关于这张图
This NASA Hubble Space Telescope image of Comet (C/2012 S1) ISON was photographed on April 10, 2013, when the comet was slightly closer than Jupiter's orbit at a distance of 394 million miles from Earth. Even at that great distance the comet is already active as sunlight warms the surface and causes frozen volatiles to boil off. Astronomers used such early images to try to measure the size of the nucleus, in order to predict whether the comet would stay intact when it slingshots around the sun -- at 700,000 miles above the sun's surface -- on Nov. 28, 2013. The comet's dusty coma, or head o…
