The Pole Star and Changing Sky-Views
If you spend some time stargazing one night, you will see the stars move across the sky. Really, the stars just seem like they're moving; it is actually the Earth that moves, by spinning on its axis. As the Earth spins, its "nighttime" side slowly turns towards different portions of the sky, so different stars are visible at different times. (Of course, the other side of the Earth is facing the Sun, and daytime.) It takes the Earth 4 minutes short of 24 hours to get back to the same spot of nighttime sky, and the same constellations; so each star is said to set 4 minutes earlier than it did the previous night.
When a star comes up in view above the horizon, we say that it is rising; when it goes down and out of view below the horizon, we sat that it is setting. Just like the Sun and the Moon, the stars rise in the east and set in the west. The Pole Star stays virtually in the same spot in the sky, more or less at the pole of the sky; all the other stars seem to revolve around it in circles. On pages 22-23 of Rey's The Stars, there is a great activity using an umbrella to demonstrate the way the stars seem to rotate around the Pole Star. You would designate the tip of the umbrella as the Pole Star, and draw the constellations around it, on the fabric of the umbrella. If you can find a really large umbrella, you can have students walk around underneath it, to show how the stars actually remain fixed; in this case, the walking student would represent the Earth.
Six constellations are located close to the pole, and as such will always appear above the horizon; that means they are always visible. Called circumpolar constellations, they are Great Bear, Little Bear, Cassiopeia, Cepheus, Dragon, and Giraffe.
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