The Cigar Galaxy is a remarkable and peculiar galaxy in Ursa Major. It was discovered along with its partner M81 by Johann Bode and both galaxies are often known as Bode’s Nebulae. M82 is five times brighter than the whole Milky Way. It is interacting gravitationally with its neighbour, Bode’s Galaxy M81.

Until 2005, M82 was classified as an irregular galaxy, but then two spiral arms were discovered in the near infrared. Our view of the galaxy is almost edge-on and it is receding from us at about 200 km/s. In 2005, the Hubble Space Telescope revealed 197 young massive star clusters in the starburst core. The average mass of each of these clusters is 200,000 solar masses (4 x 10³⁵ kg), thus contributing about 80% of the total mass of the galaxy (50,000 million solar masses or 1 x 10⁴¹ kg). Hence the starburst core is a very energetic and high-density environment. Throughout the galaxy's centre young stars are being born ten times faster than they are inside our entire Milky Way Galaxy. A unique “superwind” flowing out of these clusters appears to be fuelled by supernovae that occur about once every ten years.

The most recent of these, SN 2014J, was discovered in January 2014 by Dr Steve Fossey and four students at University College London. Fossey was running a routine telescope demonstration and cloud forced him to choose M82 as his target. On inspection of the first image he noticed a new bright point of light which was soon confirmed as the brightest supernova in recent decades. Fossey also noticed a flashing X-ray source. Much further investigation has revealed a surprisingly powerful pulsar M82X-2, the brightest pulsar yet known, and a rare intermediate mass black hole M82X-11 - its mass is about 400 times that of the Sun (8 x 10³² kg).