Archive for July 15th, 2011

“Countdown to 500 comets. Comet Elenin”. By Alan Hale

A. Hale

This has, undoubtedly, been one of the most eagerly-awaited comets in recent years. It was discovered back on December 10, 2010 by Leonid Elenin, an astronomer in Lyubertsy, Russia (affiliated with the Keldysh Institute of Applied Mathematics in Moscow), who is an accomplished observer of comets and who has in fact made several recoveries of expected periodic comets within the fairly recent past; this is his first comet discovery. Leonid was observing remotely with a 45-cm (18-inch) telescope (equipped with a CCD) at the International Scientific Optical Network observatory in New Mexico (not too far from where I live, incidentally), and at the time of his discovery the comet was a rather faint object between 19th and 20th magnitudes and was located 4.2 AU from the sun.

The first calculated orbits for Comet Elenin suggested it would remain a distant object, however it soon became clear that it was traveling on a remarkably low-inclination orbit (1.8 degrees) that would carry it quite close to both the sun and the earth. Furthermore, the geometry for forward scattering of sunlight — and thus an accompanying brightness enhancement — is quite favorable around that time. All this has led to a realization that Comet Elenin possesses at least the potential to become a relatively bright object — conceivably even a “Great Comet” — for a brief period of time around perihelion passage and its closest approach to Earth.

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July 2011
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