M82 is located in the northern hemisphere near the constellation Ursa Major at a distance of just over 10 million light years. A close encounter with the giant spiral galaxy M81 some 300 million years ago set off the starburst event that we now see in the centre of M82. Huge quantities of gas were funnelled into the centre by gravitational forces. Eventually when this gas settled, large numbers of dense star clusters were formed which produce the burst of star formation we see today. We believe the starburst and the resulting superwind are around 10 million years old. Today, M81 and M82 are safely separated by 120,000 thousand light years.