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Uncommon cluster 32 EP

NGC 6638

RA 277.7344° · Dec -25.4964° · openngc

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Score breakdown

· 4 badges
32 pts · Uncommon
Uncommon 34 pts → Rare
  • Globular cluster +14
  • Toward the galactic centre +8
  • Star cluster +7
  • On the zodiac +3
Total score 32

2 more points to reach Rare.

Badges

  • Star cluster · +7
  • Globular cluster · +14
  • Toward the galactic centre · +8
  • On the zodiac · +3

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 9.7 you'll want a small backyard telescope, over in Sagittarius.
  • Southern sky. It rides the southern half of the sky — an easier target the further south you are.
  • Best time of year. It stands highest in the middle of the night around June — 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
Sgr
dso type
GCl
mag
9.68
name
NGC 6638
radial velocity kms
9
redshift
0
size arcmin
4.2

Nearby objects

About NGC 6638

NGC 6638 is an uncommon cluster. It sits in the constellation Sgr and shines at apparent magnitude 9.68.

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 6638 in the constellation Sgr. At apparent magnitude 9.68, a small backyard telescope will bring it into view.

Like any astronomical target, NGC 6638 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 6638 is an uncommon cluster

NGC 6638 scores 32 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 2 points would lift it into a rarer tier.

That score comes from 4 science badges — Star cluster, Globular cluster, Toward the galactic centre 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.