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

planetary nebula A planetary nebula 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 planets. The ...

(PN). It was discovered by

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

William Herschel Frederick William Herschel ( ; ; 15 November 1738 – 25 August 1822) was a German-British astronomer and composer. He frequently collaborated with his younger sister and fellow astronomer Caroline Herschel. Born in the Electorate of Hanover ...

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

parka A parka, like the related anorak, is a type of coat (clothing), coat with a hood (headgear), hood, that may be lining (sewing), lined with fur or fake fur. Parkas and anoraks are staples of Inuit clothing, traditionally made from Reindeer, cari ...

hood. It is surrounded by gas that composed the outer layers of a

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

-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 (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

in the constellation of

Gemini Gemini most often refers to: * Gemini (constellation), one of the constellations of the zodiac * Gemini (astrology), an astrological sign Gemini may also refer to: Science and technology Space * Gemini in Chinese astronomy, the Gemini constellat ...

. At the center of NGC 2392, there is an

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

(designated HD 59088) with a

spectral type In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

of O(H)6f.

Historic data

The nebula was discovered by

on January 17, 1787, in

Slough Slough () is a town in Berkshire, England, in the Thames Valley, west of central London and north-east of Reading, at the intersection of the M4, M40 and M25 motorways. It is part of the historic county of Buckinghamshire. In 2021, the ...

, 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 330 organizations across the United States, along with a number of Members-at-Large, Patrons, and Supporting members. ...

's Herschel 400 observing program. On 9 January 1982 it was occulted by the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

during a

Total Lunar Eclipse A lunar eclipse is an astronomical event that occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. Such an alignment occurs during an eclipse season, approximately every six months, during the full moon pha ...

(the

January 1982 lunar eclipse A total lunar eclipse occurred at the Moon’s ascending node of orbit on Saturday, January 9, 1982, with an umbral magnitude of 1.3310. A lunar eclipse occurs when the Moon moves into the Earth's shadow, causing the Moon to be darkened. A total ...

) over

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

, the

Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

, the extreme northeast of

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, the northern half of

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and

Northeast Asia Northeast Asia or Northeastern Asia is a geographical Subregion#Asia, subregion of Asia. Its northeastern landmass and islands are bounded by the Pacific Ocean, North Pacific Ocean. The term Northeast Asia was popularized during the 1930s by Ame ...

. This event was seen by several observers in

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

. The occultation during total eclipse will happen again during the

January 2066 lunar eclipse January is the first month of the year in the Julian and Gregorian calendars. Its length is 31 days. The first day of the month is known as New Year's Day. It is, on average, the coldest month of the year within most of the Northern Hemispher ...

over the northern half of Asia and the Northwest Pacific.

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. SIMB ...

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

Eskimo ''Eskimo'' () is a controversial Endonym and exonym, exonym that refers to two closely related Indigenous peoples: Inuit (including the Alaska Native Iñupiat, the Canadian Inuit, and the Greenlandic Inuit) and the Yupik peoples, Yupik (or Sibe ...

Nebula", "

Clown A clown is a person who performs physical comedy and arts in an Improvisational theatre#Comedy, open-ended fashion, typically while wearing distinct cosmetics, makeup or costume, costuming and reversing social norm, folkway-norms. The art of ...

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) NGC objects 17870117 039b

Historic data

Naming controversy

See also

Notes

References

External links