Asteroids share orbits with planets, without crashing. A first for Uranus.
Sean Ardley stashed this in Asstronomy
"Scientists thought the Trojan points of Uranus, the seventh planet from the sun, were too unstable to host asteroids. Now astronomers using the Canada-France-Hawaii Telescope have discovered the first Trojan for Uranus."
Pretty astonishing discovery, actually.
Based on this new data, the researchers calculate that about 0.1 percent of all the asteroids and comets 6 to 34 astronomical units from the sun are Uranian Trojans at any given time, meaning Uranus has a virtually constant population of companions. They also estimated about 1 percent of all the asteroids and comets beyond Jupiter's orbit are Neptunian Trojans.
"This might trigger a wave of searches for Uranian Trojans — now that people know they exist, it will be easier to get telescope time to search for them than when it was thought unlikely to find anything," Alexandersen said.
These temporary Trojans reveal objects traveling inward from the outer fringes of the solar system"aren't just being scattered all over the place in a seemingly chaotic fashion," Alexandersen said. "There are in fact these small reservoirs where objects get temporarily stuck, just like how sticks flowing down a river can sometimes get temporarily stuck circling in eddies or calm pools before finally escaping to continue down the river."