Far-off asteroid caught cohabiting with Uranus around the sun | New Scientist
https://www.newscientist.com/...21489-far-off-asteroid-caught-cohabiting-with-uranus-around-the-sun/
A rare Trojan asteroid of Uranus has been found, following the same orbit as the planet. Its existence implies there could be many more of these companion asteroids,
and that they are more common than we thought.
A Trojan asteroid orbits the sun 60 degrees ahead of or behind a planet. Jupiter and Neptune have numerous Trojans, many of which have been in place for billions of years.
These primordial rocks hold information about the solar system’s birth, and NASA has just announced plans to visit several of them in the 2020s and 2030s.
But Saturn and Uranus live in a rougher neighbourhood: the giant planets on either side of them yank Trojans away through their gravitational pull. So Saturn has no known
Trojan, and Uranus had only one.
In July, though, astronomers reported a new asteroid, named 2014 YX49, that shares Uranus’s orbital period of 84 years. Now computer simulations of the solar system by
brothers Carlos and Raul de la Fuente Marcos at the Complutense University of Madrid, Spain, indicate the asteroid is a Uranus Trojan. The simulations show that the asteroid
has maintained its position ahead of Uranus for thousands of years.
“It is bigger, probably twice as big as the first one,” says Carlos. The new asteroid is brighter than the first, but its exact size depends on how much light its surface
reflects. If it reflects half the sunlight striking it, it’s 40 kilometres across; if it reflects 5 per cent, its diameter is 120 kilometres.
