About NGC 6644
NGC 6644 is a rare nebula. It sits in the constellation Sgr and shines at apparent magnitude 10.7.
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 43 EP
NGC 6644
RA 278.1447° · Dec -25.1294° · openngc
Score breakdown
· 5 badgesRare 50 pts → Epic
- Planetary nebula (a dying star's shell) +12
- Its dying star is still visible +12
- Nebula +8
- Toward the galactic centre +8
- On the zodiac +3
Total score 43
7 more points to reach Epic.
Badges
- Nebula · +8
- Planetary nebula (a dying star's shell) · +12
- Toward the galactic centre · +8
- On the zodiac · +3
- 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 10.7 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. 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 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
- central star mag
- 15.6
- constellation
- Sgr
- dso type
- PN
- mag
- 10.7
- name
- NGC 6644
- radial velocity kms
- 194
- redshift
- 0.0006
- size arcmin
- 0.04
Nearby objects
How to see it
Look for NGC 6644 in the constellation Sgr. At apparent magnitude 10.7, a small backyard telescope will bring it into view.
Like any astronomical target, NGC 6644 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 6644 is a rare nebula
NGC 6644 scores 43 points on Spacedle's rarity scale, which places it in the rare tier. Another 7 points would lift it into a rarer tier.
That score comes from 5 science badges — Nebula, Planetary nebula (a dying star's shell), Toward the galactic centre, On the zodiac 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.