SpaceWeather update: Giant Comet bigger than the sun

Posted: Nov 16, 2007 05:04 am EST

( "University of Hawaii astronomers have measured the diameter of Comet 17P/Holmes: 1.4 million kilometers. This makes the exploding comet bigger than the sun and now the largest object in the solar system, " reports.

"Not surprisingly, the comet is visible to the naked eye; with only a backyard telescope you can watch its gigantic debris cloud expand from night to night. Nov. 19th is an especially good night to look: Comet Holmes will glide by Mirfak, the brightest star in the constellation Perseus, and appear to swallow it."

Note: The sun remains by far the most massive object in the solar system. Comet 17P/Holmes' diaphanous atmosphere of dust and gas, which is what the astronomers measured, contains less mass than a typical asteroid. In spite of its great size, Comet Holmes is a lightweight that won't be deflecting the orbits of planets or causing any other such catastrophes.


Comet 17P/Holmes shocked astronomers on Oct. 24, 2007, with a spectacular eruption. In less than 24 hours, the 17th magnitude comet brightened by a factor of nearly a million, becoming a naked-eye object in the evening sky. Look for a golden 2.5th magnitude fuzzball in the constellation Perseus after sunset. Image Sebastian Voltmer, Spicheren, France Nov. 12, 2007, courtesy of (click to enlarge).