![]() All of the planets move around the Sun in a direct (eastward) direction, but three of them (Venus, Uranus and Pluto) rotate in a retrograde (westward) direction, and are said to have a retrograde rotation. Retrograde rotation: This is a rotational motion which is backwards relative to the orbital motion that an object has. No planet has a retrograde orbital motion, but some of the moons of the outer planets move backwards relative to the general motion of the other moons of those planets, and many comets have retrograde revolution. Retrograde revolution: This refers to an orbital motion which is really backwards relative to normal orbital motions. In this "retrograde" motion, neither planet is actually moving backwards it only appears that way during the time that one laps the other. Both planets move in a direct (eastward) motion around the Sun, but the planet with the inside (smaller) orbit moves faster than the planet on the outside (larger) orbit, and when it passes the slower-moving planet, each sees the other one as apparently moving backwards relative to its usual motion around the sky. Retrograde motion: The most commonly discussed "retrograde" motion is the apparent backward motion of a planet caused by its being lapped by another planet, or vice-versa. There are three types of retrograde motion commonly referred to in astronomy: Motions in this direction are referred to as direct motions, while motions in the opposite direction are referred to as retrograde. Most of the rotational and orbital motions in the solar system are in the same "eastward" direction.
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |