CG4 glows menacingly 1,300 light years from Earth in this image from ESO’s Very Large Telescope. CG4 is a sub-type of nebula known as a Bok globule — a very compact, very dense, very cold nebula — the smallest type of dark nebula, only a light-year or two across. Inside that region is a mass that can roughly vary between 2 and 100 times the mass of our sun. credit: ESQ