爱斯基摩星云

爱斯基摩星云（Eskimo Nebula，NGC 2392），亦称阿尼脸星云，是位于双子座的一个行星状星云，距离地球约2,900光年远，由英国天文学家威廉·赫歇尔在1787年发现的；使用小型望远镜就可以看见。

由于地面上观察受大气影响，影像不甚清晰之下，它像是被带头罩雪衣的敞篷围拢的正面头象，也就是因为影像不太清晰，爱斯基摩头像更甚“相似”（略带想像空间）。2000年哈伯太空望远镜对这个星云作高解像照相观测，呈现人们尚未能充分了解的复杂气体结构。

星云前身是一颗类似太阳质量的恒星，约在10,000年前，气体才在它的外围开始笼罩。其内部的细丝是由中心恒星吹出的星风中的微粒组成的，外壳中有异常的长达一光年的橙色丝线。

The Eskimo Nebula is a bipolar, double-shell planetary nebula (PN) in the northern constellation of Gemini. Alternatively, it is known as NGC 2392, Clown Face Nebula, Lion Nebula, or Caldwell 39. This feature was discovered by German-British astronomer William Herschel in 1787. NGC 2392 lies about 6,500 light-years away, and is visible with a small telescope. The formation resembles a person's head surrounded by a parka hood. It is surrounded by gas that composed the ejected outer layers of a Sun-like star. The visible inner filaments are ejected by a strong wind of particles from the central …

At the center of NGC 2392, there is an O-type star (designated HD 59088) with a spectral type of O(H)6f.

Historic data

The nebula was discovered by William Herschel on January 17, 1787, in Slough, 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's Herschel 400 observing program.

On 9 January 1982 it was occulted by the Moon during a Total Lunar Eclipse (the January 1982 lunar eclipse) over Greenland, the Arctic, the extreme northeast of North America, the northern half of Europe, North and Northeast Asia. This event was seen by several observers in England. The occultation during total eclipse will happen again during the January 2066 lunar eclipse over the northern half of Asia and the Northwest Pacific.

Naming controversy

On 11 August 2020, the IAU Working Group on Star Names (WGSN), NASA/IPAC Extragalactic Database (NED), and SIMBAD Astronomical Database (CDS) discontinued use of nicknames that were perceived as offensive which included "Eskimo Nebula", and strongly recommended the nebula be referred to by its NGC designation in further publications.