In mapping the original locations of Saturn and Jupiter in our Solar System, astronomers have found that there was once another planet that existed between them.
"We now know that there are thousands of planetary systems in our Milky Way galaxy alone. But it turns out that the arrangement of planets in our own Solar System is highly unusual, so we are using models to reverse engineer and replicate its formative processes," says Matt Clement, lead author of the research.
"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."
Previously, astronomers had thought that in its early days, Jupiter completed three full orbits around the sun for every two undertaken by Saturn. The present research, however, found that this may not be the case.
From around 6,000 simulations of our Solar System's evolution, the researchers found that Jupiter's starting arrangement, as previously stated, was unable to account for the planet's position today. As such, they instead found that Jupiter more likely completed two trips around the sun for each made by Saturn.
They also found that the orbits of 'ice giants' Uranus and Neptune were likely influenced by the gravitational pull of the Kuiper belt- a ring of icy dwarf planets and planetoids, in which Pluto is the largest. Also affecting their orbit, however, was what is likely to have been another planet- an ice giant lurking between Saturn and Uranus that has since been expelled from our Solar System.
All in all, the researchers say that their findings show that our Solar System may have had more normal developmental origins than once thought. They also say that they can now use the present model of our Solar System's evolution to look for similar systems elsewhere with the potential to host life.