Object Analysis

Messier 78 (M78) is a reflection nebula in the constellation Orion. It was discovered by Pierre Méchain in 1780. It is the brightest diffuse reflection nebula of a group of nebulae that belong to the Orion B molecular cloud complex.

M78 appears as a hazy patch of light illuminated by two 10th-magnitude stars, HD 38563A and HD 38563B. Unlike emission nebulae which create their own light, M78 merely reflects the blue light from these hot stars off the dust particles in the cloud.

The nebula contains 45 T Tauri variables, young stars still in the process of forming, as well as several Herbig-Haro objects—jets of gas ejected by newborn stars that collide with the surrounding medium at high speeds.