Huge rocks from outer space, or asteroids, are falling from the sky more than they have in the past., but there is no need to worry. A new study has shown that for the past 290 million years, large asteroids have been crashing into Earth more than twice as often as they did in the 700 million years before that. The journal Science published the study in January. But, even with the increased crash rate, asteroids still only hit Earth every million or few million years. The United States space agency NASA lists its observation of large space rocks that could crash into Earth. It shows no major threats coming soon. The biggest known risk is a 1.3 kilometer wide asteroid with a 99.988 percent chance that it will miss Earth when it passes by in 861 years. University of Toronto scientist Sara Mazrouei led the study. She told the Associated Press she is not worried about asteroids hitting Earth because they are such rare events.