NASA’s WISE mission discovers ‘horseshoe’ asteroid

The orbit of the new object is circular and it cannot come close to any other planet.

Washington: An asteroid, which has recently been discovered by NASA’s Wide-field Infrared Survey Explorer (WISE), is a bit different from most near-Earth asteroids (NEAs).

The orbit of the new object, designated 2010 SO16, is almost circular such that it cannot come close to any other planet in the solar system except Earth.

However, even though the asteroid rides around with Earth, it never gets that close.

“It keeps well away from Earth,” said Apostolos “Tolis” Christou, who, together with David Asher of the Armagh Observatory in Northern Ireland, analyzed the orbit of the body after it was discovered in infrared images taken by WISE.

“So well, in fact, that it has likely been in this orbit for several hundred thousand years, never coming closer to our planet than 50 times the distance to the Moon,” added Christou.

The asteroid is one of a few that trace out a horseshoe shape relative to Earth. As the asteroid approaches Earth, the planet’s gravity mcauses the object to shift back into a larger orbit that takes longer to go around the Sun than Earth. Alternately, as Earth catches up with the asteroid, the planet’s gravity causes it to fall into a closer orbit that takes less time to go around the Sun than Earth. The asteroid therefore never completely passes our planet. This slingshot-like effect results in a horseshoe-shaped path as seen from Earth, in which 2010 SO16 takes 175 years to get from one end of the horseshoe to the other.

Data on the orbits of asteroids and comets detected by the project, including near-Earth objects, are catalogued at the NASA-funded International Astronomical Union’s Minor Planet Center, at the Smithsonian Astrophysical Observatory in Cambridge, Mass.