Further investigation, however, caused the Sphere Observer to realize that he does not experience the days because the Sun is rotating around the Earth, but because the Earth rotates uniformly around its own axis.

Note 6 The earth's axis goes through the centre of gravity of the Earth. The points where the earth's axis is penetrates the earth's surface are the geographic north and south poles. The plane perpendicular to the earth’s axis passing through the centre of the Earth is called the equator plane. The equator is where the equator plane intersects the earth's surface.

Because the periodicity of Earth's rotation is set to one day, we know that each point on the earth’s surface is constantly altering its distance to the Sun, again and again, every day. Regardless of the position of the Earth's axis of rotation with respect to a stationary Sun, or vice versa, regardless of the angle of the plane of the circular motion of the Sun on the rotational axis of a stationary Earth, each day would have exactly the same pattern. Either way, every point on the Earth’s surface would take the same position relative to the Sun at the same point in time of each day. In this case, this movement is called a uniform movement in the West and it makes no difference if you say that the Earth rotates relative to a stationary Sun, or conversely, the Sun revolves around a stationary Earth.


However, the uniform rotation of the Earth does not pose a problem if the Sun is motionless. In that case, it does not matter whether you say that the Earth rotates uniformly around its own axis relative to a stationary Sun or vice versa, that the Sun circles around a stationary Earth. That is relative. So one can say it as one sees fit.



Frame of reference with circular path of the Sun

In the reference frame, you can therefore regard the vertical circle as the circular path of the Sun. But be aware:

Because the Earth actually does rotate, Earth's stagnation here applies to any point on its surface. And because every point on the surface of a sphere is by definition central, it is the point where the Sphere Observator is sitting in the frame of reference. I call this circle-centre combination in the frame of reference the "solar arc" (see in the illustration).

 

Continue to: 2.3. Frame of reference rotating Earth around moving Sun

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