The ancient Greeks believed that what we called the solar system was in fact the entire universe, and that the universe was geocentric.(古希臘人堅信，我們所謂的太陽系實際上就是整個宇宙，并且宇宙以地球為中心。)

The space probe, Voyager I, launched in 1977, had sent back spectacular images of Jupiter and Saturn and then soared out of the Solar System on a one-way mission to the stars.(1977年發(fā)射的“旅行者一號”太空探測器發(fā)回了木星和土星的壯觀圖像，然后飛出太陽系，執(zhí)行前往恒星的單程任務(wù)。)

The spacecraft will enable scientists to study some dark corners of the solar system.(太空船使得科學家可以研究太陽系中一些不為人知的角落。)

The solar system also has two analogous classes of objects, smaller than planets—namely, asteroids and comets.(太陽系也有兩類類似的物體，比行星還小——即小行星和彗星。)

That makes it the biggest known crater in our solar system and it may well be the oldest.(這使它成為太陽系中已知最大的隕石坑，也可能是最古老的隕石坑。)

Why do scientists think something could be hidden beyond the edge of our solar system?(為什么科學家認為某些東西可能隱藏在我們太陽系的邊緣之外？)

For more than 300 years, we thought Saturn was the only body in the solar system with rings.(在300多年的時間里，我們一直認為土星是太陽系唯一擁有光環(huán)的天體。)

The orderly nature of our solar system leads most astronomers to conclude that the planets formed at essentially the same time and from the same material as the Sun.(我們太陽系的有序特性使大多數(shù)天文學家得出結(jié)論，這些行星基本上在同一時間形成，且物質(zhì)來源和太陽的一樣。)

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，是太陽系的四個重量級。但曾經(jīng)存在第五個行星嗎？)

They're basically made up of debris left over from the origin of the solar system.(它們基本上是由太陽系起源時遺留下來的碎片組成的。)