Question

why the pole star is stationary

Answer 1

The pole star looks stationary bc the appearance it's positioned close to the earth's axis line projected into space..

Answer 2

The pole star appears to be stationary when seen from the earth because it is located on the earth's vertical axis ( an imaginary line going through the north and south poles). Thus when the earth rotates, it rotates along with this axis, and so it never appears to move.