About NGC 7789
NGC 7789 is a rare cluster. It sits in the constellation Cas and shines at apparent magnitude 6.7.
An open cluster: a few hundred stars born together out of one collapsing cloud, still drifting along in loose formation.
Rare cluster 35 EP
NGC 7789
RA 359.3503° · Dec 56.7083° · openngc
Score breakdown
· 6 badgesRare 50 pts → Epic
- Coming towards us +10
- Star cluster +7
- Bright deep-sky object +6
- Big on the sky +5
- Never sets (northern circumpolar) +4
- Open cluster +3
Total score 35
15 more points to reach Epic.
Badges
- Star cluster · +7
- Bright deep-sky object · +6
- Open cluster · +3
- Never sets (northern circumpolar) · +4
- Big on the sky · +5
- Coming towards us · +10
Trivia
What it actually is
- What it actually is. An open cluster: a few hundred stars born together out of one collapsing cloud, still drifting along in loose formation.
Sense of scale
- Sense of scale. Gravity is not strong enough to hold it. Within a few hundred million years these siblings will be scattered right around the galaxy.
Find it in the sky
- How to spot it. At magnitude 6.7 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. Open clusters look blue-white because they are young — their hottest, bluest stars have not had time to die yet.
How we came to know it
- The New General Catalogue. Its NGC number comes from J. L. E. Dreyer's 1888 catalogue, itself built on decades of sky sweeps by William Herschel and his sister Caroline.
Properties
- constellation
- Cas
- dso type
- OCl
- mag
- 6.7
- name
- NGC 7789
- radial velocity kms
- -54
- size arcmin
- 14.4
How to see it
Look for NGC 7789 in the constellation Cas. At apparent magnitude 6.7, it is an easy target for binoculars.
Like any astronomical target, NGC 7789 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 NGC 7789 is a rare cluster
NGC 7789 scores 35 points on Spacedle's rarity scale, which places it in the rare tier. Another 15 points would lift it into a rarer tier.
That score comes from 6 science badges — Star cluster, Bright deep-sky object, Open cluster, Never sets (northern circumpolar), Big on the sky and Coming towards us — 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.