What moon revolves around its planet in a retrograde orbit?
Titan is not one of them, but there are several moons that revolve in retrograde orbits.
The most well-known is probably Triton, the largest moon of Neptune.
Triton is the only large moon in the solar system to have retrograde motion.
Retrograde orbit is when an an object, like a satellite, goes around another object, like a planet, in the direction opposite the second object's rotation. For example, Neptune's moon Triton goes around Neptune with a retrograde orbit. Rather than orbiting around Neptune in the same counter-clockwise direction Neptune rotates in, Triton orbits Neptune in a clockwise direction.
Yes. "Retrograde motion" occurs when the apparent path of a planet through the background of the stars appears to turn backward from its usual direction. The cause is that the Earth and other planets are in orbit around the Sun. The inner planets orbit more quickly than the outer ones. At times in its orbit, the Earth seems to "leap ahead" as it passes the outer planet.
This is nothing as complicated as "models of the universe"... it is a geometric phenomenon. For example, if an outer planet - outside the Earth's orbit - is retrograde, that simply means that Earth is overtaking that planet; temporary the planet seems to go "backwards". The main movement of planets is from West to East; but for part of each orbit, each planet will have an (apparent) movement from East to West - then it…
Planet retrograde is when the planet appears, from the Earth point of view, to be orbiting opposite from its normal direction around the sun. Basically, it looks like its going backwards. It usually occurs when Earth overtakes a planet in its orbit. This video here at the link below shows a good example of what retrograde looks like. The top part of the video shows the movement we see from Earth while the bottom shows…
A retrograde motion of an OUTER planet happens when Earths orbit catches up with and overtakes the planet as Earth orbits the Sun. For Jupiter it is observed to be in retrograde (moving backwards as measured against the fixed stars) motion for 121 days a year. NOTE Jupiter is not actually moving backwards, it just appears to.