Retrograde Motion

The temporary apparent backward motion of a planet in the sky, from east to west, caused by the geometry between the Earth and planet. Due to this geometry, only planets that orbit outside the orbit of the Earth are observed to have retrograde motion.

Radio Programs

Loopy Planet A planet gets a little loopy Sunday, April 27, 2014
Jupiter at Opposition Speeding past a bright giant Thursday, August 13, 2009


©2014 The University of Texas McDonald Observatory