VIDEO: 6 planet system formation

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A simulation of how a 6 planet system forms. The simulation starts off with 900 Mars sized protoplanets orbiting a sun like star within a distance of 1 AU.

WARNING: This simulation does not have scientific value and is merely created for illustrative purposes. Object sizes are exaggerated to increase the chances of them hitting each other. This allows the planets to form in a short amount of time. Simulations in this program have different outcomes if the speed of time changes thus showing that they are likely not accurate.

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Software used: Link

More about planets around other stars: Link


The simulation has been created such that all objects start off orbiting the star in circular orbits. All objects orbit within a range of 0.16 AU to 0.68 AU from the star. Each object is 10% the mass of the Earth (similar mass to the planet Mars). As the objects affect each other with gravity, their orbits become more eccentric. Eventually, they start merging with each other.

At one point, one of the objects appears to have entered into a retrograde orbit that was highly eccentric. This object eventually hit and merged with what became the second innermost planet. This sent it into an eccentric orbit that took it close to the planet closest to the star. Eventually, the planet’s orbit became more circular due to the gravity of other planets.

As the simulation progressed, the two innermost planets were the first to settle into relatively stable orbits. Three of the planets farther out followed suit awhile later. The outermost planet took the longest time to settle into a stable orbit. For a long time, it shared a similar orbit with another object. Both objects affect each other via gravity until they both merge. This caused the outermost planet to end up in a highly eccentric orbit.

Final planet masses of the 6 planet system. Credit: Junying Chen

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