This is a picture of the Carina Nebula, also known as NGC 3372. It is a huge nebula spanning over 300 light years. The dark shapes you can see in this image are actually clouds of molecular gas and dust so thick they appear opaque. In comparison, however, these clouds are much less dense than the Earth’s atmosphere. The nebula lies about 7,500 light-years away in the constellation of Carina.
Images credit: NASA, ESA, N. Smith (U. California, Berkeley) et al., and The Hubble Heritage Team (STScI/AURA).