Thursday, October 25, 2007

Check Out Comet 17P/Holmes

If you have an opportunity, please check out Comet 17P/Holmes. The comet nucleus (core) appears to be having an outburst of activity. It is possible that the nucleus may be breaking up, but this is not certain. In the last 48 hours the comet has greatly increased in brightness, now visible at magnitude 2.5! Recent reports suggest the coma (the atmosphere of the comet) is expanding and taking on a lopsided shape, perhaps the beginnings of a significant tail.

The coma appears yellow, probably the color of the reflected sunlight. The edges of the comet may appear green which likely signifies an atmosphere rich in diatomic carbon and cyanogen, typical components of greenish comets.

The comet appears just to the East of the constellation Perseus. If you are in the Tampa Bay area, Perseus will rise in the North East about 7PM and be completely above the horizon just after 8PM. Comet 17P/Holmes should be visible roughly to the East (left) of Epsilon Persei (the thigh of Perseus) which shines at magnitude 2.89. In fact, you might mistake the comet for Epsilon Persei because of its brightness.

Comet 17P/Holmes was discovered by British astronomer Edwin Holmes (1842-1919) on November 6, 1892 while conducting regular observations of the Andromeda Galaxy (M31). The orbital specifics for the comet are as follows: Aphelion distance, 5.2004 AU; Perihelion distance, 2.1655 AU; Semi-major axis, 3.618 AU ; Eccentricity, 0.4120; Orbital period, 7.0679 a (Julian years, lasting 365.25 days); Inclination, 19.1877°; Last perihelion, May 4, 2007; Next perihelion (predicted), March 27, 2014.

For more details, check out these Web pages:

Space Weather Home Page:

Space Weather Sky Chart:

Sky and Telescope Article:

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