Researchers from NASA have confirmed that the Moon is no longer the Earth’s only natural satellite.
It has been joined by what is referred to as a ‘mini-moon’ which has been named asteroid 2016 HO3 by the team that discovered it. It is believed that it has been orbiting the planet for at least one hundred years.
A second moon is orbiting the Earth
While the orbit of the original Moon is spherical, stable and easily predictable, the new mini-moon is showing more irregular tendencies. The mini-moon is much smaller than both the Earth and the Moon and is being tugged around by their competing gravitational forces. This means that it is moving back and forth towards the Earth. Paul Chodas, manager of NASA’s Center for Near-Earth Object (NEO) Studies at the Jet Propulsion Laboratory in Pasadena, California, explains, “The asteroid’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.” The Moon has the same effect on the mini-moon and exerts its own gravitational force which prevents the smaller moon from getting to close to it. “In effect, this small asteroid is caught in a little dance with Earth, ” Chodas concluded.
NASA have been swift to reassure the public that there is no danger posed by the mini-moon either to Earth or to the planet’s primary natural satellite. The scientists believe that it has been peacefully caught between the gravitational forces of the two bodies for at least a century and that it will remain caught in orbit for many hundreds of years to come.
But if the mini-moon has been in orbit for a hundred years, why has it taken astronomers so long to detect it? The reason for this is the extraordinarily small size of the mini-moon. Researchers estimate that it only measures 120 feet across and is no more than 300 feet wide.