Comet 17P/Holmes is a periodic comet which was discovered by Edwin Holmes in 1892.
It is a short-periodic comet in an inclined and elliptical orbit between Mars and Jupiter.

In October 2007, this comet experienced a dramatic increase in brightness from magnitude 17 to about 2.8 (becoming an easy naked eye object).
This increase represents an increase in brightness of a factor of about 500.000 times.
Based on data gathered from the last perihelion passage, the comet’s nucleus was estimated at 3.4 km.

By November the comet’s coma had grown to a size larger than the apparant diameter of our Sun (in the sky)