Probing the origins of the schism that separated the solar system after the Sun formed and may have played a vital role in the formation of life.

Researchers from the US and Japan have uncovered the origins of a great schism that is theorised to have separated the solar system shortly after the Sun firstly ignited. As is fitting for scientists from the University of Colorado Boulder, this ‘Great Divide’ has been compared to the Rocky mountains.

Just as the Rocky Mountains form a divide between East and West in the US, in space, the Great Divide separates planets like Jupiter and Saturn from Earth and Mars.

Whereas this geological barrier — which runs through Colorado, Wyoming, New Mexico and Montana — divides the east and west sides of North America, its altogether more cosmic counterpart separates the terrestrial planets — like Earth and Mars — from the Jovians — such as Jupiter and Saturn. But, this divide is far more than arbitrary, the planets on either side of the Great Divide are composed of radically different materials. The team believe that organic molecules that scaled this divide, were ultimately responsible for the formation of life on Earth.

“The question is: How do you create this compositional dichotomy?” asks Ramon Brasser, lead author of a paper published in Nature Astronomy. The researcher at the Earth-Life Science Institute (ELSI) at the Tokyo Institute of Technology in Japan, continues: “How do you ensure that material from the inner and outer solar system didn’t mix from very early on in its history?”

Along with the paper’s co-author, Stephen Mojzsis, a professor in CU Boulder’s Department of Geological Sciences, Brasser believes he may have the answer. And, as implied above, it may well have important ramifications for the origin of life on Earth.

The duo of researchers believes that the divide was created by a ring-like structure that formed a disc around our young star. This partition separated the early solar-system into two parts. As such it altered the course of evolution of the planets and other bodies such as asteroids — and may have even affected the history of life on Earth.

“The most likely explanation for that compositional difference is that it emerged from an intrinsic structure of this disk of gas and dust,” Mojzsis says. He also notes that this ‘Great Divide’ — a term he and his collaborator coined — looks pretty insignificant today. In fact, it is represented by no more than a band of empty space near Jupiter and beyond the asteroid belt.

The empty space around Jupiter — pictured here by Juno — gave the researchers their first clue as to the existence of the Great Divide in the solar systems distant past. (NASA Jet Propulsion Laboratory/Southwest Research Institute/Malin Space Science Systems)

This band can still be physically traced through the solar system in the relative concentrations of organic molecules — molecules comprised of elements like hydrogen, oxygen, nitrogen and carbon. Using the Great Divide as a starting point and moving inward toward the Sun, an astronomer would note most planets hold low-abundances of organic molecules. Should the astronomer travel in the opposite direction, however, she would observe more bodies in this distant part of the solar system made of carbon-rich matter.

This dichotomy came as a surprise to the researchers who first uncovered it, explains Mojazsis. And, since it was discovered, scientists had always assumed that the disparity was caused by the gravitational influence of Jupiter. They believed that the gas-giant provided a gravitational barrier that blocked dust and larger clumps of matter from making its way towards the sun.

Sceptical of this assumption, Mojzsis and Brasser used a series of computer simulations to model Jupiter’s role in the solar system as it evolved. These simulations indicated to the duo that even as massive as Jupiter is, it still isn’t large enough to completely stem the flow of rocky material towards the Sun, especially in the early stages of its formation.

“We banged our head against the wall,” Brasser adds. “If Jupiter wasn’t the agent responsible for creating and maintaining that compositional dichotomy, what else could be?”

The answer, they discovered, was hiding in plain sight.