SCIENCE TODAY: Asteroid discovered in Earth’s orbit

The Earth has its own well-behaved celestial Chihuahua on a leash.

Two Canadians astronomers are among a team that has discovered our planet’s first Trojan asteroid, which is rotating the sun in our orbit.

“The interesting thing is that it is synchronized with the Earth,” Professor Paul Wiegert of the University of Western Ontario told the Star on Thursday.

“The asteroid always remains a little ahead, like a dog on a leash.”

At 300 metres wide, it is a small dog to our nearly 12,800 kilometres. The discovery, made last year by NASA’s WISE satellite and confirmed in April after months of peering through the Canada France Hawaii Telescope in Hawaii, has immediate implications for our understanding of Earth’s neighbourhood and long-term possibilities for space exploration.

“This asteroid is among the safest,” said Wiegert. “It never gets particularly close to the Earth, but it doesn’t wander too far away. There is a distinct gravitational link”

Wiegert’s horseshoe simulation of the orbit of “2010 TK7” shows “how far the dog is allowed to visit on its leash.”

Now about 80 million kilometres from Earth, it won’t come any closer than 24 million kilometres in the next 100 years, at least.

Most asteroids are clustered in a belt near Mars. While Trojan asteroids, named because of the complicated “tango” they perform with planets, were proposed in 1772 and discovered near Jupiter in 1906, this one is the first for Earth.

The simple brightness of the sun and the daytime sky prevented astronomers from discovering it, said Wiegert. The infra-red technology of the WISE satellite launched in 2009 spotted it and a team led by Martin Connors of Athabasca University in Alberta were finally able to track it.

“If you find one of something, you can convince people to help you find others,” said Connors, who has been searching for the Trojan asteroid for 20 years.

This discovery, published Thursday in the journal Nature, or a later discovery could eventually provide a handy landing spot for a space probe, extending our eyes and ears further into the universe, said Connors.

“NASA does want to do deep-space missions,” he said. “You can land on an asteroid very easily. They’re easier to get to than the moon, even if they are further away.”

A probe could also tell scientists which rare earth metals are inside the barren rock that we now know is with us as we orbit the sun.