They include about thirteen thousand near-Earth asteroids ( NEAs ) , more than one hundred near-Earth comets ( NECs ) , and a number of solar-orbiting spacecraft and meteoroids , large enough to be tracked in space before striking the Earth .
They include more than ten thousand near-Earth asteroids ( NEAs ) , near-Earth comets , some solar-orbiting spacecraft , and meteoroids large enough to be tracked in space before striking the Earth .