Last night, light from a new supernova reached astronomers on Earth. Its origin: the nearby galaxy M82, some 3.5 megaparsecs away (11.4 million light years). It is one of the closest and brightest supernovae seen from Earth since a monster exploded in 1987 just 168,000 light years away. Astronomers say that the latest supernova is of the type 1a class, and may help reveal how such supernovae form. Moreover, because these supernovae are used as cosmic measuring sticks, understanding them better may help clarify the shape of the Universe.

The supernova was bright enough to be discovered with a modest telescope in an unlikely spot: cloudy north London. On 21 January, around 7 pm, Steve Fossey, an astronomer at University College London, was taking students through a routine lesson with a 35-centimetre telescope at the University of London Observatory. Images of M82, also known as the Cigar Galaxy, appeared on their screens. Fossey noticed something unusual: a star sitting on the edge of the galaxy disc. It did not match Fossey's memory of the galaxy, nor images they looked up on the Internet. "It kind of looked odd," he says.