Really. The Earth is the target of a 20 million ton asteroid named Apophis that's headed this way. and it'll be so close—closer than the moon— we'll be able to see it with the naked eye in both day and night-time. Recent, refined calculations indicate there's a 1-in-45,000 chance that it will hit Earth on April 13th, 2036. Another asteroid, currently with the highest known possibility of impact, has 1-in-600 chance of striking Earth in 2880.
If the asteroids land in the Pacific Ocean (likely, if for no other reason than the Pacific is so large) it could create a huge tsunami that would wreak havoc on Pacific islands and the West Coast of the US. Venezuela and Siberia are possible impact zones for Apophis too.
Previous near-earth asteroids have created a furor in the press, because such an impact could be devastating. But so far the scare has always been unfounded. Still, the day will come. NASA currently lists 127 asteroids that may hit Earth, and soon the number may be in the thousands as our search for them improves.
During the past 10 years, a concerted search effort by astronomers has led to the detection of an estimated 90% of the huge asteroids that could threaten Earth with devastation on a global scale—such as the one that killed off the dinosaurs. In the coming decade, a next-generation search is likely to uncover most of the remaining global hazards, and perhaps thousands of smaller asteroids that could cause damage on a regional scale—such as the 800-foot-wide Apophis, that could "merely" threaten millions of lives.