Can someone please simplify what retrograde motion is without a long scientific meaning?

I have a science exam on Tuesday next week and i don't understand retrograde motion. can someone please tell me in a few sentences what it is without some loooong scientific hard to understand explanation?Can someone please simplify what retrograde motion is without a long scientific meaning?Retrograde just means "backwards" -- that is, in the opposite from the "normal" direction. In astronomy, it can mean a couple of things:



1. If a planet spins in the opposite direction from the other planets in the solar system, or orbits in the opposite direction from the other planets, it's said to have a retrograde spin or orbit. (Venus, for example, has a retrograde spin. No planet in our system has a retrograde orbit.)



2. "Retrograde" can also describe the _apparent_ motion of a planet through the stars as you watch it night after night. All planets move generally west-to-east through the stars; but occasionally, for a few days or weeks, one will appear to reverse and go east-to-west. They call this backwards motion "retrograde." The planet is not actually reversing its direction in space--it's more of an optical illusion caused by the relative motion of the earth and the planet considered together. Mars exhibits the most prominent retrograde motion of this type. Here's an animation that illustrates the retrograde motion of Mars: (http://www.lasalle.edu/~smithsc/Astronom鈥?/a> )Can someone please simplify what retrograde motion is without a long scientific meaning?Something going the opposite way it's supposed to. It's usually used in reference to planets, all the planets will ideally move in one direction around the sun and their moons will move in one way around them. But sometimes they appear to go the other way, or they actually do go the other way (none of the planets in our system go the wrong way but some comets and moons do) and when they do that we call it retrograde motion.Can someone please simplify what retrograde motion is without a long scientific meaning?If you watch the outer planets (mars to saturn with the naked eye) in the sky night after night, they seem to move towards the east relative to the stars. The stars seem to be fixed in position relative to each other, but the planets move slowly across the sky, appearing in slightly different locations every night.



However, when Earth passes these planets, the planets seem to move slowly towards the west instead of towards the east. This is called retrograde motion. It means they seem to be moving backwards.



Remember, this is slow motion, with the planets only slightly changing position each night. You would need to be charting the positions to notice the retrograde motion. You won't notice it by casual observation.