6 May 2011

 

Comet Elenin: will it be spectacular?

 

Of all the comets that reach naked eye visibility, the most spectacular are the long period comets, coming from the remotest parts of our solar system, well beyond the orbit of the most distant planet. One of the reasons that these long period comets can be spectacular is that their relatively infrequent passages close to the Sun allow them to retain a large amount of volatile material near the surface, whereas the short period comets suffer more frequent episodes of activity which deplete their reserves.
The discovery of new long period comets therefore usually receives quite some attention, and Elenin is no exception. The comet, designated C/2010 X1, was observed for the first time remotely by Leonid Elenin (Russian astronomer from Lyubertsy) on 10th December 2010 with one of the International Scientific Optical Network telescopes.
When discovered, the comet was at a distance of 647 million km from Earth with a magnitude of about 20. In the above illustration (released by NASA) the trajectory and position of Elenin is indicated for the 4th May, when the comet was 274 million km away. This distance will decrease to 35 million km at closest approach to the Earth on 16th October.
In the meantime the comet will continue to be imaged, and it looks like this comet will be among the most photographed, given that over 1300 CCD images have already been made (by comparison about 1000 images were collected for Hyakutake, C/1996 B2).
As to whether Elenin will be spectacular, there are some doubts. Don Yeomans, head of NASA's Spaceguard program at the Jet Propulsion Laboratory, is sceptical, but an unexpected outburst, such as seen with comets 17P/Holmes and C/2006 P1 McNaught, can't be excluded. The latest estimate of the perihelion magnitude of the comet, by Artem Novichonok, is magnitude 4, but for a best case scenario it could reach magnitude zero. Therefore, the comet could remain visible to the naked eye until the beginning of November. Only time will tell...

 

by Michele Ferrara & Marcel Clemens

credit: JPL/NASA