IC 423 and IC 426 reflection nebulae, optical image. IC 423 is at lower right; IC 426 at upper left. These nebulae are reflection nebulae in the constellation Orion. Reflection nebulae are clouds of dust and gas that do not emit their own light, but reflect the light of bright nearby stars. They appear blue because blue light is scattered more than red. At the edges of the frame are bright regions surrounding two of the three stars of Orion's belt. At the bottom lies Alnilam (Epsilon Orionis), the central star of the belt, and to the right is Mintaka (Delta Orionis).