The celestial visitor was reported to be up to magnitude 4.5 on Tuesday night, 24 October, around five times brighter than was predicted.
Comet Swan is now the brightest comet in the night sky for several years but it is not known how long the flare-up will last. The reason is believed to be an eruption within the comet’s frozen head, or nucleus, which released a vast cloud of gas as it was warmed by the Sun.
At magnitude 4.5, the comet will be fairly easy to spot in a dark sky, providing you know just where to look. It is currently passing between Corona Borealis and Hercules and visible showing a short tail high in the western sky as soon as it gets dark.
Its head is shining emerald green – a sign that it contains the poisonous gas cyanogen. Spaceweather.com reports that the delicate tail can be followed for the apparent width of three full moons across the sky before fading away. A map of the sky to help find the comet is at this page on the society’s website.
Amateur astronomer Pete Lawrence, of Selsey, West Sussex, took the beautiful photo shown here of Comet Swan on Tuesday night following its outburst.