The ancient Greeks believed that what we called the solar system was in fact the entire universe, and that the universe was geocentric.(古希腊人坚信，我们所谓的太阳系实际上就是整个宇宙，并且宇宙以地球为中心。)
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年发射的“旅行者一号”太空探测器发回了木星和土星的壮观图像，然后飞出太阳系，执行前往恒星的单程任务。)
The spacecraft will enable scientists to study some dark corners of the solar system.(太空船使得科学家可以研究太阳系中一些不为人知的角落。)
The solar system also has two analogous classes of objects, smaller than planets—namely, asteroids and comets.(太阳系也有两类类似的物体，比行星还小——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.(这使它成为太阳系中已知最大的陨石坑，也可能是最古老的陨石坑。)
Why do scientists think something could be hidden beyond the edge of our solar system?(为什么科学家认为某些东西可能隐藏在我们太阳系的边缘之外？)
For more than 300 years, we thought Saturn was the only body in the solar system with rings.(在300多年的时间里，我们一直认为土星是太阳系唯一拥有光环的天体。)
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.(我们太阳系的有序特性使大多数天文学家得出结论，这些行星基本上在同一时间形成，且物质来源和太阳的一样。)
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。这些都是气体行星，是太阳系的四个重量级。但曾经存在第五个行星吗？)
They're basically made up of debris left over from the origin of the solar system.(它们基本上是由太阳系起源时遗留下来的碎片组成的。)
