Science Fair Project:

Star Clock

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Do the stars themselves move?

You probably know that the rotation of the Earth makes it sunny for about half the day and dark for the other half. Of course, the amount of light and darkness depends on the time of the year. Day and night happen because the Earth rotates on an axis that runs through the north and south poles. Sometimes the part of the earth you’re standing on faces the sun, and sometimes it doesn’t. This is why the sun appears to rise and set—but the sun isn’t actually moving.

Now, let’s talk about what happens in the night sky! The same apparent motion happens to the stars at night. The earth spins, and this makes the stars appear to move from east to west in what is called a diurnal circle—the apparent (not real) movement of the stars around the earth. For example, the Big Dipper constellation appears to move around the poles in what’s called circumpolar motion. If you watch long enough, the constellation will seem to travel around Polaris, the North Star. Exactly where the constellations appear to be in the sky depends on your latitude, or how far north or south you are on the earth.

Author: Tricia Edgar
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