Washington: Our Earth has got a small companion. NASA scientists have discovered a tiny asteroid in an orbit around the Sun that keeps it as a constant companion of Earth and will remain so for centuries to come.
As it orbits the sun, this new asteroid named "2016 HO3" appears to circle around the Earth as well. It is too distant to be considered a true satellite of our planet but it is the best and most stable example to date of a near-Earth companion or "quasi-satellite".
The size of this object has not yet been firmly established but it is likely larger than 120 ft and smaller than 300 ft.
"Since '2016 HO3' loops around our planet but never ventures very far away as we both go around the Sun, we refer to it as a quasi-satellite of Earth," said Paul Chodas, manager of NASA's Centre for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California.
One other asteroid named "2003 YN107" followed a similar orbital pattern for a while over 10 years ago, but it has since departed the vicinity.
"This new asteroid is much more locked onto us. Our calculations indicate that '2016 HO3' has been a stable quasi-satellite of Earth for almost a century, and it will continue to follow this pattern as Earth's companion for centuries to come," Chodas added in a statement.
In its yearly trek around the sun, asteroid 2016 HO3 spends about half of the time closer to the Sun than Earth and passes ahead of our planet, and about half of the time farther away, causing it to fall behind.
Its orbit is also tilted a little, causing it to go up and then down once each year through Earth's orbital plane.
In effect, this small asteroid is caught in a game of leap frog with Earth that will last for hundreds of years.
"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," explained Chodas.
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,a he noted.
Asteroid "2016 HO3" was first spotted on April 27 by the Pan-STARRS 1 asteroid survey telescope on Haleakala, Hawaii, operated by the University of Hawaii's Institute for Astronomy and funded by NASA's Planetary Defence Coordination Office.