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Comets are balls of ice and rock, so called ‘dirty snowballs’, that come from the far reaches of the solar system. Comet NEOWISE has a nucleus around 5km (3 miles) in diameter with a tail that has two parts as is typical for comets – a white tail made of fragments of the comet itself and a blue tail, made of ionised gas blown back by the solar wind.

Photographer: Chris Davis