Physics · Study 017
Orbit Sandbox
Click anywhere to launch a planet around a star and watch gravity bend its path into an ellipse, a slingshot or a crash.
What you're looking at
Every planet feels one force, an inverse square pull toward the star, and is advanced in small steps that conserve energy well over many laps. New planets start with roughly circular speed plus some random error, so most settle into ellipses, some escape, and a few fall in.
The idea behind it
Kepler worked out from Tycho Brahe's observations that orbits are ellipses with the Sun at one focus and that planets speed up when they are closer. Newton later showed that both facts follow from a single law of attraction. You can see the speed change here in how far apart the trail dots are.
Try this
Click or tap to add a planet at that distance. Close in they race, far out they crawl.
