We all learned about the solar system in school and, apart from one notable demotion of Pluto to the rank of dwarf planet in 2006, things are pretty straight forward in terms of the planets and their orbits.
But we still don’t understand everything about the solar system or how the planets formed.
One experiment at the University of California, Riverside (UCR) took an extreme approach to get to the bottom of the history of our family of planets. They made a new planet with a computer simulation.
The fabricated planet experiment aimed to address two notable gaps in our understanding of planetary science.
First, there is a large gap between the sizes of the planets. The solar system has very large planets – the gas giants – and small planets – the rocky, terrestrial planets like Earth.
Of the terrestrial planets, Earth is the largest. Neptune is the smallest gas giant. But Neptune is four times wider and a whopping 17 times heavier than Earth. “In other star systems there are many planets with masses in that gap. We call them super-Earths,” says UCR astrophysicist Professor Stephen Kane.
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There is also a massive physical gap between the planets – specifically between Mars and Jupiter – the planetary chasm currently holds the asteroid belt, but Kane explains that “planetary scientists often wish there was something in between those two planets. It seems like wasted real estate.”
Some believe the asteroid belt represents the remnants of a planet, referred to as Phaeton, that was smashed up billions of years ago. The total mass of the asteroid belt objects, though, is less than four percent that of Earth’s Moon.
Understanding these gaps in our solar system could give us important insight into the structure of the solar system and how Earth evolved.
Kane and his team filled these gaps by running dynamic computer simulations of a theoretical planet situated between Mars and Jupiter with a range of masses. The simulation then showed how such a planet would effect the orbits of all the other planets.
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The effect of the invented planet was mostly catastrophic for the solar system.
“This fictional planet gives a nudge to Jupiter that is just enough to destabilise everything else,” Kane explains. “Despite many astronomers having wished for this extra planet, it’s a good thing we don’t have it.”
Jupiter’s mass is 318 times that of Earth. In fact, Jupiter far outweighs all the other planets combined!
So the addition of a super-Earth in our star system which agitates Jupiter even slightly will have profound consequences for all the other planets.
Here are some ways a super-Earth between Mars and Jupiter could end life:
- A specific mass and orbit relationship for the fictional planet could see its gravitational effects leading to Mercury, Venus and even Earth being ejected from the solar system. It could even destabilise the orbits of Uranus and Neptune, sending them into outer space as well.
- If the super-Earth changed Earth’s orbit, even a little bit, our planet could become far less habitable or even entirely inhospitable for life.
Kane says that a smaller super-Earth directly in between Mars and Jupiter could remain stable, but small deviations in any direction and “things would go poorly.”
Jupiter-like planets, gas giants far from their stars, are found in only 10 percent of planetary star systems. But their role in deciding whether Earth-like planets have stable orbits appears to be significant.
“Our solar system is more finely tuned than I appreciated before. It all works like intricate clock gears. Throw more gears into the mix and it all breaks,” Kane comments.
The research is published in the Planetary Science Journal.