It's expected that a nearly a mile wide asteroid with its own moon will pass on Earth this weekend and travel at a speed of 48,000 miles per hour. The space rock known as Asteroid 1999 KW4 was discovered 20 years ago and is so large that it is orbited by a moon.
On Saturday night 1999, KW4 approaches Earth the next. It will be visible until May 27th. Since it contains a big moon, the asteroid is technically called a binary system.
NASA defines a binary system as two celestial objects that are close enough together to form an orbit.
The Las Cumbres Observatory describes KW4 as "slightly bruised at the poles and with a ridge around the equator running around the asteroid in 1
The asteroid was first discovered, according to NASA, by the Near Earth Asteroid Research Survey (LINEAR) of the Lincoln Laboratory in Socorro, New Mexico. The asteroid will not be that close to Earth until 2036.
The Smithsonian Astrophysical Observatory's Minor Planet Center classified KW4 as a "potentially dangerous asteroid" in 1999 as it will travel relatively close to Earth. Even so, the asteroid will only be about 5.2 million miles from Earth – about 13 times the distance between Earth and the Moon.