Our solar system might have been a vastly different place before Jupiter arrived, according to a new Proceedings of the National Academy of Sciences that suggests that the gas giant may have destroyed an entire generation of inner planets before entering its current orbit.
In the study, researchers from the University of California, Santa Cruz propose that Jupiter may have “swept through the early solar system like a wrecking ball,” destroying an entire generation of inner planets and causing many of our solar system’s quirks before finally settling in.
As co-author and UCSC astronomy professor Gregory Laughlin explained, “Now that we can look at our own solar system in the context of all these other planetary systems, one of the most interesting features is the absence of planets inside the orbit of Mercury. The standard issue planetary system in our galaxy seems to be a set of super-Earths with alarmingly short orbital periods. Our solar system is looking increasingly like an oddball.”
A grand attack
Laughlin and co-author Konstantin Batygin explore what Discovery News refers to as the Grand Tack theory of our solar system’s formation. This theory suggests that during its infancy, Jupiter was swept up in the gravitational wake of its own buildup and spiraled inward, colliding with the would-be planets and asteroids unlucky enough to get in its way.
The result would not be unlike a break shot in a game of pool, scattering these objects all over the place and causing a chain reaction that could have easily destroyed any planet in the area, the study authors explained. It wasn’t until Saturn formed and evolved that the rampage stopped, due to the newer gas giant’s counteracting Jupiter’s inward spiral, allowing it to settle into position beyond Mars and clearing the way for a second-generation of planets (including Earth) to form.
The planets destroyed as a result of Jupiter’s activity and the resulting debris would have been recently-formed super-Earths that were likely driven into the sun, the UCSC researchers added. In contrast, the second-generation worlds that formed from material that had been left behind, would have less mass and thinner atmospheres than would have otherwise been anticipated.
“This kind of theory, where first this happened and then that happened, is almost always wrong, so I was initially skeptical,” Laughlin said. “But it actually involves generic processes that have been extensively studied by other researchers. There is a lot of evidence that supports the idea of Jupiter’s inward and then outward migration. Our work looks at the consequences of that. Jupiter’s ‘Grand Tack’ may well have been a ‘Grand Attack’ on the original inner solar system.”
Pretty. Violent. (Girl punk rock duo?)
The computer models used by Laughlin and Batygin indicated that conditions during the early solar system would have been ideal for multiple, high-speed collisions, Discovery News noted. Those collisions would have been “pretty violent,” Laughlin explained, taking place at speeds of five kilometers per second and involving 100-kilometer objects. The events would have been “energetic and damaging,” with one set of collisions causing a domino effect that led to others.
“If our solar system had started out as a normal, standard-issue solar system, it shows that the Grand Tack could have very handily kind of wiped the slate clean and destroyed any planets that originally were interior to Mercury’s orbit,” the UCSC professor told the website.
We imagine the whole thing looked like this: