Galaxy M82, Spitzer infrared image. Huge clouds of hot dust (red) surround this galaxy, also known as the Cigar galaxy as it is seen side-on from Earth as a diagonal bar (white). The dust is not visible at optical wavelengths, and the size and structure of the dust is only revealed by looking at the infrared emissions from the galaxy. It is thought that the dust has been thrown out from the galaxy by hot stars within it. M82 is about 12 million light years distant, in the constellation Ursa Major. Infrared data obtained by the orbiting Spitzer Space Telescope's IRAC sensor.