Our sun is a star ,and nine words move round it .Words like these are planets (行星).

But there are other stars ,other suns ,not only thousands of them ,but millions of them .Do you different stars have planets ?We can see the planets round our own sun .But we haven*t seen anymore .The stars are too far away from us .Stars give out (发出)light ,but the planets don*t have any light of their own .So we can*t see them .They are too far ,and too dark.

Still we can tell that some stars have planets .While a big planet goes round,it pulls its star to one side .And sometimes we can see this .Then we know that the star has a planet.

For example ,Barnard*s Star（巴纳德星）is a small red star .And it is the quickest star in the universe .But sometimes it moves slower,and then quicker again .We have known Barnard*s Star for many years ,and now we are sure it has a planet.

太阳是一颗恒星，并有九颗星星环绕着它。这九个星星即是行星。
但是还有数千乃至数百万个其他星星，太阳。你能区分星系包含有行星吗？我们能够看到行星环绕着太阳。但是我们没有见到任何其他的行星。星系离我们太过遥远了。恒星能够发出亮光，但是行星自身不会发光。所以我们看不到它们，它们离我们太远而且太暗了。
然而我们能够区分一些星系拥有行星。当一颗大行星环绕运动时，它会把别的星星拉到另一边。有时我们能够见到这个情形。因此我们知道这个星系拥有行星。
例如，巴纳德星是一颗小红星。它是宇宙中最快的星星。但是有时它会移动的很慢，接着又很快。我们已经了解巴纳德星很多年了，现在我们能够确定它是颗行星。