In 5 and a half years from now in 2029, an asteroid as big as the Empire State Building will come within 20,000 miles of Earth, the closest any asteroid will come to Earth ever. A NASA satellite launched in 2016 will provide a very close look at this rare encounter. 

By getting a close look at this asteroid it could give insight on how to build a defense system for any possible doomsday asteroid collisions with Earth. This asteroid was discovered in 2004 and was named Apophis after an evil demon serpent in ancient Egyptian mythology. When first discovered scientists thought it was on a course to collide with Earth, but now with further research a collision is ruled out. 

The satellite that will observe this asteroid is called the OSIRIS-APEX and this is not the satellite’s first mission. Three years ago it plucked a dirt sample from a different asteroid, then was sent back to Earth in a capsule. 

Apophis is believed to be made of mostly silicate, iron, and nickel materials. Since this asteroid will be coming so close to Earth it will be visible to the naked eye for a couple of hours. An asteroid this size and passing close to Earth is estimated to happen once every 7,500 years, so this is a predicted encounter. 

Once this asteroid passes by it will also inform us how asteroids passing by Earth change asteroids orbital path and spin. The OSIRIS-APEX is planned to stay next to the Apophis for 18 months, orbiting, moving, and even hovering right over the Apophis, gathering more and more information about it.