Earth has only one true natural satellite: the moon. But now scientists have found a fellow satellite of the sun that's been our constant companion for more than 100 years. Because of the way the space rock wobbles in orbit, it actually circles our own planet in addition to circling the sun.
Meet 2016 HO3, the little asteroid buddy we never knew we had. Our celestial pal was discovered in April using the Pan-STARRS 1 asteroid survey telescope on Haleakala, Hawaii.
Because 2016 HO3's orbital plane wobbles like a hula hoop slowly settling onto the ground, it leapfrogs up and over Earth as both bodies make their way around the sun. Take a look. It's pretty funky:
"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," Paul Chodas, manager of NASA's Center for Near-Earth Object Studies at the Jet Propulsion Laboratory, said in a statement.
2016 HO3 is never more than 100 times farther away than the moon, but it's also never closer than 38 times that distance. For now, there's no firm measurement of the object. But scientists suspect that it has a diameter somewhere between 120 and 300 feet. D'aw.
"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. "This new asteroid is much more locked onto us. Our calculations indicate 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."