What would happen if a comet hit Earth?

A comet strike on Earth would depend on three things: size, speed, and where it lands. Long-period comets hit at about 51 kilometers per second on average, roughly three times faster than a typical near-Earth asteroid, so a comet can carry about twice the energy of a rocky asteroid of the same size. Smaller impacts, like Tunguska in 1908 and Chelyabinsk in 2013, caused airbursts, while a 10-kilometer impact like Chicxulub, 66 million years ago, reshaped life on Earth. NASA’s planetary defense work, including the DART mission, focuses on finding and deflecting threats early, but comets may give only months of warning. Video Credit: NASA; Getty Images Image Credit: NASA; NASA/JPL-Caltech; NASA/JPL-Caltech/UMD; NASA/JPL-Caltech/University of Arizona; NASA/MSFC/Aaron Kingery; Getty Images; ©ESA/ScienceOffice.org; A.I. Generated Visuals