On June 30, when this image was taken, comet C/2001 A2 (LINEAR) had passed perihelion and was moving away from us and the sun. Prior to that time, the comet had been visible only from the southern hemisphere as it brightened to a 3rd magnitude object. The comet became visible from the northernm hemisphere as a morning object, and was easily located with binoculars.
This is another of a long list of comets discovered by the Lincoln Laboratory Near Earth Asteroid Research project. Although they are actually looking for asteroids, that automated minor-planet survey discovers quite a few comets as a by-product of the search for asteroids.
Comets are essentially dirty snow-balls, and are believed to contain material left over from the formation of the solar system. Comets spend most of their time far from the inner solar system in a region beyond the plant Pluto known as the Oort Cloud, orbiting at a distance of about half a light year from the Sun. When a comet is out in the Oort Cloud, it is much too far away to be seen from Earth. Comets are only discovered when the comet's orbit brings it into the inner solar system. When that happens, the heat from the Sun causes outer frozen layers of the comet to "melt" or sublimate, and the comet grows a tail. In this image, you can see comet's tail exrtending away from the sun.
This is an unguided composite CCD image consisting of sixteen 60-second exposures taken with an ST-8E using a 6-inch Takahashi FCT-150 refractor telescope at prime focus operating at f7. The trailed stars were removed from the final image. The image was taken from a dark sky location North of Phoenix, Arizona.
Constellation: Cetus
RA:00h 47m Dec:-06d 00'.
June 30, 2001 at 0930 U.T.
Image by Sid Leach
Phoenix, Arizona.
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