Both models explain it simply, and even a simple model with circular orbits explains it easily. Normally, as the planets rotate round the Sun, they appear to move along the ecliptic from west to east. But in the short period around opposition, when the planets are opposite the Sun in our sky, and we are closest to them, they appear to move east to west because they are going round more slowly than us - we are overtaking them. That is retrograde motion.
It really is the only rational model that does. For years, epicycles were built in to explain retrograde motion, but there was no explanation of why the planets would loop.
This model is easily shown by having a group of people at different distances from a center walk around that center using the velocity calculated by Kepler. If done at dusk, using small lamps, you can actually see retrograde motion in the outer "planets." (lamps or LEDs or whatever).
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retrograde motion
retrograde motion
The retrograde motion of the planets is well modelled by both the Ptolemaic system and the Copernican system, and by the other models. But the Copernican system explains it more simply because, for example, Mars's retrograde motion is caused simply when Mars is overtaken by the Earth, which goes more quickly round the Sun. Thus an observer on the Earth sees Mars appearing to go 'backwards' on the ecliptic around the time of closest approach (opposition). This can be easily demonstrated by assuming simple circular orbits.
All the models explain retrograde motion because it is such an obvious phenomenon. In Copernicus's model an outer planet goes into retrograde motion when the inner planet overtakes it so that it appears from the inner planet to be going backwards along the ecliptic.
Venus and Uranus have retrograde rotation.There are other meanings of retrograde motion, but retrograde rotation fits the question best.
retrograde motion
Retrograde motion important in astronomy because it helped to explain that the planets revolved around the Sun. Retrograde motion is the ability of some objects to rotate in a direction that is opposite what is expected.
retrograde motion
Earths faster motion makes Mars appear to be going backwards, the backwards motion, in fact, is what caused retrograde motion. --Ptloemy used Epicycles to explain how geocentrical models worked.
retrograde motion
All the models explain retrograde motion because it is such an obvious phenomenon. In Copernicus's model an outer planet goes into retrograde motion when the inner planet overtakes it so that it appears from the inner planet to be going backwards along the ecliptic.
The retrograde motion of the planets is well modelled by both the Ptolemaic system and the Copernican system, and by the other models. But the Copernican system explains it more simply because, for example, Mars's retrograde motion is caused simply when Mars is overtaken by the Earth, which goes more quickly round the Sun. Thus an observer on the Earth sees Mars appearing to go 'backwards' on the ecliptic around the time of closest approach (opposition). This can be easily demonstrated by assuming simple circular orbits.
Retrograde motion is motion in the opposite direction. In the case of celestial bodies, such motion may be real, defined by the inherent rotation or orbit of the body, or apparent, as seen in the skies from Earth.
Venus and Uranus have retrograde rotation.There are other meanings of retrograde motion, but retrograde rotation fits the question best.
KEPLER
Retrograde motion describes something by definition. It is not and has never been a theory.
Prograde motion is a counter-clockwise motion or west to east, retrograde motion is clockwise motion or east to west.