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Common star 18 EP

HD 204100

RA 320.8552° · Dec 65.0340° · star

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Score breakdown

· 4 badges
18 pts · Common
Common 22 pts → Uncommon
  • Hot blue B-type star +6
  • Blue-white star +5
  • Never sets (northern circumpolar) +4
  • Star +3
Total score 18

4 more points to reach Uncommon.

Badges

  • Star · +3
  • Never sets (northern circumpolar) · +4
  • Hot blue B-type star · +6
  • Blue-white star · +5

Trivia

What it actually is

  • Spectral class. Its spectrum reads B9 — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

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 7.3 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Cepheus.
  • Never sets. So far north that from Britain, Canada or northern Europe it never dips below the horizon — it is up every clear night of the year.
  • Best time of year. It stands highest in the middle of the night around August — that's when to go looking.

Could we get there?

  • Verdict. Hopelessly far for any craft humanity can build today.

Getting there

  • Aboard Voyager 1. ≈ 15.4 million years at Voyager 1's speed (17 km/s).
  • Fastest probe ever. ≈ 1.4 million years even at the Parker Solar Probe's 192 km/s.

Properties

absmag
0.167
bv
-0.038
constellation
Cep
dist ly
879.1268
luminosity
74.6793
mag
7.32
name
HD 204100
spect
B9

About HD 204100

HD 204100 is a common star. It lies about 879.1 light-years from Earth, sits in the constellation Cep, shines at apparent magnitude 7.32 and has spectral type B9.

Its spectrum reads B9 — a blue-white B-type star, with a surface tens of thousands of degrees hot and a life measured in tens of millions of years.

How to see it

Look for HD 204100 in the constellation Cep. At apparent magnitude 7.32, it is an easy target for binoculars.

Like any astronomical target, HD 204100 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 204100 is a common star

HD 204100 scores 18 points on Spacedle's rarity scale, which places it in the common tier. Another 4 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Never sets (northern circumpolar), Hot blue B-type star and Blue-white 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.