| Comet C/2010 X1 (Elenin) is a long-period comet discovered by Russian amateur astronomer Leonid Elenin on December 10, 2010, remotely, using the International Scientific Optical Network's robotic observatory near Mayhill, New Mexico, USA At the time of discovery Elenin had an apparent magnitude of 19.5, making it about 150000 times fainter than the naked eye magnitude of 6.5. The discoverer, Leonid Elenin, estimates that the comet nucleus is 3--4 km in diameter. C/2010 X1 to have a heliocentric orbital period of 600000 years. Brightness In April 2011, the comet was around magnitude 15 (roughly the brightness of Pluto), and the coma (expanding tenuous dust atmosphere) of the comet was estimated to be about 80000 km in diameter. As of 21 May 2011 the coma exceeded 100000 km, and as of August 2011 the coma exceeded 200000 km. Between May 22 and June 4 visual magnitude estimates varied from 13.1 to 13.8. As of late July 2011, visual magnitude estimates of the comet were approaching 10. Even at a magnitude of 10, the comet is about 25 times fainter than the naked eye can see under a completely dark sky. C/2010 X1 will come to perihelion (closest approach to the Sun) on 10 September 2011 at a distance of 0.4824 AU (72170000 km; 44840000 mi). On 16 October 2011, the comet will make its closest approach to the Earth at a distance of 0.2338 AU (34980000 km; 21730000 mi) with a relative velocity of 86000 km/h. The Minor Planet Center ephemeris shows this relatively bright comet ... |
