollen up enormously in response.

Sense of scale

  • In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.

Find it in the sky

  • How to spot it. At magnitude 8.1 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Crater.
  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around March — that's when to go looking.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Getting there

  • Aboard Voyager 1. ≈ 19.2 million years at Voyager 1's speed (17 km/s).

Properties

absmag
0.468
bv
1.564
constellation
Crt
dist ly
1090.8229
luminosity
56.5979
mag
8.09
name
HD 100221
spect
M1III

About HD 100221

HD 100221 is an uncommon star. It lies about 1,090.8 light-years from Earth, sits in the constellation Crt, shines at apparent magnitude 8.09 and has spectral type M1III.

Its spectrum reads M1III — an M-type red star — and M stars are the silent majority: roughly three of every four stars in the galaxy are one.

How to see it

Look for HD 100221 in the constellation Crt. At apparent magnitude 8.09, it is an easy target for binoculars.

Like any astronomical target, HD 100221 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.

Why HD 100221 is an uncommon star

HD 100221 scores 28 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 6 points would lift it into a rarer tier.

That score comes from 5 science badges — Star, Distant (over 1,000 light-years), Cool red M-type star, Giant star and Deep red 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.