This stunning space wallpaper is a NASA Hubble Space Telescope image of Comet C/2012 S1 (ISON) when the comet was slightly closer than Jupiter's orbit at a distance of 386 million miles (621 km) from the sun. This is a contrast-enhanced photo produced from the Hubble images of Comet ISON to reveal the subtle structure in the inner coma of the comet. In this computer-processed view, the Hubble image has been divided by a computer model coma that decreases in brightness proportionally to the distance from the nucleus, as expected for a comet that is producing dust uniformly over its surface. ISON's coma shows enhanced dust particle release on the sunward-facing side of the comet's nucleus, the small, solid body at the core of the comet. This image was taken April 19, 2013.
(Image: © NASA/ESA,/J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team)