The rotation axis of the earth is the connecting line between the South Pole and the North Pole, which forms a 90-degree angle with the equatorial plane. The rotation axis of the earth is also called the earth axis. Ordinary planets, satellites, etc. There will be rotation, and so will stars.
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The earth axis is the imaginary axis of the earth's rotation. The earth has been rotating around this imaginary axis. Therefore, it is also called the earth's rotation axis. This axis connects the north and south poles through the center of the earth, and the included angle with the earth's orbital plane is 66 34'. The earth's axis is facing the North Star. The plane passing through the center of the earth and perpendicular to the earth axis is called the equatorial plane.
The position of the earth axis in the earth is not fixed, but slightly moves, resulting in a "pole shift". Its extension line is "celestial axis". The two intersections between the earth axis and the ground are "poles". The two intersections between the celestial axis and the celestial sphere are the "celestial poles".