According to astronomers at NASA’s Center for Near-Earth Object (NEO) Studies, a near-Earth asteroid designated 2016 HO3 is currently following a stable quasi-satellite orbit with respect to our planet. This episode started almost a century ago and it will end hundreds of years from now.
Asteroid 2016 HO3 has an orbit around the Sun that keeps it as a constant companion of our planet. This is an artist’s impression of an asteroid. Image credit: Mark A. Garlick, Space-art.co.uk / University of Warwick / University of Cambridge.
Earth has one permanently bound satellite, the Moon, a large number of mini-moons, and several temporary quasi-satellite companions.
These quasi-satellites are 2004 GU9, 2006 FV35, 2013 LX28 and 2014 OL339.
They are not real, gravitationally bound satellites but, from Earth’s point of view, they appear to travel in the retrograde direction around it over the course of a year although they actually orbit the Sun.
“One other asteroid — 2003 YN107 — followed a similar orbital pattern for a while over ten years ago, but it has since departed our vicinity,” said Dr. Paul Chodas, manager of NASA’s Center for NEO Studies.
The newfound quasi-satellite, 2016 HO3, is likely larger than 120 feet (40 m) and smaller than 300 feet (100 m).
It was first spotted on April 27 by the Pan-STARRS (Panoramic Survey Telescope & Rapid Response System) PS 1 telescope on Haleakala, Hawaii.
According to Dr. Chodas, 2016 HO3 is the most stable example to date of an Earth’s quasi-satellite.
“2016 HO3’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,” he said.
“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.”
