Graphic: Finbar Sheehy

With Orion and the winter constellations at their best, it may be hard to drag our gaze away from the S sky on February evenings. Jupiter, too, is conspicuous in Gemini where it lies to the left of the Moon on Monday, 10 February. We know all too well, though, it is not always clear in the optimum direction and it may be better to turn our attention elsewhere.

This is just what happened to a group of University College London students and their tutor on 21 January when, with the weather closing in, they swung their telescope towards a contracting area of clear sky in the NE. Their target was the galaxy M82 and what they discovered is one of the closest and brightest supernovae for several years.

M82 is one of a pair of galaxies in northern Ursa Major. Its sister, M81, lies 0.6° to its S and is a beautiful spiral galaxy visible through binoculars at mag 7.0. M82 appears smaller and fainter, being closer to mag 8.5 and a stiff test for binoculars although easy through a telescope. Both galaxies are thought to lie almost 12 million light years away and make up one of the showpiece sights in our northern sky.

To locate them, use our chart and begin with the Plough which stands handle down as it climbs in the NE this evening. A line through Merak to Dubhe, the Pointers, extends due N towards Polaris. If we take another line from Phecda across to Dubhe and extend it for a similar distance we reach an area near the mag 4.6 star 24 Ursae Majoris which is enlarged in the upper-right of the chart.

Like its companion, M82 is a spiral at heart though this fact was only confirmed nine years ago. Seen almost edge-on, its spiral arms are hidden by dusty filaments and bright clumps that mark where stars are forming rapidly. Indeed, M82 is a so-called starburst galaxy in which new stars are blazing forth and dying as supernovae in a maelstrom of activity that may have been triggered by a close encounter with M81 while dinosaurs ruled on the Earth. All this leads to M82 being the brightest galaxy in the sky if viewed through infrared eyes, and the most powerful source of radio waves in Ursa Major.

The new supernova, dubbed SN 2014J, lies almost 1 arcmin WSW of the galaxy's centre. After peaking near mag 10.5 at the beginning of this month, it is now likely to be fading but is still an easy target through telescopes. Spectroscopic studies show it to be a Type Ia supernova, in which material piling onto a white dwarf star in a binary system triggers the catastrophic destruction of the star.

It is interesting that a supernova of similar brightness erupted in M81 in 1993 and that the only other comparable supernova since then occurred in another galaxy in Ursa Major, M101, in 2011.