How do we know that the Earth is a smaller ball turning around one of those stars, the Sun?
我们怎么知道地球是一个更小的球，绕着其中一颗恒星——太阳转呢？
2
The earth would be a frozen ball if it were not for the radiant heat of the sun.
要是没有太阳的辐射热，地球将会是一个冰冻的球体。
《柯林斯英汉双解大词典》
3
All the gravity of all the mass in the cosmos should have been pulling the universe back inward, just as gravity pulls a ball back down to Earth after it's been thrown into the air.