What indicates the motion of the Earth?

Answer 1

First you must be aware of your assumptions. It is well known that the Egyptians measured the angle of sunlight on two wells and computed the circumference of the Earth from those measurements. The Chinese did the same thing, but they assumed the Earth was flat and computed the sun's altitude. Both got reproducible results, but one group had a false assumption. This problem comes up in everything you do.

We assume that a body in motion tends to continue in motion at a constant speed in a straight line unless acted upon by a force. We can't prove that is always true, but if it is not then the universe is run by magic and we can never know anything.

Now we hang a pendulum and watch it swing. The pendulum swings in a straight line, back and forth as the force of gravity acts upon it. We observe that the swing appears to rotate, but we insist that it swings in a straight line, so the Earth must be turning beneath it. This is called a Foucault pendulum (pronounced "foo-co").

Pictures and stuff: https://en.wikipedia.org/wiki/Foucault_pendulum

Motion of the Earth around the sun depends even more heavily on assumptions. For a long time people thought the Earth was motionless and the planets followed complex circles. That led to a lot of inventions in geometry and clever mechanisms called "orrery". Several philosophers eventually persuaded everybody that better results were obtained by assuming that the Earth moved around the sun.

Pictures: https://en.wikipedia.org/wiki/Orrery

If you don't believe a concept then by definition it does not make sense. The fact is believing is seeing. Everybody who looks at the stars sees the same blobs of light. If you believe in gravity then you can see evidence of gravity at work. If you don't believe then you can not see the evidence and nobody can persuade you that it is there. This is significant because gravity is not the only theory about how the universe works. Another group says electric charge is the main factor in how the universe behaves. Both sides of this argument consider the other side to be deluded. And these are *scientists*.

So always be aware of your assumptions before you make any conclusions.

Answer 2

The rotation of the Earth on its axis causes day and night, while its orbit around the sun creates seasons. These movements are responsible for the changing position of the sun, moon, and stars in the sky.