ISON-NM / L. Elenin

Comet C/2010 X1 (Elenin) is approaching the inside edge of the Main asteroid belt. Close approaches to asteroids are becoming increasingly rare, but May 21, 2011 we were able to photograph one of the most interesting approaches mentioned earlier. May 21st at 00:52 UT Comet Elenin and asteroid (74732) 1999 RQ176 passed each other at a distance of only 225,830 km, which amounts to 0.59 the average distance between the Earth and Moon. In addition, based on measurements from those same images, the size of the comet’s coma has exceeded 100,000 km, and probably in reality the coma is still larger, and we could see it on images taken with the largest telescopes. If we were on this asteroid we would have seen a simply spectacular view!

On the image at left, taken 3 hours after closest approach, you can see how close the two objects came. Asteroid 1999 RQ176 is a rather large representative of the Flora family, and has a diameter of about 2.7 km.

In a month and a half, the comet will cross the orbit of Mars reaching a heliocentric distance of 1.5 a.u., and in the opinion of well-known astronomer John Bortle, at that time the show begins.