'Trojan' Asteroid Detected Sharing an Orbit with Uranus

For the first time ever, astronomers have discovered a Trojan asteroid sharing an orbit with Uranus.

Trojan asteroids are those which share an orbit of a planet, occupying two stable positions known as Lagrangian points. For this reason, researchers have long deemed their presence in Uranus's orbit unlikely, assuming that the gravitational pull of larger neighboring planets would destabilize it and ultimately send it off in another direction.

However, astronomers from the University of British Columbia have identified a 60-kilometer-wide ball of rock and ice that, they say, may be indicative of a larger-than-expected population of transients objects trapped temporarily by the pull of the solar system's giants.

In order to determine how it ended up there, the astronomers created a simulation of the solar system and its co-orbital objects, including Trojans.

"Surprisingly, our model predicts that at any given time three [percent] of scattered objects between Jupiter and Neptune should be co-orbitals of Uranus or Neptune," Mike Alexandersen, lead author of the study published in the journal Science, said in statement.

This number represents the first time the percentage has ever been computed and is much higher than previous estimates.

Over the last decade, researchers have identified several temporary Trojans, of which the latest is just one. According to the scientists, it was likely only ensnared by Uranus within the last couple hundred thousand years and is set to escape within another million or so.

"This tells us something about the current evolution of the Solar System," Alexandersen said. "By studying the process by which Trojans become temporarily captured, one can better understand how objects migrate into the planetary region of the Solar System."

Other researchers included Brett Gladman and Sarah Greenstreet, also of of UBC, and scientists at the National Research Council of Canada and the Observatoire de Besancon in France.