Spiral galaxies M81 and M82. These two galaxies passed by each other in space in the past, and the gravity of the larger M81 (upper centre) distorted the shape of M82 (lower centre). The galaxies are currently around 150,000 light years apart. M81 is seen nearly face on, and the fine structure of its spiral arms is visible. The arms contain bright patches of nebulosity, which are huge stellar nurseries illuminated by the radiation from the hot young stars within them. These two galaxies lie around 12 million light years from Earth in the constellation Ursa Major.