Comet 45P/Honda-Mrkos-Pajduáková is what its called. Those names are the astronomers who first noticed it out there in space back in 1948. It takes over 5 years for it to make a full orbit and become visible here on earth, and it was first visible this year back on the 15th, but it was on the horizon and hard to see. Tomorrow night before all of our New Year celebrations (around 6:30-ish), youll be able to see it more easily. It will be basically right next to the moon and look like a faint star but if youve got good eyesight, youll know what it is.
Youll probably need binoculars to see it, or a telescope if you have one, but theyre pretty cool to look at nonetheless. Check out more information HERE