Looking at our solar system, the divide seems obvious: On one side there are terrestrial planets like Earth and Mars. Then, on the other side, there are the gas giants like Jupiter and Saturn.
A divide seemingly kept the material responsible for these types of planets from mixing together in the early days of the solar system, preventing outer material from mingling with the inner. But what preserved this composition?
“The most likely explanation for that compositional difference is that it emerged from an intrinsic structure of this disk of gas and dust,” said Stephen Mojzsis, study co-author and geological sciences professor at the University of Colorado at Boulder. “The Great Divide [in North America] causes water to drain one way or another. It’s similar to how this pressure bump would have divided material in the solar system.”
But the divide itself probably wasn’t a solid gatekeeper for materials, which means that there was likely some mixing. And that small mixing could be why life exists on Earth.
“Those materials that might go to the Earth would be those volatile, carbon-rich materials,” Mojzsis said. “And that gives you water. It gives you organics.”
So what does our solar system’s divide look like today? Empty space, the researchers said. The region is near Jupiter and beyond the asteroid belt, and it’s largely a void.
But looking at planets, it’s more obvious. On one side of the divide, planets and asteroids are low in organic materials. On the other, distant side — past Jupiter and heading towards the outer solar system — they are carbon-rich.
Previously, scientists believed Jupiter itself was responsible for the divide. But even the largest planet in our solar system couldn’t block rocky material from moving towards the sun.
Ultimately, scientists realized that our sun was once likely surrounded by a disk, much in the same way as other young star systems that have been observed. The distant systems resembled a tiger’s eye, based on infrared observations by the Atacama Large Millimeter/submillimeter Array of telescopes in Chile, the researchers said.