Astronomy Fundamentals

Medieval Andrenaissance Astronomy

What is Kepler’s First Law of planetary motion?

According to Kepler’s First Law, planets, comets, and other solar system objects travel on an elliptical path with the Sun at one focus point. The effect can be subtle or profound; Earth’s orbit, for example, is very nearly circular, whereas the orbit of Pluto is noticeably oblong, and the orbits of most comets are highly elongated.


This is a web preview of the "The Handy Astronomy Answer Book" app. Many features only work on your mobile device. If you like what you see, we hope you will consider buying. Get the App