Earth was made by Jupiter clattering through the universe and destroying small planets

Theory suggests that there are few other planets like ours

Andrew Griffin
Tuesday 24 March 2015 14:26
Jupiter, visible from Earth with the naked eye next to our moon
Jupiter, visible from Earth with the naked eye next to our moon

Our solar system is hugely different to others — and it got that way because Jupiter soared through the planet shortly after it was born, causing chaos in space and helping to create the Earth.

Most other planetary systems have giant planets close to the central star — much closer than the sun is to Mercury, its closest neighbour. The reason that our solar system is different has long been a mystery to scientists, but a new paper proposes a theory as to how it got formed.

Jupiter was pulled towards the sun when it was formed, according to a paper published in Proceedings of the National Academy of Sciences. As it moved through space, it acted like a wrecking ball, destroying small planets before going back to its current orbit, according to the paper written by Gregory Laughlin and Konstantin Batygin.

The gravitational upset caused by Jupiter’s quick sweep through space would have swept smaller planets and other bodies into small, overlapping orbits. They would then have collided with each other and been smashed into pieces, according to the theory.

"It's the same thing we worry about if satellites were to be destroyed in low-Earth orbit. Their fragments would start smashing into other satellites and you'd risk a chain reaction of collisions. Our work indicates that Jupiter would have created just such a collisional cascade in the inner solar system," Laughlin said.

The debris that came out of the collisions would have been dragged into the sun and destroyed, the theory argues.

As well as explaining the huge hole where scientists would expect to find planets, the theory also accounts for how the Earth came to be the way it is. The rocky planets like Earth and Mars were formed later than the other planets, when the material was in short supply.

Those planets, which also include Mercury and Venus, are much younger, smaller and have thinner atmospheres than would be expected in similar solar systems, according to Laughlin. They are the same conditions that appear to have allowed life to flourish on our planet.

But the theory also means that planets like ours are probably unusual. "One of the predictions of our theory is that truly Earth-like planets, with solid surfaces and modest atmospheric pressures, are rare," he said.

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