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SALT LAKE CITY -- Our local planetary family wasn't always the sunny stalwart of stability that it is now. When it was only 600 million years old, there was some conflict, some fighting between the older siblings, and ultimately our solar system lost a gas giant similar to Jupiter.
Or at least that's what a few astrophysicists are suggesting. The solar system didn't always look like this, and the fact that it does is actually pretty striking. Our solar system is far more spaced out than most of the typical system. Something happened a long time ago that put the planets I the place that they are now, some kind of serious instability.
"We have all sorts of clues about the early evolution of the solar system," says author Dr. David Nesvorny of the Southwest Research Institute. "They come from the analysis of the trans-Neptunian population of small bodies known as the Kuiper Belt, and from the lunar cratering record."
Given all this analysis, a theory began to emerge that Jupiter must have moved very quickly to its current orbit at some point. Only, every model suggested that if Jupiter "jumped" into its current orbit, it would have ejected one of the other gas giants out into space, dooming it to wander the universe lonely and cold like the family black sheep, never to return. But clearly that never happened, since the other gas giants are, you know, still there.
Nesvorny attacked the problem by running over 8,000 computer simulations with varying starting positions for the planets, and varying numbers of planets. What emerged was that an end point like our current solar system could only be achieved if there was a large, Jupiter-like gas giant that was spit out of the solar system, protecting both the inner planets, and putting Jupiter where it is now.
An end point like our current solar system could only be achieved if there was a large, Jupiter-like gas giant that was spit out of the solar system, protecting both the inner planets, and putting Jupiter where it is now.
"The possibility that the solar system had more than four giant planets initially, and ejected some, appears to be conceivable in view of the recent discovery of a large number of free-floating planets in interstellar space, indicating the planet ejection process could be a common occurrence," said Nesvorny.
Planets like Jupiter have a nasty habit of moving toward their star as time goes on, which would have been devastating for the inner planets, especially earth. Juperter would have scattered them all around, possibly ejecting them entirely. Life would never have formed.
But, thanks to the proposed gas giant, the family black sheep who took one for the team, so to speak, we are at the orbit we currently inhabit.
The theory is bolstered by the discovery over the last few years of many wandering planets, floating about the Milky Way, unattached to any solar system. There could be millions of these kinds of planets, and getting kicked out of the house, as it were, may not be such a rare occurrence.
Email: [dnewlin@ksl.com](<mailto: dnewlin@ksl.com>)
