The Eskimo Nebula (NGC 2392), also known as the Clown-faced Nebula, Lion Nebula, or Caldwell 39, is a bipolar double-shell

planetary nebula A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives. The term "planetary nebula" is a misnomer because they are unrelated to ...

(PN). It was discovered by

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, natural satellite, moons, comets and galaxy, g ...

William Herschel Frederick William Herschel (; german: Friedrich Wilhelm Herschel; 15 November 1738 – 25 August 1822) was a German-born British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline H ...

in 1787. The formation resembles a person's head surrounded by a

parka A parka or anorak is a type of coat with a hood, often lined with fur or faux fur. This kind of garment is a staple of Inuit clothing, traditionally made from caribou or seal skin, for hunting and kayaking in the frigid Arctic. Some Inuit ano ...

hood. It is surrounded by gas that composed the outer layers of a Sun-like star. The visible inner filaments are ejected by a strong wind of particles from the central star. The outer disk contains unusual, light-year-long filaments. NGC 2392 lies about 6500 light-years away, and is visible with a small

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

in the constellation of

Gemini Gemini may refer to: Space * Gemini (constellation), one of the constellations of the zodiac ** Gemini in Chinese astronomy * Project Gemini, the second U.S. crewed spaceflight program * Gemini Observatory, consisting of telescopes in the Northern ...

. At the center of NGC 2392, there is an

O-type star An O-type star is a hot, blue-white star of spectral type O in the Yerkes classification system employed by astronomers. They have temperatures in excess of 30,000 kelvin (K). Stars of this type have strong absorption lines of ionised helium, st ...

with a

spectral type In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...

of O(H)6f.

Historic data

The nebula was discovered by

on January 17, 1787, in

Slough Slough () is a town and unparished area in the unitary authority of the same name in Berkshire, England, bordering west London. It lies in the Thames Valley, west of central London and north-east of Reading, at the intersection of the M4 ...

, England. He described it as "A star 9th magnitude with a pretty bright middle, nebulosity equally dispersed all around. A very remarkable phenomenon." NGC 2392 WH IV-45 is included in the

Astronomical League The Astronomical League is an umbrella organization of amateur astronomy societies. Currently their membership consists of over 280 organizations across the United States, along with a number of Members-at-Large, Patrons, and Supporting members. ...

's Herschel 400 observing program.

Location

:NGC 2392 is located just east of δ Geminorum, just south the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic again ...

Naming controversy

On 11 August 2020, the

IAU Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN),

NASA/IPAC Extragalactic Database The NASA/IPAC Extragalactic Database (NED) is an online astronomical database for astronomers that collates and cross-correlates astronomical information on extragalactic objects (galaxies, quasars, radio, x-ray and infrared sources, etc.). NED was ...

(NED), and

SIMBAD Astronomical Database SIMBAD (the Set of Identifications, Measurements and Bibliography for Astronomical Data) is an astronomical database of objects beyond the Solar System. It is maintained by the Centre de données astronomiques de Strasbourg (CDS), France. SIMBA ...

(CDS) discontinued use of three nicknames that were perceived as offensive - "

Eskimo Eskimo () is an exonym used to refer to two closely related Indigenous peoples: the Inuit (including the Alaska Native Iñupiat, the Greenlandic Inuit, and the Canadian Inuit) and the Yupik peoples, Yupik (or Siberian Yupik, Yuit) of eastern Si ...

Nebula", "

Clown A clown is a person who performs comedy and arts in a state of open-mindedness using physical comedy, typically while wearing distinct makeup or costuming and reversing folkway-norms. History The most ancient clowns have been found in ...

Face Nebula", and "Clownface Nebula" - and strongly recommended the nebula be referred to by its NGC designation in further publications.

Notes

Radius = distance × sin(angular size / 2) = ≥2900 ly * sin(48″ / 2) = ≥0.34 ly
10.1 apparent magnitude - 5 * (log₁₀(≥880 pc distance) - 1) = ≤0.4 absolute magnitude

References

External links

*
APOD (2003-12-07)
– NGC 2392
Eskimo Nebula
Lowell Observatory

University of Maryland Astronomy Department
A Kinematic Determination of the Structure of the Double Ring Planetary Nebula NGC 2392, the Eskimo
Astrophysical Journal v.362, p.226 October 1990
A Cat's Eye view of the Eskimo from Saturn
Maria-Teresa Garc ́ıa-D ́ıaz, Jose-Alberto L ́opez, Wofgang Steffen,Michael G. Richer and Hortensia Riesgo, 2011 {{DEFAULTSORT:Eskimo Nebula Planetary nebulae Gemini (constellation) 2392 17870117 039b