Associated Press — University of California at Los Angeles planetary scientist David Jewitt, who is credited with detecting the first Kuiper Belt object in 1992, said that the transneptunian region is the source of all sorts of objects hurtling about the solar system, providing an Armada-like "rain of stuff" cascading inward toward the sun. As they move about, they get caught up in planets' gravity — either getting hurled away or thrown further inward.
Chunks that float around in the zone of the giant planets are called Centaurs. Those that make it into the inner solar system, heating and vaporizing in the sun's heat, are known as comets.
Trojans are the bits that get captured in particular locations in a planet's orbit where gravity from the sun and gravity from the planet interact to lock them in place.
Some Trojans — around Mars, Neptune and especially Jupiter — are permanently bound to their planets, and have been for billions of years. Others, like 2011 QF99 and Earth's Trojan 2010 TK7, are only temporarily trapped in their orbits.
"The planets are playing ball with this thing," Jewitt said of the newly detected object. "Eventually they'll lose control of it."
Alexandersen and his colleagues conducted a computer simulation that showed that the Trojan — which is about 37 miles wide — is only temporarily bound to Uranus. Sometime within the next million years, it's likely to drop out of its orbit and become a Centaur, they reported in Science.