Credit: NASA, ESA, N. Smith (U. California, Berkeley) et al., and The Hubble Heritage Team (STScI/AURA)
The ghostly Carina Nebula was discovered by Nicolas Louis de Lacaille in 1751. It is one of the largest diffuse nebulae known. It spans over 300 light years and is about 7,500 light-years away. The nebula also contains Eta Carinae a hyper gas giant. Estimates of its mass range from around 100–150 times the mass of the sun, and its luminosity is about four million times that of our own Sun.
A larger zoomable version of this picture showing the full extent of the nebula is available here
An annotated version of the larger complete nebula picture is available on wikipidia.
A complete wikipedia article on the nebula is also available.