Astronomers found a small asteroid circling around the Earth. Estimated to be between 40 meters (120 feet) and 100 meters (300 feet), the asteroid is now named 2016 HO3.
Scientists say 2016 HO3 is too far to be considered a true satellite of Earth, like the moon. Instead, they call 2016 HO3 as the best example of a quasi-satellite or near-Earth companion we have found so far.
The difference between quasi-satellites and true satellites is the time they take to loop around Earth. A true satellite should only loop within a few months or less than a year but it takes quasi-satellites a year to loop around Earth completely.
The Pan-STARRS 1 asteroid survey telescope in Haleakala, Hawaii saw the quasi-satellite for the first time on April 27 of this year. The asteroid has actually been Earth’s companion for almost a century and will remain so for hundreds of years to come.
Its orbit is weird, as astronomers describe. Its slightly tilted position causes it to move up and down once every year. The astronomers say this demonstrates that the asteroid is caught in a “game of leap frog” with Earth, which will not stop soon.
“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,” points out Paul Chodas, the manager of NASA’s Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California. “One other asteroid — 2003 YN107 — followed a similar orbital pattern for a while over 10 years ago, but it has since departed our vicinity.”
The asteroid 2016 HO3 is closer to the sun than our Earth during half of its annual journey around the sun. Alternately, the asteroid spends half the time farther away from the sun, falling behind our planet.
According to Chodas, when the Earth and the asteroid drifts too far from each other, our planet’s gravity is capable to reverse this and prevent the asteroid from going farther away more than 100 times the distance between the Earth and moon.
“The same effect also prevents the asteroid from approaching much closer than about 38 times the distance of the moon,” adds Chodas. “In effect, this small asteroid is caught in a little dance with Earth.”