Reflection nebula M78 (also known as NGC 2068), optical image. M78 is one of the brightest reflection nebulae in the sky, and is located about 1600 light years away from Earth in the constellation Orion. It is a cloud of gas and dust about three light years across, reflecting the light of nearby stars. Because blue light is scattered more than red by the dust particles, the nebula appears blue. The dark lanes across the bright regions are dense dust clouds obscuring the light. Orion contains large, diffuse nebulous regions of star birth and ionised gas clouds, which appear as a red background.