Messier 78 or M78 (also designated NGC 2068) is a diffuse nebula in the constellation Orion. It has an apparent visual magnitude of 8.3 and its angular diameter is 8x6 arc-minutes. M78 lies at an estimated distance of 1600 light years. The Equinox 2000 coordinates are RA= 5h 46.7m, Dec= +00° 03´ which makes M78 best seen during the winter. The Messier Winter Star Chart shows the position of all Messier objects visible during that season.

The image above shows the uncropped view of M78 through the Takahashi E-180 Astrograph (North is up). A 2x enlargement of this image appears to the right.

This diffuse nebula was discovered by P. Méchain in 1780. M78 is part of the much larger Orion Molecular Cloud Complex. This immense region also includes the Great Orion Nebula M42, M43 and the Horsehead Nebula located south of Zeta Orionis (Alnitak), the easternmost star in the Belt of Orion. According to Stoyan et al. (2010), the distance of M78 is 1300 light years and its diameter is 3 light years.

For more information, see the Messier Catalog as well as specific entries for M78 in Wikipedia and SEDS.

Messier's Description of M78

December 17, 1780
`Cluster of stars, with much nebulosity in Orion and on the same parallel as the star Delta in the belt, which has served to determine its position; the cluster follows [is east of] the star on the hour wire at 3d 41', and the cluster is above [north of] the star by 27'7". M. Méchain had seen this cluster at the beginning of 1780, and reported: "On the left side of Orion [Glyn Jones has, erroneously, the right]; 2 to 3 minutes in diameter, one can see two fairly bright nuclei, surrounded by nebulosity".' (diam. 3')

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