Last night, light from a supernova explosion 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 the 1987 observation of a supernova just 168,000 light years away. Astronomers say that the latest supernova is of the type Ia class, and may help reveal how such supernovae form. Moreover, because these supernovae are used to calibrate distances in space, 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, or images they looked up on the Internet. "It kind of looked odd," he says.
As the sky grew cloudy, Fossey's students checked their telescope for instrumental errors, and also confirmed that the object was not an asteroid. Fossey fired up another small telescope at the observatory and confirmed the object's location before clouds closed in at 7:45 pm. Then he emailed colleagues at California Institute of Technology in Pasadena.