Comet ISON Heads Towards Mars

Perihelion of Comet ISON Perihelion is due to occur on 28 November 2013. ISON’s size is only estimated at present but is thought to be around a few miles in diameter. This will become more apparent in the next few months as the comet continues its approach during 2013. Astronomers who have been processing data from NASA’s Swift satellite, estimate the comet to be around 3 miles in diameter. They have reached this conclusion by observing the amount of ice and dust emitted from ISON’s surface as it falls through space toward the Sun