Question

why does the luminance and the shape of polaris not remain stable​

Answer 1

$\huge\bold\red{Answer}$

Polaris, the North Star, appears stationary in the sky because it is positioned close to the line of Earth's axis projected into space. As such, it is the only bright star whose position relative to a rotating Earth does not change. All other stars appear to move opposite to the Earth's rotation beneath them.

Answer 2

Answer:

Polaris or pole star is the variable star such type of stars constantly contract or expand when the stars expand it emits less energy at this time it's brightness decreases on the other hand when a star contracts its surface temperature increase and star emits greater energy and appears brighter there for the luminants and the shape of polar is does not stable