M82 is a so-called starburst galaxy, about 12 million light-years away. The high rate of star production, about 10 times that of other galaxies, has apparently been triggered by gravitational (tidal) interactions with the nearby M81. At least one of these events is thought to have caused a flood of gas into the galaxy's core, resulting in many "super star clusters", of which almost 200 have been observed (with the Hubble Space Telescope) in M82. There are many supernovae amongst these new stars (about 1 every 10 years) and these are causing the "superwind" of energised hydrogen which is flowing out from each side (red in the image).