The Comet That Suddenly Exploded in Brightness
In October 2007, a faint comet brightened about half a million times in less than two days, becoming a fuzzy ball visible without a telescope.
What was reported
Comet Holmes was discovered in 1892 by the English amateur astronomer Edwin Holmes in London, when it suddenly became bright. Then it faded and was nearly forgotten.
On 23 October 2007, it did it again. In about 42 hours, it brightened by a factor of around half a million, becoming easily visible with the naked eye as a yellowish star, then swelling into a glowing ball of dust that, for a while, was wider than the Sun itself.
Explanations offered
The outburst was caused by a sudden release of gas and dust from the comet's nucleus, perhaps from a collapse or a burst of trapped ice turning to gas. Why such a huge outburst happened, and why twice, is still not fully understood.
- When
- 1892 and October 2007
- Where
- London, England, UK
- Witnesses
- Edwin Holmes, then sky-watchers around the world
- Status
- Partly explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.
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