After much speculation, research and confirmation, it is official: NASA scientists have announced that the Earth has a second moon, known as Asteroid 2016 H03, that has been orbiting the planet for around a century.
The wee asteroid is just a few hundred feet across and was detected earlier this year from a survey telescope in Hawaii. It follows an orbital pattern taking it on slow long loops. No one is quite sure how long the body will stay in our vicinity, but gravitational forces seem intent on keeping it around, at least for a while.
Paul Chodas, manager of NASA’s Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory, explains that because of its distance, this object is “quasi-satellite” of Earth. “Its loops 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. 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.”