Scientists at Southwest Research Institute studied an unusual pair of asteroids and discovered that their existence points to an early planetary rearrangement in our solar system.
These bodies, called Patroclus and Menoetius, are targets of NASA’s upcoming Lucy mission. They are around 70 miles wide and orbit around each other as they collectively circle the Sun. They are the only large binary known in the population of ancient bodies referred to as the Trojan asteroids. The two swarms of Trojans orbit at roughly the same distance from the Sun as Jupiter, one swarm orbiting ahead of, and the other trailing, the gas giant.
“The Trojans were likely captured during a dramatic period of dynamic instability when a skirmish between the solar system’s giant planets — Jupiter, Saturn, Uranus and Neptune — occurred,” said SwRI Institute Scientist Dr. David Nesvorny. He is the lead author of the paper, “Evidence for Very Early Migration of the Solar System Planets from the Patroclus-Menoetius Binary Jupiter Trojan,” published in Nature Astronomy. This shake-up pushed Uranus and Neptune outwards, where they encountered a large primordial population of small bodies thought to be the source of today’s Kuiper Belt objects, which orbit at the edge of the solar system. “Many small bodies of this primordial Kuiper Belt were scattered inwards, and a few of those became trapped as Trojan asteroids.”