It looks like our solar system is getting into the Halloween spirit and throwing us quite a curveball: A large asteroid is going to come veryyyy close to earth on October 31.The asteroid (a.k.a. 2015 TB145 ) circulates by us every three years, so you’d think we’d have known about it before now. But astronomers weren't able to see it until earlier this month, thanks to its weird orbit; this 1,200-foot-wide hunk of rock is entering our solar system at a bizarre angle."The planets all revolve around the sun in a plane, and asteroids also generally stick close to that plane," says Paul Chodas, PhD, manager of the Center for Near Earth Object Studies at NASA's Jet Propulsion Laboratory . "This orbit is quite a bit different — it’s tilted way down, so the asteroid is coming towards the earth from below."So for scientists to notice the asteroid, earth (and our friend 2015 TB145) had to be in precisely the right spot — which hasn't happened since 1975, says Dr. Chodas. And the fact that the thing is moving really quickly doesn't help.Although the asteroid will be close to us on an astronomical scale, it will still be about 300,000 miles away — a little further than the moon. So (bummer alert) you won't be able to see it with your eyes alone. But any amateur astronomers in the Northern hemisphere who know where to look (with the help of a handy star chart and a small telescope) will have a great view, Dr. Chodas says.Asteroids of this size don't come by very often. Dr. Chodas says we get one this large and this close roughly every five years. But the next one (that we know about) won't be around until 2027. So once you're stuffed with candy, make friends with your local astronomers this weekend and welcome this weirdo asteroid to your Halloween party.