Asteroid 1999 KW4 made its closest approach to Earth this weekend and was still visible today.
It is so large (approximately 1.3 kilometers in diameter) that is has its own moon orbiting around it.
It was traveling at about 77,000 km/h.
Asteroid 1999 KW4, was discovered 20 years ago.
It is classified as a near-Earth object and potentially hazardous asteroid.