2.5: Note on Earth's Rotation

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You can demonstrate that the rotation is west to east by using an apple or some other fruit to represent the Earth. Hold it with the stem vertical--that would be the axis of the Earth, north pole on top--and mark two points in the northern half --- New York and slightly clockwise from it, (= westward) San Francisco. You can use a lamp as your “Sun," or imagine having a lamp somewhere nearby.

When it is noon in New York, the Sun is almost overhead above “New York," but it is still only 9 in the morning in “San Francisco." Three hours later, the Earth has rotated and now it is noon at “San Francisco," with the Sun close to overhead. To get to this position, San Francisco must rotate to the position New York was in--from west to east.