Located in the constellation Orion, the M42 Great Orion Nebula is the brightest emission and reflection nebula in the northern night sky. Although the nebula is about 1,500 light-years away from the Earth, we can still find it from the winter night sky.

We took the attached image using a lens of 400mm focal length in Sai King during early January this year. The colors of the nebula are distinctive. Hot stars in the nebula emit ultraviolet radiation that ionise the surrounding hydrogen atoms. The excited hydrogen atoms release its energy by emitting red light. Some interstellar materials in the nebula reflect the blue light emitted from the stars themselves directly.

Observed with a pair of binoculars, the Great Orion Nebula looks like a hazy white cloud. It is located under the Orion's belt formed by three evenly spaced stars in a nearly straight line. Let's try to find it during stargazing in the winter time.