Why the starry sky as if spinning and why polar star almost motionless? It turns out that the reason for this apparent motion of the stars is in the rotation of the Earth. Just as man, swirling around the room, it seems like the whole room is spinning around it, and we are located on the rotating Earth, we see, as if moving stars.

From the geography know that the imaginary axis around which it rotates the globe, crosses the Earth's surface in two points. These point - North and South geographic poles. If the direction of the earth's axis to continue, it will take place near the North star. That is why the North star seems almost motionless. It is situated at the North pole of the world.

On the southern night sky, which in our Northern hemisphere apparently only partially because of the spherical shape of the Earth, is the second fixed point is the South pole of the world, " which revolves around the southern star. Will now learn more about the apparent daily motion of the stars.

Turn your face to the South side of the horizon and watch the movement of the stars. To these observations it easier to carry out, imagine a semicircle, which passes through the Zenith (the point directly overhead) and the pole of the world. This semicircle intersect with the horizon at the point of the North (near North star) and in the opposite point of the South. This line astronomers call celestial Meridian. It divides the sky into Eastern and Western halves.

Watching the movement of the stars in the southern sky, we note that the star on the left side of the celestial Meridian (i.e., in the Eastern part of the sky), rise above the horizon. After going through the celestial Meridian and once in the Western part of the sky, they begin to go down to the horizon. So, when they passed through the celestial Meridian, at this point they have reached its greatest height above the horizon. Astronomers call the passage of a star in the highest position on the horizon upper culmination of this star.

If you will turn to the North and will monitor the movement of the stars in the Northern sky, you'll notice that the stars passing through the celestial Meridian below the North star, in this moment occupies the lowest position above the horizon. Moving from left to right, they, passing celestial Meridian, begin to rise.

When the star runs through the lowest possible provisions on the horizon, astronomers say that the star is in the lower climax. Thus, if a star passes through the line of celestial Meridian between a pole of the world (or approximately Polar star) and the point of the South, it will be the upper culmination of a star.