NEW YORK — Like a poodle on a leash, a tiny asteroid runs ahead of Earth on the planet’s yearlong strolls around the sun, scientists report.
The discovery of this companion, which measures only about 300 yards across, makes Earth the fourth planet in the solar system that’s known to share its orbit with an asteroid.
Imagine Earth and the asteroid traveling around a clock face, with the sun in the middle. Generally, the asteroid runs about two numbers ahead.
However, the asteroid sometimes ranges so far ahead that it’s on the opposite side of the sun from Earth, said Martin Connors of Canada’s Athabasca University in Alberta. He reports the work with colleagues in today’s issue of the journal Nature.
Asteroids are giant space rocks that orbit the sun, and ones that share an orbit with a planet are called Trojans. Scientists had previously found a few for Mars and Neptune and nearly 5,000 for Jupiter.
Trojan 2010 TK7 was discovered last year by NASA’s WISE satellite. The Widefield Infrared Survey Explorer was built by Ball Aerospace & Technologies Inc. of Boulder and launched in December 2009 by United Launch Alliance of Centennial.
The Associated Press
