Rare star 45 EP

HIP 117707

RA 358.0814° · Dec 62.1185° · star

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Score breakdown

· 4 badges

45 pts · Rare

Rare 50 pts → Epic

Blazing O-type star +26
Bright giant +12
Never sets (northern circumpolar) +4
Star +3

Total score 45

5 more points to reach Epic.

Badges

Star · +3
Never sets (northern circumpolar) · +4
Blazing O-type star · +26
Bright giant · +12

Trivia

Hard to believe

True brightness. It pours out about 1.6 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 O9.5II — 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.
Where it is in life. It is a bright giant, well on its way to the largest stars there are.

Find it in the sky

How to spot it. At magnitude 9.3 you'll want a small backyard telescope, over in Cassiopeia.
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 September — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out yellow-white (B−V 0.3) — a shade brighter and crisper than our own Sun.
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.

Properties

absmag: -10.7
bv: 0.313
constellation: Cas
luminosity: 1659586.9074
mag: 9.3
name: HIP 117707
spect: O9.5II

Nearby objects

About HIP 117707

HIP 117707 is a rare star. It sits in the constellation Cas, shines at apparent magnitude 9.3 and has spectral type O9.5II.

Its spectrum reads O9.5II — 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 HIP 117707 in the constellation Cas. At apparent magnitude 9.3, a small backyard telescope will bring it into view.

Like any astronomical target, HIP 117707 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 HIP 117707 is a rare star

HIP 117707 scores 45 points on Spacedle's rarity scale, which places it in the rare tier. Another 5 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Never sets (northern circumpolar), Blazing O-type star and Bright giant — 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.