Earth's immense solitude as it traverses the orbital path around the Sun can now be a thing of the past! Earth has got the company of a little asteroid which it can chase around for a little fun in the rarified sphere of gravitational forces. One of a breed of suspected celestial companions that course along Earth's orbit around the Sun has been discovered by astronomers, proving a long-held theory that space rocks dancing ahead of our planet are in existence.

With the finding of an Asteroid temporarily named as 2010 TK7, astronomers have got the proof they have been waiting for to establish that Earth has joined Jupiter, Neptune and Mars which were proved to have asteroid companions in their orbits. These asteroids are called Trojans.

Given that visitations of asteroids are always viewed with an element of fear and anxiety down here, how unsettling is the revelation that multiple asteroids of various sizes could be sharing our planet's orbital path?

The regular questions are, will these asteroids stay on the orbit, or drift away and near, or will they crash into our planet? The answer depends on exactly where in Earth's orbital path the asteroid is paced, according to the University of Western Ontario (UWO). There are five points on or near the Earth's orbit, known as the Lagrange points, where an asteroid will remain stationary with respect to the Earth.

Asteroids placed exactly on the 'L-points' tend to stay there indefinitely, provided there are no perturbations caused by other planets in the Solar System. But the truth is that such perturbations are there, which affect the course of asteroids placed at the L1, L2 and L3 points.

However, those placed in the 'L4 and L5 points' are stable and unlikely to wander away in time, says UWO.

"All the planets in our Solar System have Lagrange points, just as Earth does. As of July 27 2011, thousands of asteroids have been discovered near Jupiter's L4 and L5 points, and four at Mars' and seven at Neptune's. Only one currently known for the Earth, 2010 TK7," according to UWO.

The Asteroid 2010 TK7 was discovered by NASA's Wide-field Infrared Survey Explorer (WISE), which was launched in 2009.
The Trojan, which follows a chaotic orbital path, is 300 meters across in size and is ahead of Earth in its orbit by about 50 million miles. Astronomers estimate that the asteroid may not pose danger to Earth as it sits on a gravitational "sweet spot". Asteroid 2010 TK7 is not expected to come closer than about 25 million km from Earth and its orbit looks stable for about next 10,000 years.

So the space rock is one of those hypothesized companion which dance alongside Earth in its orbital path. The Trojan asteroid’s location in the sky, as observed from Earth's surface, is fixed at about 60 degrees east and west of the Sun.

"It's as though the Earth is playing follow the leader," said Amy Mainzer, the principal investigator of NEOWISE at NASA's Jet Propulsion Laboratory, describing how Earth and the Trojan asteroid move along in the orbit. "Earth is always chasing this asteroid around."

According to scientists, these asteroids could be possible future destinations for space missions. They could contain elements that rare on Earth's surface as well. However, astronomers say 2010 TK7 may not be an ideal target for a mission as it 'travels above and below the plane of Earth's orbit,' according to space.com.

However, the discovery has confirmed the existence of Earth Trojans, and some of these could qualify for a mission in future. "We could be mining these things one day," said study co-author Martin Connors, an astronomer at Athabasca University in Canada.

Asteroid Earth Jupiter Mars