NASA astronomers using the Wide-field infrared Survey Explorer (WISE) have discovered a Trojan asteroid that has been sharing Earth's orbit around the sun.
The asteroid is roughly 1,000 feet or 300 meters in diameter and is the first known Earth Trojan asteroid, named 2010 TK7.
NASA explains that Trojans are asteroids that "orbit with a planet near stable points in front of or behind the planet." And as far as the probability of it hitting Earth, NASA explains that there isn't any due to the fact that these asteroids either lead or follow at a constant pace suggesting that it will never catch up or fall behind Earth.
"It's as though Earth is playing follow the leader," said Amy Mainzer, one principal investigator at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Earth always is chasing this asteroid around."
Trojan asteroids are not uncommon. Within the solar system, Trojans are also known to be sharing orbits with Neptune, Mars, and Jupiter in addition to two of Saturn's moons.
Martin Connors of Athabasca University in Canada and lead author of the paper on the discovery said, "These asteroids dwell mostly in the daylight, making them very hard to see, but we finally found one, because the object has an unusual orbit that takes it farther away from the sun than what is typical for Trojans. WISE was a game-changer, giving us a point of view difficult to have at Earth's surface."
According to the space agency, the WISE telescope scanned the complete sky using infrared light from January 2010 to February 2011 and found some 132 bodies that were previously unknown from which two were Trojan candidates resulting in the confirmation of one being an Earth Trojan.
JPL manages and operates WISE for NASA's Science Mission Directorate in Washington.