About IC 4591
IC 4591 is an uncommon nebula. It sits in the constellation Sco.
An H II region: a cloud of hydrogen being ionised by the ultraviolet flood from hot young stars inside it. Every one is a star factory caught mid-production.
Uncommon nebula 30 EP
IC 4591
RA 243.0757° · Dec -27.9277° · openngc
Score breakdown
· 4 badgesUncommon 34 pts → Rare
- Star-forming region +14
- Nebula +8
- Big on the sky +5
- On the zodiac +3
Total score 30
4 more points to reach Rare.
Badges
- Nebula · +8
- Star-forming region · +14
- On the zodiac · +3
- Big on the sky · +5
Trivia
What it actually is
- What it actually is. An H II region: a cloud of hydrogen being ionised by the ultraviolet flood from hot young stars inside it. Every one is a star factory caught mid-production.
Find it in the sky
- Where to look. You'll find it in the constellation Scorpius.
- 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 May — that's when to go looking.
Its true colour
- Its true colour. That signature crimson is hydrogen-alpha at 656 nanometres — electrons falling back onto protons, one photon at a time.
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
- Sco
- dso type
- HII
- name
- IC 4591
- size arcmin
- 12
How to see it
Look for IC 4591 in the constellation Sco.
Like any astronomical target, IC 4591 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 4591 is an uncommon nebula
IC 4591 scores 30 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 4 points would lift it into a rarer tier.
That score comes from 4 science badges — Nebula, Star-forming region, On the zodiac and Big on the sky — 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.