Twin Asteroids Hint At Violent Clash Between The Planetary Giants

Today, the solar system exists in relative peace. History, however, tells another story as a newly discovered pair of asteroids hint at a tumultuous past.

The mere existence of the ancient Trojan asteroids named Patroclus and Menoetius reveals a lot about the solar system, particularly a planetary rearrangement that occurred in its early years.

A Brawl Among Planets

The study, published in the journal Nature Astronomy, reveals that Patroclus and Menoetius are the only large binary system in the ancient group known as the Trojan asteroids. The twin asteroids orbit around each other in their collective orbit around the sun at about the same distance from the star as Jupiter.

"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," Dr. David Nesvorny, lead author and scientist at the Southwest Research Institute, explains in a statement.

It is this violent brawl that pushed Uranus and Neptune to the outskirts. Here, the two planets came across small cosmic objects that are believed to be the origins of today's Kuiper Belt. During this encounter, some of these small bodies made its way inward and became trapped inside the solar system as part of the Trojan asteroids.

Binary Systems In Prehistoric Times

Binary asteroids Patroclus and Menoetius appear to be part of this group of small bodies swept into the solar system, getting caught in the Trojans in the process.

After all, binary systems were much more common in the earliest years of the solar system. Back then, the authors explain, small bodies could pair up as clouds of pebbles collapsed.

"Observations of today's Kuiper Belt show that binaries like these were quite common in ancient times," William Bottke, co-author of the study and director of SwRI's space studies department, adds. "Only a few of them now exist within the orbit of Neptune. The question is how to interpret the survivors."

As the solar system developed and became more populated with small objects, such binaries are much more likely to be disrupted, according to UPI.

Evolution models indicate that if the solar system's planetary instability occurred hundreds of millions of years later, there would have been no binaries left to capture, as most would have been destroyed by collisions. This suggests that the Patroclus and Menoetius binary was likely captured early on, essentially ensuring the system's survival.