The universe is huge. It seems to have no end. 深邃宇宙，浩瀚无垠。
People who study the universe find out more about it all the time. （醉心于）研究宇宙的人们总能不断有新的发现。
Until 2006, students were taught that our solar system had nine planets that moved around our Sun. 直到2006年以前，学生们还被灌输这样一种思想：有九大行星围着太阳转。
Among them, Mercury come: Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.这九大行星在水星之后依次是：金星、地球、火星、木星、土星、天王星、海王星、冥王星。
In August 2006, scientists declared that Pluto is a dwarf planet, which means it is not an ordinary planet. 2006年8月，科学家宣布冥王星只是个矮行星，也就是说，它并不是一颗严格意义上的行星。
So in fact there are only eight planets in the solar system! 所以实际上太阳系只有八大行星！
Pluto is not the only dwarf planet in the solar system. 冥王星并不是太阳系中唯一的矮行星。
Earlier in 2005, American scientists discovered a dwarf planet. 早在2005年，美国科学家就发现了一颗矮行星。
This dwarf planet is further from the Sun than Pluto. 这颗矮行星与太阳的距离比冥王星还要远。
It was given a new name ?Eris‘ in September 2006. 2006年9月，这颗矮行星被命名为阋神星。
We know that Pluto is very cold and consists mostly of ice and rock. 我们都知道：冥王星上气温很低，主要由冰块和岩石构成。
Think how cold Eris must be! 你不妨想象一下阋神星有多冷！
Can anything live on dwarf planets? Is there life on any of the planets? 矮行星上能住人吗？行星上会有生命存在吗？
Let‘s look at the two planets closest to Earth – Mars and Venus. 让我们看看最靠近地球的两颗行星——火星和金星。
Because they are the closest, we have studied them more, so we have more evidence about them, 因为这两颗行星距离地球最近，我们对它们的研究更深入，所以我们有更多关于这两颗行星的证据资料。
Satellites have photographed Mars and Venus from space. 卫星已经从太空中拍摄了火星和金星的照片。
Some satellites have landed on Mars and Venus, and collected evidence of what they are like.有些卫星已经在火星和金星上着陆，并且收集了足够的信息来说明它们是什么样的。