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Common cluster 21 EP

NGC 2100

RA 85.5378° · Dec -69.2118° · openngc

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Score breakdown

· 2 badges
21 pts · Common
Common 22 pts → Uncommon
  • Globular cluster +14
  • Star cluster +7
Total score 21

1 more point to reach Uncommon.

Badges

  • Star cluster · +7
  • Globular cluster · +14

Trivia

What it actually is

  • What it actually is. A globular cluster: hundreds of thousands of stars packed into a ball a few dozen light-years across, orbiting far out in the galaxy's halo.

Sense of scale

  • Sense of scale. Stand on a planet near its core and the night sky would blaze with thousands of stars brighter than Venus. There would be no true darkness.

Find it in the sky

  • How to spot it. At magnitude 9.6 you'll want a small backyard telescope, over in Dorado.
  • Southern sky only. So far south it never rises for most of the northern hemisphere. To see it you'd have to travel to Chile, South Africa or Australia.
  • 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. Globulars glow yellow-orange because they are ancient — around 12 billion years old, with every hot blue star long since burned out.

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
Dor
dso type
GCl
mag
9.6
name
NGC 2100
size arcmin
2.5

Nearby objects

About NGC 2100

NGC 2100 is a common cluster. It sits in the constellation Dor and shines at apparent magnitude 9.6.

A globular cluster: hundreds of thousands of stars packed into a ball a few dozen light-years across, orbiting far out in the galaxy's halo.

How to see it

Look for NGC 2100 in the constellation Dor. At apparent magnitude 9.6, a small backyard telescope will bring it into view.

Like any astronomical target, NGC 2100 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 2100 is a common cluster

NGC 2100 scores 21 points on Spacedle's rarity scale, which places it in the common tier. Another 1 point would lift it into a rarer tier.

That score comes from 2 science badges — Star cluster and Globular cluster — 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.