Comet 17P/Holmes

Comet 17P/Holmes

Comet 17P/Holmes on November 25, 2007

On October 24, 2007, Comet 17P/Holmes surprised everyone by suddenly increasing in brightness. The comet ejected a massive amount of dust particles that expanded into a 1.4 million kilometer diameter coma by November 9. The dust particles were expelled away from the nucleus at a speed of 1,100 miles-per-hour. As a result of this sudden outburst, the comet became a million times brighter over the course of a few days. It was visible to the naked eye, and a striking target for binoculars. Visually, the comet appeared as a fuzzy ball with no discernable structure. However, this image taken with a 3-inch refractor telescope shows a tail extending to the left of the comet nucleus.

Comet 17P/Holmes is a periodic comet that completes an orbit around the Sun every 6.88 years. It was an old inactive comet. However, comets are unpredictable. This comet had two previous outbursts in November 1892 and January 1893, but those events were not as dramatic as the unprecedented activity observed in 2007. Comet 17P/Holmes is believed to have originated in the Kuiper Belt, and was probably deflected into its present orbit by Jupiter's gravity sometime within the last few thousand years. The solid nucleus of the comet is estimated to be only 3.6 kilometers (about 2.2 miles) in diameter. Comet 17P/Holmes was discovered on November 6, 1892, by a British amateur astronomer in London England using a 320mm (almost 13-inch) reflector telescope.

Comets sometimes break apart into fragments when they near the Sun, as Comet 73P/Schwassmann-Wachmann 3 did in April 2006.

This image was published on the website for It is an RGB color CCD image taken with an ST-8XE CCD and a Takahashi FS-78 refractor. The image was taken from my backyard in Scottsdale, Arizona.

Constellation: Perseus
RA: 03h 17m 50s Dec: +49d 38' 42"
November 25, 2007 at 1002 UT
Image by Sid Leach
Scottsdale, Arizona

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