Milky Way Mystery Solved

Astronomers have determined the cause of some particularly colorful clouds.

In the southern part of the Milky Way, clouds of crimson gas obscure giant stars that are short-lived and incredibly rare. The ESO released stunning new images of the clouds, and astronomers have confirmed how they get their brilliant red glow.

One particular nebular cloud, known as RCW 106—whose neighbors include the remnants of a supernova and filaments around a very hot star—is incredibly dense and hides massive O-type stars far away in the constellation of Norma. The intense light of the stars cause hydrogen gas in the nebular cloud to ionize, which gives off the characteristic red glow.