The Orion complex (sometimes called the Orion molecular cloud complex) is a huge star-forming area in the constellation of Orion.^[1]

It is a large group of bright nebulae, dark clouds, and young star clusters. The cloud is between 1,500 and 1,600 light-years away and is hundreds of light-years across. Several parts of the nebula can be seen through binoculars and small telescopes. Some parts (such as the Orion nebula) are visible to the naked eye.

The nebula is important because of its sheer size. It is also one of the most active regions of stellar formation that can be seen in the night sky. In it are protoplanetary discs and many very young stars. The nebula is very bright in the infrared wavelengths due to the heat-intensive processes involved in star formation. The complex contains dark nebulae, emission nebulae, reflection nebulae, and HII regions.

The following is a list of notable nebulae in the larger nebula complex:

• The Orion nebula, also known as M42
• M43, which is part of the Orion Nebula
• IC 434, which contains the Horsehead Nebula
• The Horsehead nebula
• Barnard's Loop
• M78, a reflection nebula
• NGC 1999
• NGC 2175
  • NGC 2174
• Various Orion molecular clouds
• Flame nebula (NGC 2024)

Also the Orion OB1 Association is part of this complex. This is a group of several dozen hot giant stars of spectral types O and B. These are blue and blue-white stars.

• Orion Cloud Complex
• SEDS website
• Clickable table of Messier Objects Archived 2014-10-20 at the Wayback Machine
• Orion images Archived 2014-04-07 at the Wayback Machine