Saturn Nebula

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Saturn Nebula
MUSE image of the Saturn Nebula.jpg
Observation data: J2000.0 epoch
Right ascension 21h 04m 10.877s[2]
Declination−11° 21′ 48.25″[2]
Distance2000-4000 ly
(See article) ly
Apparent magnitude (V)8.0[3]
Apparent dimensions (V)41″ × 35″[2]
Physical characteristics
Radius0.2 to 0.4 ly
Absolute magnitude (V)2.5 to 1
Notable features-
DesignationsNGC 7009,[2] Caldwell 55
See also: Lists of nebulae

The Saturn Nebula or NGC 7009 is a planetary nebula in the constellation Aquarius. It appears as a greenish-yellowish hue in a small amateur telescope, it was discovered by William Herschel on September 7, 1782, using a telescope of his own design in the garden at his home in Datchet, England, and was one of his earliest discoveries in his sky survey. The nebula was originally a low-mass star that ejected its layers into space, forming the nebula; the central star is now a bright white dwarf star of apparent magnitude 11.5. The Saturn Nebula gets its name from its superficial resemblance to the planet Saturn with its rings nearly edge-on to the observer, it was so named by Lord Rosse in the 1840s, when telescopes had improved to the point that its Saturn-like shape could be discerned. William Henry Smyth said that the Saturn Nebula is one of Struve's nine "Rare Celestial Objects."

The Saturn Nebula is a complex planetary nebula and contains many morphological and kinematic sub-systems in three dimensions, it includes a halo, jet-like streams, multiple shells, ansae ("handles"), and small-scale filaments and knots. The ansae are expanding non-radially from the central star.[4] Although the ansae are most prominent in the Saturn Nebula, they are also visible in other planetary nebulae, including NGC 3242, NGC 6543 and NGC 2371-2.

The distance of the Saturn Nebula is not known precisely. Sabbadin et al. 2004 estimates the distance to be 5,200 light-years (1.6 kpc). In 1963 O'Dell estimated it to be 3,900 light-years (1.2 kpc), which gives an approximate diameter of 0.5 light years for the object as a whole.

The central star, a very hot bluish dwarf with a temperature of 55,000 K, from which the nebula is believed to originate, has an absolute magnitude of +1.5, which equates to a luminosity of about 20 solar luminosities and a visual magnitude of 11.5. This strong ultraviolet irradiation from the central star creates the characteristic fluorescent green tint of the nebula via the radiation of doubly ionized oxygen; the object overall has a visual magnitude of 8 and a radial velocity of 28 miles per second towards the Earth.

The nebula is 1 degree west of the star Nu Aquarii; the central portion measures 25″ × 17″, while the outer shell extends to 41″ × 35″. The object is on many "best of" observing lists.[5][6][7]



  1. ^ "The Strange Structures of the Saturn Nebula". Retrieved 27 September 2017.
  2. ^ a b c d "NAME Saturn Nebula". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2006-12-26.
  3. ^ "Messier Online Astronomical Database". Saturn Nebula. Retrieved 2012-08-28.
  4. ^ Steffen, W.; Espíndola, M.; Martínez, S.; Koning, N. (October 2009). "The 3D velocity structure of the planetary nebula NGC 7009". Revista Mexicana de Astronomía y Astrofísica. 45: 143–54. arXiv:0905.2148. Bibcode:2009RMxAA..45..143S. NGC 7009 is a planetary nebula with several morphological and kinematical sub-systems with multiple shells, a halo, jet-like streams, ansae and small-scale filaments and knots.
  5. ^ SAC 110 best NGC object list
  6. ^ RASC's Finest N.G.C. Objects Objects
  7. ^ The Caldwell Catalog (#55)


External links[edit]

Coordinates: Sky map 21h 04m 10.877s, −11° 21′ 48.25″