To evolve into our current solar system, the original version probably had a fifth gas giant, computer simulations indicate. John Matson reports.

計算機模擬表明，要演變成我們目前的太陽系，最初的形式可能存在第五個巨大的氣體行星。John Matson報道。

Jupiter, Saturn, Uranus and Neptune. Those are the gas giants, the four heavyweights of the solar system. But was there once a fifth?

木星，土星，天王星和海王星。這些都是氣體行星，太陽系的四個重量級。但曾經存在第五個行星嗎？

Maybe so, says a new study by David Nesvorny of the Southwest Research Institute in Boulder, Colorado. He used computer simulations to explore what the solar system may have looked like some four billion years ago.

也許是這樣，位于科羅拉多，博爾德市的西南研究所的David Nesvorny對這項新研究如是說。他利用電腦模擬來重現太陽系四十億年前可能的樣子。

Early on, the giant planets migrated, tugged on each other and generally shook things up before settling into their current orbits. So the simulation tested different initial arrangements of planets to see which would evolve into the solar system we know so well.

初期，在這些巨大行星進入現在的軌道之前，他們會遷移，彼此牽引并且震蕩。所以，該模擬測試了行星各種不同的開始布局，以便發現哪一種布局可以演變成我們所熟知的太陽系。

With just four giant planets at the outset, the solar system hardly ever wound up looking like ours. But with a fifth planet, the simulations produced familiar solar systems 10 times more often. [David Nesvorny, "Young Solar System's Fifth Giant Planet?" on arXiv.org]

開始只有4個巨大行星時，太陽系并不像現在這樣有生氣。但是加入第五個行星后，模擬10多次都重新了我們所熟知的太陽系。 [David Nesvorny, "Young Solar System's Fifth Giant Planet?" on arXiv.org]

So what happened to the extra planet? It would have run afoul of Jupiter and been chucked into interstellar space. Astronomers have recently discovered that the galaxy is filled with such orphaned planets. Billions of them. So, if an extra planet did get cast out of the solar system, at least it has plenty of company.

這個特別的行星發生了什么？他可能與木星運行相沖突并被拋到了星際空間。天文學家最近發現星際間充滿了這樣的孤立行星，億萬多的行星。所以，如果這個特別的行星的確被拋出了太陽系，至少他有很多的同伴。
—John Matson