) is an emission nebula
that can be found in the southern constellations Vela
. Hard to distinguish, it is believed to be the greatly expanded (and still expanding) remains of a supernova
that took place about a million years ago. The nebula is out of sight from most of the United States
It is named after its discoverer, the Australian astronomer Colin Stanley Gum (1924-1960). Gum had published his findings in 1955 in a work called A study of diffuse southern H-alpha nebulae.