Earth has a little asteroid pal that has danced with it around the solar system for 100 years

The diminutive space rock will play "leap frog" with Earth for hundreds of years, sometimes speeding ahead of our planet and occasionally falling behind, NASA said.

"The asteroid's loops around Earth drift a little ahead or behind from year to year, but when they drift too far forward or backward, Earth's gravity is just strong enough to reverse the drift and hold onto the asteroid so that it never wanders farther away than about 100 times the distance of the moon," Paul Chodas, manager of NASA's Center for Near-Earth Object (NEO) Studies, said in a statement.

"The same effect also prevents the asteroid from approaching much closer than about 38 times the distance of the moon. In effect, this small asteroid is caught in a little dance with Earth."

The asteroid, named 2016 HO3, was discovered in April 2016 by an asteroid-hunting telescope in Hawaii, and scientists think it's anywhere from 120 feet to 300 feet in length. 

The asteroid's orbit has been mapped far into the future, and it poses no threat to Earth.

2016 HO3 is a little too far from Earth for scientists to consider it a proper natural satellite (like the moon), according to NASA, instead opting to call it a "quasi-satellite." 

"One other asteroid — 2003 YN107 — followed a similar orbital pattern for a while over 10 years ago, but it has since departed our vicinity," Chodas said.

2016 HO3 isn't going anywhere anytime soon, however.

NASA scientists have found that the asteroid has been Earth's cosmic buddy for about 100 years, and it will continue to accompany the planet in orbit around the sun for centuries more, never coming closer than about 9 million miles from our world. 

The Earth occasionally traps little space rocks in its orbit that will circle the planet for some time. These "mini-moons" typically orbit our planet for about a year or a less, and there is usually at least one captured asteroid circling Earth at any given time, NASA has said.