Messier 78

Messier 78 (also known as M78 or NGC 2068) is a reflection nebula in the constellation Orion. It is the brightest diffuse reflection nebula in a group that includes NGC 2064, NGC 2067, and NGC 2071, all part of the Orion B molecular cloud complex. Located approximately 1,350 light-years from Earth,^[2] M78 is visible in small telescopes as a hazy patch illuminated by two B-type stars, HD 38563 A and HD 38563 B, of 10th and 11th magnitude.^[4]

Messier 78

Reflection nebula
Image of Messier 78 captured using the Wide Field Imager camera on the MPG/ESO 2.2-metre telescope at the La Silla Observatory.
Observation data: J2000.0 epoch
Right ascension	05h 46m 46.7s[1]
Declination	+00° 00′ 50″[1]
Distance	1,350 ly (415 pc)[2] ly
Apparent magnitude (V)	8.3[3]
Apparent dimensions (V)	8′ × 6′[3]
Constellation	Orion
Physical characteristics
Radius	5 ly
Notable features	Part of the Orion complex
Designations	Ced 55u, DG 80, IRAS 05442-0000, [KPS2012] MWSC 0664, NGC 2068[1]
See also: Lists of nebulae

Discovery

Discovered by Pierre Méchain in 1780, M78 was included in Charles Messier's catalog of comet-like objects that same year.^[5]

Structure and composition

The nebula's dust cloud reflects light from its two central stars, making it visible. Infrared observations reveal an embedded star cluster^[2] and a hierarchy of gas clumps with core masses ranging from 0.3 M_☉ to 5 M_☉.^[6] M78 hosts:

• 45 T Tauri stars (young stellar objects still forming).^[7]
• 17 Herbig–Haro objects (jets emitted by nascent stars).^[8]

Observations

On May 23, 2024, the European Space Agency released a high-resolution image of M78 from the Euclid mission, revealing hundreds of thousands of previously unseen objects, including substellar bodies.^[9]

Gallery

• 
  VISTA image of Messier 78.
• 
  Spitzer image of Messier 78.
• 
  Euclid image of star-forming region Messier 78

See also

• List of Messier objects