因此我想告诉你们，一些关于开普勒第二定律的知识。

So, I want to tell you a bit about Kepler's second law of celestial mechanics.

youdao

首先，我想和大家探讨,17世纪开普勒提出的,著名的三定律。

And I first want to discuss with you the three famous laws by Kepler from the early 17th century.

youdao

我在故事中谈到开普勒，不是因为他解释了星球运行规律，而是因为他解释了光如何在透镜中发生折射。正是他首创了focus(焦点)这个词。

He comes into my little story here because it was he, in explaining not how planetary motion worked but how light bent through lenses, it was Kepler who coined the term focus.

youdao