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Epic cluster 55 EP

NGC 6531

RA 271.0560° · Dec -22.4901° · openngc

Real photograph of NGC 6531 📷 Real photo
RubinObs/NOIRLab/SLAC/NSF/DOE/AURA (CC BY 4.0)
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Score breakdown

· 8 badges
55 pts · Epic
Epic 78 pts → Anomaly
  • Messier object +12
  • Coming towards us +10
  • Toward the galactic centre +8
  • Star cluster +7
  • Distant (over 1,000 light-years) +6
  • Bright deep-sky object +6
  • Open cluster +3
  • On the zodiac +3
Total score 55

23 more points to reach Anomaly.

Badges

  • Star cluster · +7
  • Distant (over 1,000 light-years) · +6
  • Messier object · +12
  • Bright deep-sky object · +6
  • Open cluster · +3
  • Toward the galactic centre · +8
  • On the zodiac · +3
  • Coming towards us · +10

Trivia

Hard to believe

  • Messier object. One of the 110 showpieces of the Messier list — catalogued as M21.

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

  • In perspective. Far away by human standards, yet still a local address inside the Milky Way's spiral arms.
  • 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 5.9 you can see it with your own eyes from a dark site, 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.

Could we get there?

  • Verdict. Impossible with our current technology — and the next millennium of it.

Properties

constellation
Sgr
dist ly
4087.1679
dso type
OCl
mag
5.9
messier
yes
messier number
021
name
NGC 6531
radial velocity kms
-18
size arcmin
6

About NGC 6531

NGC 6531 is an epic cluster. It lies about 4,087.2 light-years from Earth, sits in the constellation Sgr and shines at apparent magnitude 5.9.

An open cluster: a few hundred stars born together out of one collapsing cloud, still drifting along in loose formation.

How to see it

Look for NGC 6531 in the constellation Sgr. At apparent magnitude 5.9, it can be glimpsed with the unaided eye under dark skies.

Like any astronomical target, NGC 6531 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 6531 is an epic cluster

NGC 6531 scores 55 points on Spacedle's rarity scale, which places it in the epic tier. Another 23 points would lift it into a rarer tier.

That score comes from 8 science badges — Star cluster, Distant (over 1,000 light-years), Messier object, Bright deep-sky object, Open cluster, Toward the galactic centre, On the zodiac 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.