Comet 17/P Holmes

A small and very faint comet has surprised observers around the world by overnight becoming bright enough to see with the unaided eye.

Comet Holmes, which was discovered in November 1892 by Edwin Holmes, in London England, was no brighter than magnitude 17 in mid-October - that's about 25,000 times fainter than the faintest star that can normally be seen without any optical aid. In order to view an object this faint, one would need a moderately large telescope.

But the comet's brightness has suddenly rocketed all the way up to 3rd-magnitude, brightening nearly 400,000-times in less than 24-hours! On this astronomers scale, smaller numbers mean brighter objects. From urban locations, a 3rd-magnitude object might be hidden by light pollution, but under rural skies it would be clearly visible.