But the question still remains, why aren't the planetary orbits perfectly circular?

但问题仍然存在，为什么行星的轨道不是完美的圆形？

His discovery solved a lot of mathematical problems that astronomers were having with planetary orbit measurements.

他的发现解决了很多天文学家在计算行星轨道时遇到的问题。

In the 17th century, Johannes Kepler theorized cosmic musical harmonies to explain the nature of planetary orbits.

在17世纪，约翰尼斯·开普勒 将宇宙周期理论化来解释行星轨道的本质。

In calculating the planetary orbits he had merely applied two natural laws which Galileo had already proposed.

在计算行星轨道时，他仅仅应用了伽利略已经提出的两条自然法则。

He was the one who provided the final description of the solar system and the planetary orbits.

他是对太阳系和行星轨道进行最终描述的人。

This was until Kepler came in and laid down important laws pertaining to planetary motion, with the first one being that planetary orbits are elliptical.

直到开普勒的出现，他提出了关于行星运动的重要定律，第一个定律是行星轨道是椭圆的。

The investigation of astronomy soon led  to advances in physics. For example, German astronomer Johannes Kepler attempted an  explanation of planetary orbits around the sun.

天文学的研究很快导致了物理学的进步。 例如，德国天文学家约翰内斯·开普勒试图解释行星绕太阳运行的轨道。

His original motivation was the problem of how to get spacecraft sent to other worlds to slow down fast enough to land or enter planetary orbit.

他最初的动机是研究如何让送往其他星球的宇宙飞船以足够快的速度减速着陆或进入行星轨道。

In the 17th century, Johannes Kepler and Isaac Newton laid the mathematical groundwork of planetary orbits, and that in turn made it possible, in theory, to get the distances to the planets.

在17世纪，约翰内斯·开普勒和艾萨克·牛顿为行星公转轨道的研究奠定了数学基础，这反过来又使得从理论上得到行星的距离成为可能。

A lot of people have heard of an astronomer called Johannes Kepler and how he proved that planetary orbits are elliptical and that the sun is not at the center of the orbit.

很多人听说过天文学家约翰内斯·开普勒以及他如何证明行星轨道是椭圆的，以及太阳不是轨道的中心。