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Lecture
12A |
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| Lecture 12A: Java Tips & Techniques |
Kepler's Three Laws of Planetary Motion
Law 2: The straight line joining the Sun and a planet sweeps out equal areas in equal intervals of time.
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When the satellite orbits the Earth in a highly elliptical path, you can readily see how it slows down as it moves far away from the Earth, and how it speeds up as it gets close to the Earth. It's the same effect you get when you throw a ball up into the air. The ball slows down as it climbs to its greatest height, and speeds up as it falls back down.
In the orbit simulation of Kepler's second law, the satellite is joined by a straight line with the center of the Earth. Watch the area swept out by this line. When the satellite is far from the Earth, the line is long and the satellite moves slowly. When the satellite is near the Earth, the line is short and the satellite moves quickly. The length of the line and the speed of the satellite are such that no matter where in its orbit the satellite is, the line sweeps out the same area in any given time interval.
You can click on the yellow part of the bar on the right and, by dragging, enlarge the swept-out area.
Comments to: Observatorium
Curator (curator@rspac.ivv.nasa.gov)
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