An asteroid about 2/3rds the size of a football field is heading toward Earth, arriving here on February 15.  NASA says the flyby is "the closest ever predicted Earth approach for an object this large." While it won't hit our planet this time around, there's a small chance it could collide with Earth when it circles back in 2110. Dina Spector at Business Insider points out that if an asteroid this size did hit Earth, it'd "be similar to the Tunguska asteroid, which hit Siberia in 1908."