Key facts
- Right ascension
- 11 50 17.7
- Declination
- −57 ° 10 ′ 56.9 ″
- Distance
- 4 900 ly
- Apparent dimensions v
- 8 to 10 arcsec
- Constellation
- Centaurus
- Radius
- 0.095-0.12 ly
- Designations
- He2-74 / Hen 2-74 / Sa2-81 / PK 294+4.1 / PN G294.6+04.7 / , ESO 170-1
via Wikipedia infobox
Wikidata facts
- Distance from Earth
- 1639
- Image
- Planetary nebula NGC 3918.jpg
Show 9 more facts
- catalog code
- Gaia DR2 5342260406474812416
- Commons category
- NGC 3918
- time of discovery or invention
- 1834-04-03
- apparent magnitude
- 13.4238
- right ascension
- 177.57405141999910
- declination
- -57.18251642646010
- radial velocity
- -16.4
- right ascension component of proper motion
- -3.228
- declination component of proper motion
- 2.718
Sources (1)
via Wikidata · CC0
~1 min read
Article
NGC 3918 is a bright planetary nebula in the constellation Centaurus, nicknamed the "Blue Planetary" or "The Southerner". It is the brightest of the far southern planetary nebulae. This nebula was discovered by Sir John Herschel in March 1834 and is easily visible through small telescopes. The round or even slightly oval diameter is telescopically between 8 and 10 arcsec, though deep images extends this to about 19 or 20 arcsec. More surprising is the beautiful rich blue colour that looks much like the coloured images of Neptune taken by Voyager 2 in 1989.
Spectroscopy reveals NGC 3918 is approaching us at 17±3.0 kilometres per second, while the nebulosity is expanding at around 24 kilometres per second. The central star is 14.6 visible light magnitude, and remains invisible to optical observers, as it is obscured by the sheer brightness of the surrounding nebula.