About IC 2157
IC 2157 is a trash cluster. It sits in the constellation Gem and shines at apparent magnitude 8.4.
An open cluster: a few hundred stars born together out of one collapsing cloud, still drifting along in loose formation.
Trash cluster 13 EP
IC 2157
RA 91.1983° · Dec 24.0710° · openngc
Score breakdown
· 3 badgesTrash 15 pts → Common
- Star cluster +7
- Open cluster +3
- On the zodiac +3
Total score 13
2 more points to reach Common.
Badges
- Star cluster · +7
- Open cluster · +3
- On the zodiac · +3
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 8.4 it is just past naked-eye reach — ordinary binoculars will pull it in, over in Gemini.
- 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 December — 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 Index Catalogue. The IC was the 1895 and 1908 supplement to the NGC — the first catalogue in history to be filled largely with objects found on photographic plates rather than by eye.
Properties
- constellation
- Gem
- dso type
- OCl
- mag
- 8.4
- name
- IC 2157
- size arcmin
- 2.7
How to see it
Look for IC 2157 in the constellation Gem. At apparent magnitude 8.4, it is an easy target for binoculars.
Like any astronomical target, IC 2157 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 IC 2157 is a trash cluster
IC 2157 scores 13 points on Spacedle's rarity scale, which places it in the trash tier. Another 2 points would lift it into a rarer tier.
That score comes from 3 science badges — Star cluster, Open cluster and On the zodiac — 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.