Number 21
Date Jan. 1st 2006
Previous Ferret
Next Barrel - Part 3

Kepler is the 21st xkcd comic.



Animated gif of Kepler's second law. Click to view the animation.

This comic is a reference to Kepler's laws of planetary motion, which were discovered by Johannes Kepler in the early 1600s. It specifically refers to the second law:

A line joining a planet and the Sun sweeps out equal areas during equal intervals of time.

The joke is that the store's janitor also sweeps equal areas in equal amounts of time.

Mouseover textEdit

"Science joke. You should probably just move along."

See alsoEdit

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