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Uncommon star 33 EP

HD 218195

RA 346.3039° · Dec 58.2415° · star

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Score breakdown

· 3 badges
33 pts · Uncommon
Uncommon 34 pts → Rare
  • Blazing O-type star +26
  • Never sets (northern circumpolar) +4
  • Star +3
Total score 33

1 more point to reach Rare.

Badges

  • Star · +3
  • Never sets (northern circumpolar) · +4
  • Blazing O-type star · +26

Trivia

Hard to believe

  • True brightness. It pours out about 3.8 million times as much light as the Sun. It only looks ordinary because it is so far away.

What it actually is

  • Spectral class. Its spectrum reads O8 — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.

Find it in the sky

  • How to spot it. At magnitude 8.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Cassiopeia.
  • Northern sky. It rides the northern half of the sky — an easier target the further north you are.
  • Best time of year. It stands highest in the middle of the night around September — that's when to go looking.

Its true colour

  • Its true colour. Measured through blue and visual filters it comes out brilliant white (B−V 0.2) — hotter and whiter than the Sun, the colour of Sirius or Vega.
  • Why no green stars. No star ever looks green: a surface hot enough to peak in green also floods out plenty of red and blue, and your eye blends the mixture back to white.

By the numbers

  • Surface temperature. Its colour puts the surface at roughly 7800 K, against the Sun's 5778 K.

Properties

absmag
-11.63
bv
0.249
constellation
Cas
luminosity
3908408.9579
mag
8.37
name
HD 218195
spect
O8

About HD 218195

HD 218195 is an uncommon star. It sits in the constellation Cas, shines at apparent magnitude 8.37 and has spectral type O8.

Its spectrum reads O8 — an O-type star — the hottest, rarest main class there is. Fewer than one star in a million is an O, and none of them lasts long.

How to see it

Look for HD 218195 in the constellation Cas. At apparent magnitude 8.37, it is an easy target for binoculars.

Like any astronomical target, HD 218195 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 218195 is an uncommon star

HD 218195 scores 33 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 1 point would lift it into a rarer tier.

That score comes from 3 science badges — Star, Never sets (northern circumpolar) and Blazing O-type 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.