Rotation
The movement of the earth spinning around itself on its axis is called rotation. The imaginary line around which the earth spins or rotates is called the axis of the earth. The earth’s axis is at an angle of 66 ½ to the orbital plane, which is the plane formed by the earth’s orbit. If a vertical line is drawn perpendicular to the orbital plane, the axis forms an angle of 23 ½. This is called the earth’s angle of inclination.   The earth takes 24 hours to complete one rotation around itself. While the earth rotates, the sun remains stationary. As the earth rotates, only half of it faces the sun at any time, while the other half faces away from the sun. It is daytime in the part that faces the sun, while it is night in the other half. The circle that divides the day and night on the globe is called the circle of illumination. The earth spins from west to east. One side of the earth would always face the sun and would get extremely hot, while the other side would always have night and would become too cold. Thus, night and day are caused because of the earth’s rotation.

#### Summary

The movement of the earth spinning around itself on its axis is called rotation. The imaginary line around which the earth spins or rotates is called the axis of the earth. The earth’s axis is at an angle of 66 ½ to the orbital plane, which is the plane formed by the earth’s orbit. If a vertical line is drawn perpendicular to the orbital plane, the axis forms an angle of 23 ½. This is called the earth’s angle of inclination.   The earth takes 24 hours to complete one rotation around itself. While the earth rotates, the sun remains stationary. As the earth rotates, only half of it faces the sun at any time, while the other half faces away from the sun. It is daytime in the part that faces the sun, while it is night in the other half. The circle that divides the day and night on the globe is called the circle of illumination. The earth spins from west to east. One side of the earth would always face the sun and would get extremely hot, while the other side would always have night and would become too cold. Thus, night and day are caused because of the earth’s rotation.

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