Uncommon star 30 EP

HD 9722

RA 24.2105° · Dec 61.8161° · star

Loading sky survey…

🌌 View in 3D star map

Tonight’s visibility

Computing the sky for your location…

Score breakdown

· 4 badges

30 pts · Uncommon

Uncommon 34 pts → Rare

Supergiant +18
White A-type star +5
Never sets (northern circumpolar) +4
Star +3

Total score 30

4 more points to reach Rare.

Badges

Star · +3
Never sets (northern circumpolar) · +4
White A-type star · +5
Supergiant · +18

Trivia

Hard to believe

True brightness. It pours out about 4.5 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 A0Iab — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.
Where it is in life. It is a supergiant. Drop it where the Sun is and its surface would engulf the inner planets.

Find it in the sky

How to spot it. At magnitude 8.2 it is just past naked-eye reach — ordinary binoculars will pull it in, 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 October — that's when to go looking.

Its true colour

Its true colour. Measured through blue and visual filters it comes out orange (B−V 0.8) — cooler than the Sun, and the kind of star that burns steadily for tens of billions of years.
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: -11.81
bv: 0.818
constellation: Cas
luminosity: 4613175.7456
mag: 8.19
name: HD 9722
spect: A0Iab

Nearby objects

About HD 9722

HD 9722 is an uncommon star. It sits in the constellation Cas, shines at apparent magnitude 8.19 and has spectral type A0Iab.

Its spectrum reads A0Iab — an A-type star: white-hot, typically about twice the Sun's mass, and the class most of the sky's famous bright stars belong to.

How to see it

Look for HD 9722 in the constellation Cas. At apparent magnitude 8.19, it is an easy target for binoculars.

Like any astronomical target, HD 9722 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 9722 is an uncommon star

HD 9722 scores 30 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 4 points would lift it into a rarer tier.

That score comes from 4 science badges — Star, Never sets (northern circumpolar), White A-type star and Supergiant — 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.