In the resulting image (see the repitition), the three periodicities of the Earth relative to the Sun, or the two circle-centre shapes are now represented as follows:

Vertical

• periodicity of the days: uniform circular motion of the Sun around the stationary Sphere Observer at the centre of the earth's surface

• periodicity of the years: uniform circular motion of the Sun around a uniformly rotating earth (dark grey)

Horizontal

• Periodicity of the seasons: Uniform horizontal circular motion on the horizon of the earth's surface

Because of the three periodicities being represented by only two circle-centre shapes, it was necessarily assumed that a uniformly moving Sun was on the vertical circle with respect to a stationary, uniformly rotating Earth in the centre.
In reality, however, the annual movement of the Sun is accelerated, and not only the rotation of the Earth is uniform, but also its translation. So, the image above is incorrect.

Now the previous mistake can be corrected by making the complete frame move uniformly to the north or to the south (see the arrow in the adjoining frame).
This motion will, in this case, always be square with the vertical plane of the frame, which means:

• that the standstill of the uniformly rotating Earth becomes a uniform translation

• that the circular path of the Sun becomes a helix and its motion hybrid. So uniform and accelerated at the same time:

. uniform on behalf of the periodicity of the days

. accelerated for the periodicity of the years

Every Sphere Observer, in the centre of his frame, thus moves uniformly and in an unrestricted way through space, without any forces acting upon him. The Earth’s rotating does not affect him, because the Sphere Observer is by definition central. The Earth then is as it were turning beneath him: He is now in a so-called free fall with respect to the Earth, which is a very modern idea in Western physics (see Note 18).

Note 21 Free fall is the state in which no external force is exerted on a body (object) except for gravity. The acceleration of the body in that case is equal to the acceleration due to gravity. A spacecraft is in free fall from the moment the rocket engine is turned off. If the spaceship has enough speed for an orbit around the earth, it is constantly in free fall without reducing the distance to the ground. The astronauts in the spacecraft are subsequently weightless, because there are no forces exerted on them. This condition can last forever, though a spacecraft, especially when it is in a low orbit around the earth, will fall back to Earth after a few years. (Nl Wikipedia)

In this way, the Frame of Reference of  the Sphere Observer becomes an eastern inertial frame of reference.

Continue to: 3.3. Inertial frame of reference is the ultimate recognition of the initial hypothesis