Illustration showing Mars and Comet Siding Spring encounter

This illustration — created for a NASA press release — combines data from the NASA/ESA Hubble Space Telescope of Comet Siding Spring and separate Hubble data of Mars.

On 19 October 2014 — the day that the images of both Mars and the comet were taken — at 20:28 CEST, the comet passed within only 140 000 kilometres of the red planet — roughly a third the distance between the Earth and the Moon. At that time the comet and Mars were almost 250 million kilometres from Earth. This flyby of Comet Siding Spring is the closest encounter of a comet with a planet ever observed!

The background starfield, which has been added to this image, is synthesised from ground-based telescope data