Retrograde Motion of Mars

Mars initially moves eastwards from February to June, then reverses its path and moves backwards in July, August, and September. It changes its direction of motion once again and continues its forward motion from October onwards.

Ancient astronomers recorded the retrograde motion of visible planets and tried to explain the motion. According to Aristotle, the other planets and the Sun move around the Earth in circular orbits. Ptolemy introduced the concept of 'epicycle' in his geocentric model to explain retrograde motion.

According to Aristotle, the other planets and the Sun move around the Earth in circular orbits.

<p>Ptolemy introduced the concept of 'epicycle' in his geocentric model. According to this theory, while the planet orbited the Earth, it also underwent another circular motion termed as 'epicycle'. A combination of epicycle and circular motion around the Earth gave rise to retrograde motion of the planets with respect to Earth.</p> Signup and view all the answers

<p>The challenge was that if the planets moved in circular orbits around the Earth, it was not known how the planet could reverse its motion for a brief interval.</p> Signup and view all the answers