Zero to hero: Comet brightens 400,000 times overnight.

[Moonliner]

Comet 17P/Holmes has overnight bloomed into a 3rd magnitude naked eye comet.

Originally Posted by Bad Astronomy

Comet 17P/Holmes has brightened incredibly, from magnitude 17 to magnitude 3 literally overnight. That’s a brightening of a factor of 400,000!

It’s incredible, and it appears to be legit (see also here). The comet is in the constellation Perseus

Click here for all the details on where to see it.