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Earth’s Constant ‘Second Moon’ Spotted

A small asteroid, designated 2016 HO3, has been discovered in our solar system that keeps constant companionship with Earth like the moon and astronomers say that it will remain so for centuries to come. It is 38 times farther than the moon.

As it orbits the sun like Earth, it also appears to circle around Earth as well but too far in distance to be considered a true satellite of our planet, but it is the best and most stable near-Earth companion, or “quasi-satellite.”

“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 of 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… 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,” he said.
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 the second half of the time farther away, behind Earth.

Since its orbit is slightly tilted, it bobs up and down once each year through Earth’s orbital plane, said researchers. The new asteroid is effectively caught in a game of leap frog with Earth that will last for hundreds of years, predicted JPL scientists.

The asteroid’s orbit around Earth drifts 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.”

Asteroid 2016 HO3 was first spotted on April 27, 2016, by the Pan-STARRS 1 asteroid survey telescope on Haleakala, Hawaii. The size of 2016 HO3 asteroid has not yet been confirmed but it is likely to be larger than 120 feet and smaller than 300 feet.

Asteroid 2016 HO3 has an orbit around the sun that keeps it as a constant companion of Earth

Asteroid 2016 HO3 has an orbit around the sun that keeps it as a constant companion of Earth. Credit: NASA/JPL-Caltech

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