Before astronomers began to find planets — many, many planets — orbiting Suns other than ours, the scientific consensus was that if other solar systems were ever found they would probably look much like ours. That would mean small, rocky planets closest to the Sun and large gaseous planets further out.
That assumption crash and burned with the discovery of the first discovery of an exoplanet orbiting a star — 51 Peg. It was a hot, Jupiter-sized planet that circled its Sun in four days.
That planetary rude awakening was followed by many others, including the discovery of many rocky planets much larger than those in our system which came to be called super-Earths. And equally common are gaseous planets quite a bit smaller than any near us, given the name sub-Neptunes.
Many papers have been written theorizing why there are no super-Earth or sub-Neptunes in our solar system. And now astrophysicist Stephen Kane of the University of California, Riverside has taken the debate another direction by asking this question: What would happen to our solar system planets if a super-Earth or sub-Neptune was present?
The results of his dynamic computer simulations are not pretty: the orbits of many of our planets would change substantially and that would ultimately result in some being kicked out of the solar system forever. The forces of orbit-transforming gravity set loose by the addition of a super-Earth are strong indeed.
Let’s go back to our actual solar system for some context.
The gap in size between the size of our terrestrial planets and giant gas planets is great. The largest terrestrial planet is Earth, and the smallest gas giant is Neptune, which is four times wider and 17 times more massive than Earth.… Read more