About NGC 2440
NGC 2440 is an uncommon nebula. It sits in the constellation Pup and shines at apparent magnitude 9.4.
A planetary nebula: the shed outer atmosphere of a dying Sun-like star, lit from within by the naked stellar core left behind.
Uncommon nebula 32 EP
NGC 2440
RA 115.4807° · Dec -18.2085° · openngc
Score breakdown
· 3 badgesUncommon 34 pts → Rare
- Planetary nebula (a dying star's shell) +12
- Its dying star is still visible +12
- Nebula +8
Total score 32
2 more points to reach Rare.
Badges
- Nebula · +8
- Planetary nebula (a dying star's shell) · +12
- 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 9.4 you'll want a small backyard telescope, over in Puppis.
- 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 January — 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
- 17.65
- constellation
- Pup
- dso type
- PN
- mag
- 9.4
- name
- NGC 2440
- radial velocity kms
- 63
- redshift
- 0.0002
- size arcmin
- 0.27
How to see it
Look for NGC 2440 in the constellation Pup. At apparent magnitude 9.4, a small backyard telescope will bring it into view.
Like any astronomical target, NGC 2440 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 2440 is an uncommon nebula
NGC 2440 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 3 science badges — Nebula, Planetary nebula (a dying star's shell) 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.