Comet ISON (C/2012 S1), as observed on 10 April 2013 by the Hubble Space Telescope (HST). This comet was discovered on 21 September 2012 by the International Scientific Optical Network (ISON). Here, it is 621 million kilometres from the Sun, and 634 million kilometres from the Earth. It will pass close to the Sun in November 2013, increasing greatly in brightness. The area visible here is over 80,000 kilometres across, and was obtained by the HST's Wide Field Camera 3 (WFC3) instrument. The cometary nucleus itself is only a few kilometres across. For an enhanced view of the comet's coma, see C015/9817.