About IC 5117
IC 5117 is a rare nebula. It sits in the constellation Cyg and shines at apparent magnitude 11.5.
A planetary nebula: the shed outer atmosphere of a dying Sun-like star, lit from within by the naked stellar core left behind.
Rare nebula 42 EP
IC 5117
RA 323.1290° · Dec 44.5966° · openngc
Score breakdown
· 4 badgesRare 50 pts → Epic
- Planetary nebula (a dying star's shell) +12
- Its dying star is still visible +12
- Coming towards us +10
- Nebula +8
Total score 42
8 more points to reach Epic.
Badges
- Nebula · +8
- Planetary nebula (a dying star's shell) · +12
- Coming towards us · +10
- Its dying star is still visible · +12
Trivia
What it actually is
- What it actually is. A planetary nebula: the shed outer atmosphere of a dying Sun-like star, lit from within by the naked stellar core left behind.
Find it in the sky
- How to spot it. At magnitude 11.5 you'll want a small backyard telescope, over in Cygnus.
- 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 August — that's when to go looking.
Its true colour
- Its true colour. Its teal-green comes from doubly-ionised oxygen at 501 nanometres, and its red from hydrogen at 656 — colours no ordinary object on Earth produces.
What's in a name
- A misleading name. 'Planetary nebula' is a 240-year-old mistake. William Herschel coined it in the 1780s because these round greenish discs resembled the planet Uranus he had just discovered. There are no planets involved whatsoever.
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
- central star mag
- 16.7
- constellation
- Cyg
- dso type
- PN
- mag
- 11.5
- name
- IC 5117
- radial velocity kms
- -26
- size arcmin
- 0.02
How to see it
Look for IC 5117 in the constellation Cyg. At apparent magnitude 11.5, a small backyard telescope will bring it into view.
Like any astronomical target, IC 5117 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 5117 is a rare nebula
IC 5117 scores 42 points on Spacedle's rarity scale, which places it in the rare tier. Another 8 points would lift it into a rarer tier.
That score comes from 4 science badges — Nebula, Planetary nebula (a dying star's shell), Coming towards us and Its dying star is still visible — 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.