A nearly 98 percent chance it won’t hit us is pretty good. Second, while that’s definitely a massive rock, it’s not like a dinosaurs-killing size. Three hundred feet wide is about on par with the asteroid that exploded over Siberia in 1908 (also known as the 1908 Tunguska Event).

Scientists say the threat of a newly discovered asteroid has risen slightly in the past few weeks, as the world's telescopes rush to track its course.