Newly discovered asteroid follows the Earth as it orbits the Sun, and has been doing it for a quarter million years.
Currently, three other horseshoe companions of the Earth are known to exist but, unlike 2010 SO16, these linger for a few thousand years at most before moving on to different orbits. Also, with an estimated diameter of 200–400 metres, 2010 SO16 is by far the largest of Earth’s horseshoe asteroids. The team has already used the Las Cumbres Observatory’s Faulkes Telescope in an on-going campaign to track the object and refine its orbit further. “It is not that difficult to spot with a medium-sized professional telescope”, says Dr Asher. “It will remain as an evening object in Earth’s skies for many years to come.”