• The Orion Molecular Cloud Complex (or, simply, the Orion Complex) is a large group of bright nebulae, dark clouds, and young stars in the Orion constellation.
• Several parts of the nebula can be observed through binoculars and small telescopes, and some parts (such as the Orion Nebula) are visible to the naked eye.
• The nebula is important because of its sheer size, as it spreads several degrees from Orion’s Belt to his sword.
• It is also one of the most active regions of stellar formation visible in the night sky, and is home to both protoplanetary discs and very young stars.
• The nebula is bright in infrared wavelengths due to the heat-intensive processes involved in the stellar formation, though the complex contains dark nebulae, emission nebulae, reflection nebulae, and H II regions.
• The presence of ripples on the surface of Orion’s Molecular Cloud have been discovered recently.
• The ripples result from the expansion of the nebulae gas over pre-existing molecular gas.

Source: Wiki