This type of object, known as a â€œTrojan,â€ compatibly shares a planetâ€™s path around the sun, thanks to a neat trick of orbital mechanics.
Trojans are fortuitously positioned in precise locations â€” called Lagrangian points â€” where gravitationally tugging by two larger bodies balances out, creating safe harbors for smaller, third objects to fly undisturbed.
Earthâ€™s Trojan, for example, is a 1,000-foot diameter asteroid that orbits in a complicated pattern some 50 million miles away. It was discovered in 2010 with NASAâ€™s Wide-field Infrared Survey Explorer, or WISE telescope.
Trojans also have been found sharing orbits with Jupiter, Mars, Neptune and two of Saturnâ€™s moons.
Scientists didnâ€™t think Uranus, the only planet that is keeled over on its side, relative to the sun, had the gravitational stability to support Trojans. But a 17-month study survey by the Canada-France-Hawaii Telescope has proven otherwise.
The newly found object, known as 2011 QF99, wonâ€™t stay with Uranus forever. Computer models show the Trojan will escape Uranusâ€™ gravitational leash in about 700,000 years.