大学英语阅读，求解

Question

The earth is not the only body that travels around
the sun. With it are eight other planets (行星), fellow members of the sun's
family.
Two of them are nearer while the other six are farther from the sun than the
earth is. The farther they are, the longer trips they make around the sun.
People noticed long ago that these traveling bodies moved around in the sky in
fixed paths. It is a force called gravity (重力) that holds them in their paths.
We know that every little bit of matter in the universe (宇宙) pulls upon every
other bit of matter. Because the sun is so large, the pulling between the sun
and the planets must be very great. If it were not for this pulling, the planets
would fly off into space. In the same way there exists a pull between the earth
and the moon, which keeps the moon traveling in its orbit (轨道) around our
planet, the earth. Gravity holds you to the earth's surface, and pulls the ball
you throw into the air back to it. Of course, the ball also pulls on the larger
earth but the earth is so much larger that the pull is not noticed.
Now remember that large bodies bring to bear a greater pull on any body that
contains less material. But each object in the universe, no matter how small,
pulls on all other objects to some degree.
字数限制，看完的回复下，我会追问题目

Answer 1

地球不是唯一绕着太阳转的星球，在太阳的家庭中另有8颗行星。
其中两颗离得比地球离太阳很近，而其他的六颗比地球离太阳还要远。他们离地球越远，他们绕行太阳的时间越久。人们很久以前发现这些球体在一个不断被修复得轨道中运行。这是一种被称为重力的力量在维持他们的轨道。我们知道宇宙中的所有事物都互相吸引着（万有引力）。由于太阳的体积太大，太阳与这些行星之间的引力一定很巨大。如果没有这些引力，行星将会飞走。同理，地球和月亮之间存在相同的引力，这是保持月球绕着我们的地球运转的原因。重力使你保持在地球表面上，把你扔向空中的球拉回来。当然，这个球也会对地球有引力，只是地球太大，导致来自球的引力可以被忽略。现在记住这点，大的物体需要承受更大的来自其他较小物体的引力。但是每个在宇宙中的物体，不论多小，总会对其他物体产生引力。

Answer 2

后文呢，讲了个万有引力的事情嘛本回答被网友采纳