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Uncommon star 29 EP

25The UMa

RA 143.2157° · Dec 51.6773° · star

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Score breakdown

· 6 badges
29 pts · Uncommon
Uncommon 34 pts → Rare
  • Naked-eye visible +8
  • Binary star +6
  • Subgiant (leaving the main sequence) +5
  • Never sets (northern circumpolar) +4
  • Star +3
  • Yellow-white F-type star +3
Total score 29

5 more points to reach Rare.

Badges

  • Star · +3
  • Naked-eye visible · +8
  • Binary star · +6
  • Never sets (northern circumpolar) · +4
  • Yellow-white F-type star · +3
  • Subgiant (leaving the main sequence) · +5

Trivia

What makes it special

  • Not one star but two. It is a binary: two stars orbiting a shared centre of mass. More than half of all the 'stars' you can see are actually multiple systems.

What it actually is

  • Spectral class. Its spectrum reads F6IV — an F-type star — a little hotter, whiter and shorter-lived than the Sun.
  • Where it is in life. It is a subgiant, caught in the act of leaving the main sequence as the hydrogen in its core runs out.

Sense of scale

  • In perspective. Inside our stellar backyard: every radio broadcast humanity has ever made has already swept past it.

Find it in the sky

  • How to spot it. At magnitude 3.2 you can see it with your own eyes from a dark site, over in Ursa Major.
  • 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 February — that's when to go looking.

Could we get there?

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

Properties

absmag
2.522
binary
yes
bv
0.475
constellation
UMa
dist ly
43.9622
luminosity
8.5349
mag
3.17
name
25The UMa
spect
F6IV

About 25The UMa

25The UMa is an uncommon star. It lies about 44 light-years from Earth, sits in the constellation UMa, shines at apparent magnitude 3.17 and has spectral type F6IV.

It is a binary: two stars orbiting a shared centre of mass. More than half of all the 'stars' you can see are actually multiple systems.

How to see it

Look for 25The UMa in the constellation UMa. At apparent magnitude 3.17, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, 25The UMa 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 25The UMa is an uncommon star

25The UMa scores 29 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 5 points would lift it into a rarer tier.

That score comes from 6 science badges — Star, Naked-eye visible, Binary star, Never sets (northern circumpolar), Yellow-white F-type star and Subgiant (leaving the main sequence) — 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.