NASA's IMAP mission and two other spacecraft launched atop a SpaceX Falcon 9 rocket early Wednesday morning (Sept. 24) to study space weather and its effects on Earth.
Asteroids are rocky remnants from the early Solar System, chunks of stone and metal that range in size from pebbles to mountains. Most of them orbit peacefully in the asteroid belt between Mars and Jupiter, but occasionally gravitational forces can nudge them toward Earth. The largest asteroid, Ceres, is almost 1,000 km across, while the one that likely killed the dinosaurs was roughly 10 km wide. Even relatively small asteroids can cause tremendous damage for example, the space rock that created Arizona's famous Meteor Crater was only about 45 metres across, yet it generated a crater just over 1km wide.

