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Common variable star 15 EP

HD 21231

RA 51.2889° · Dec -12.3552° · star

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Score breakdown

· 2 badges
15 pts · Common
Common 24 pts → Uncommon
  • Distant (>1000 ly) +10
  • Variable star +5
Total score 15

9 more points to reach Uncommon.

Badges

  • Variable star · +5
  • Distant (>1000 ly) · +10

Trivia

Could we get there?

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

Getting there

  • Aboard Voyager 1. ≈ 18.3 million years at Voyager 1's speed (17 km/s).
  • Fastest probe ever. ≈ 1.6 million years even at the Parker Solar Probe's 192 km/s.
  • At 10% light speed. ≈ 10.4 thousand years in a starship at a tenth of light speed.
  • Distance. 1039 light-years from Earth.

Look-back time

  • Look-back time. The light you'd see left around the year 987.

Saying hello

  • Say hello. A radio message and its reply would take 2077 years round-trip.

Properties

absmag
1.215
bv
1.544
constellation
Eri
dist ly
1038.7133
mag
8.73
name
HD 21231
spect
M3/M4III

About HD 21231

HD 21231 is a common variable star. It lies about 1,038.7 light-years from Earth, sits in the constellation Eri, shines at apparent magnitude 8.73 and has spectral type M3/M4III.

HD 21231 is a common variable star worth 15 points across 2 science badges. Explore its facts, badges and place on the sky map, then add it to your dex on Spacedle.

How to see it

Look for HD 21231 in the constellation Eri. At apparent magnitude 8.73, it is an easy target for binoculars.

Like any astronomical target, HD 21231 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 21231 is a common variable star

HD 21231 scores 15 points on Spacedle's rarity scale, which places it in the common tier. Another 9 points would lift it into a rarer tier.

That score comes from 2 science badges — Variable star and Distant (>1000 ly) — 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.

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Sky imagery and survey data courtesy of Aladin Lite & CDS, Strasbourg. Object data from the NASA Exoplanet Archive, JPL Small-Body Database, and the ATNF Pulsar Catalogue.