Image: Apparent retrograde motion
Description: Illustration of the apparent retrograde motion of Mars. The apparent retrograde motion is an artifact of mapping the motions of the objects of the solar system in a coordinate system that is itself in accelerated motion. The yellow dot can be thought of as representing the Sun, the blue dot can be thought of as representing Earth, and the red dot can be thought of as representing Mars. In order to make the animation cycle smoothly, the blue dot completes two orbits for every complete orbit of the red dot. In the case of the actual planets, the ratio of orbit times is not 1:2.
Title: Apparent retrograde motion
Credit: http://en.wikipedia.org/wiki/File:Apparent_retrograde_motion.gif
Author: user:cleonis in the english wikipedia
Usage Terms: Creative Commons Attribution-Share Alike 2.5
License: CC BY-SA 2.5
License Link: https://creativecommons.org/licenses/by-sa/2.5
Attribution Required?: Yes
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