Comet Holmes (17P) Becomes a Naked Eye Comet.
http://www.skyandtelescope.com/observing/home/10775326.html
Unexpected brightening by one million times or so last happened 115 years ago.
Northern Hemisphere and well placed for viewing too.
Too cloudy to see here because the fog came in but you probably won't see another as bright for years if you miss this one.