Asteroid stalks Earth in weird horseshoe-shaped orbit
A newfound asteroid has been discovered to be trailing Earth on an oddball course: an orbit that looks a lot like a horseshoe. The space rock, called Asteroid 2010 SO16, has been following Earth as our planet orbits the sun for at least 250,000 years and is up to 1,312 feet (400 meters) wide. It was initially spotted by NASA’s WISE infrared space observatory.
Asteroid 2010 SO16 takes about 175 years to travel from one end of its orbit to another before doubling back. In diagrams, the asteroid’s orbit resembles a giant letter “C” with the Earth ticked between the endpoints. Currently, the asteroid is at a point in its orbit that brings it near the horseshoe’s tip that trails the Earth. But despite its apparent attachment to Earth’s orbit, the asteroid poses no risk of smacking our planet.
The space rock could have been ejected from the solar system’s main asteroid belt between the orbits of Mars and Jupiter, or may be a wayward member of a group of asteroids that may lurk at stable gravitational spots ahead of and behind the Earth. It could also be a chunk of Earth’s moon kicked up during an ancient impact, a leftover remnant from the formation of the solar system 4.5 billion years ago.
Image: An image of the asteroid 2010 SO16 taken by astronomers using the Faulkes Telescope North.
Ref: arxiv.org/abs/1104.0036: “A Long-Lived Horseshoe Companion To The Earth”
Another of Earth’s many moons.