When the sun was young, it was surrounded by a rotating disk of gas and dust from which the planets were born. The orbits of early formed planets were believed to be initially close-packed and circular. Still, gravitational interactions between the more massive objects perturbed the arrangement and made the baby giant planets reshuffle rapidly, creating the configuration we see today.
Carnegie’s Matt Clement said, “There are thousands of planetary systems in our Milky Way galaxy alone. But it turns out that the arrangement of planets in our Solar System is highly unusual, so we use models to reverse engineer and replicate its formative processes. This is a bit like trying to figure out what happened in a car crash after the fact — how fast were the cars going, in what directions, and so on.”
A new study- by the Carnegie Institution for Science- now revealed the likely original locations of Saturn and Jupiter. Likewise, the course refines our understanding of the forces that determined our Solar System’s unusual architecture, including the ejection of an additional planet between Saturn and Uranus, ensuring that only small, rocky planets, like Earth, formed inward of Jupiter.
For the study, scientists conducted 6,000 simulations of our Solar System‘s evolution. It reveals an incredible detail about Jupiter and Saturn’s original relationship.
In its earlier days, Jupiter was thought to be orbiting the Sun three times for every two orbits that Saturn completed. However, this arrangement doesn’t satisfactory explain the configuration of the giant planets that we see today.
The new model developed by scientists has shown that the ratio of two Jupiter orbits to one Saturnian orbit more consistently produced results that look like our familiar planetary architecture.
Clement said, “This indicates that while our Solar System is a bit of an oddball, it wasn’t always the case. What’s more, now that we’ve established the effectiveness of this model, we can use it to help us look at the formation of the terrestrial planets, including our own, and to inform perhaps our ability to look for similar systems elsewhere that could have the potential to host life.”
The model also showed that the positions of Uranus and Neptune were shaped by the mass of the Kuiper belt — an icy region on the Solar System’s edges composed of dwarf planets and planetoids of which Pluto is the largest member — and by an ice giant planet that was kicked out in the Solar System’s infancy.
- Matthew S. Clement, Sean N. Raymond, Nathan A. Kaib, Rogerio Deienno, John E. Chambers, André Izidoro. Born eccentric: Constraints on Jupiter and Saturn’s pre-instability orbits. Icarus, 2021; 355: 114122 DOI: 10.1016/j.icarus.2020.114122