Keeping an Eye on Space Rocks
JPL manages NASA’s Center for Near-Earth Object Studies, which tracks comets and asteroids that drift close to Earth’s orbital neighborhood.
A Near-Earth Object (NEO) is generally defined as an asteroid or comet that approaches our planet less than 1.3 times the distance from Earth to the Sun (the Earth-Sun distance is about 93 million miles). Most NEOs pose no peril at all. It’s the small percentage of Potentially Hazardous Asteroids that draws extra scrutiny. These objects are defined as those that approach Earth at less than half the Earth-Sun distance.