By Ron Cowen
In less than 24 hours, a small, faint comet became 400,000 times brighter late last month, blossoming into a fuzzy, starlike apparition visible to the naked eye. Now, 3 weeks after its spectacular flare-up, Comet 17P/Holmes remains visible to the naked eye in the constellation Perseus, which stands nearly overhead from the United States soon after midnight.
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![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2007/11/7267.jpg?resize=300%2C268&ssl=1)
Many comets brighten as they near the sun. Heat vaporizes volatile ices on a comet’s surface, throwing out fine, highly reflective dust particles in the process. But Holmes, which has a 6.88-year orbit, never gets any closer to the sun than twice Earth’s distance. Even more puzzling, the brightening took place about 5 months after the comet’s closest approach.