The revolution of the earth around the sun is how we define the year.
Giant Jupiter has lots of spin, turning once on its axis every 10 hours, while Venus takes 243 days to spin once. There are no rules that govern the rotation rates of the planets, it all depends on how much 'spin' was in the original material that went into forming each one. We further divide this period of time into 24 hours, each of which is divided into 60 minutes, each of which is broken into 60 seconds. The time it takes the earth to rotate from noon until the next noon we define as one day. The top-like rotation of the earth on its axis is how we define the day. Second, the earth revolves around the sun, like a tetherball at the end of a string going around the center pole. First, the earth rotates on its axis, like a spinning top. There are two that specifically interest us. Actually, several different motions all at once. This brings up the question of how we define the time intervals we measure. Looking at the numbers above, you'll immediately notice that you are different ages on the different planets.
