On October 24, 2007, a fairly inconspicuous comet known as 17P/Holmes that was fainter than Pluto suddenly brightened to be easily visible to the naked eye and nearly as bright as Algol, the brightest star in Perseus.
The appearance of a comet varies when viewed from Earth. Use the controls to see how Comet Holmes looks through a telescope.
Comet 17P/Holmes has had a history of producing outbursts of activity; the exact cause is still unknown. Regardless of the cause, the result is that the coma of the comet expands as fresh dust is released from the comet nucleus. Snapshot 1 shows a large coma, a short tail, and an orientation that closely matches that of the comet when it underwent its most recent outburst.