Kepler's Laws of Planetary Motion Community
Questions, answers and tips from people who use the Kepler's Laws of Planetary Motion. Change orbit size and shape, see equal-area sectors and check the period–distance law..
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This page shows only real posts from real people, so it starts empty. The guide below has the questions people most often have about the Kepler's Laws of Planetary Motion. Pick one to start a thread, or write your own.
From the tool guide: common questions about Kepler's Laws of Planetary Motion
The items below are not posts by community members. They come from the written guide for this tool and are here to get a conversation started. Use “Ask a follow-up” to open a thread about any of them.
What is Kepler's second law?
The line from the star to the planet sweeps out equal areas in equal times, so the planet speeds up near the star.
From the tool guide Ask a follow-upWhat is eccentricity?
A number from 0 (circle) to 1 that says how stretched an ellipse is.
From the tool guide Ask a follow-upKey ideas
- Orbits are ellipses with the star at one focus.
- A line to the star sweeps equal areas in equal times.
- T² is proportional to a³.
- Planets move fastest when closest to the star.
Things to try
- Set e = 0.9 and watch the speed.
- Double a and check the period.
- Turn on equal areas.
Where this is used
Kepler's laws are still used to plan satellite orbits and find exoplanets.
How to ask a question people can answer
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