The planets keep changing their position with respect to:

Stars

Planets are solid heavenly bodies that revolve around the Sun in closed elliptical paths. A planet is made of rock and metal and produces no light of its own. A planet shines because it reflects the light of the Sun. Since the planets are much nearer to the stars, they appear to be big and do not twinkle at night. The planets move around the Sun from West to East, so the relative positions of the planets keep changing day by day. They are very small compared to the sun and other stars.
Hence, the star appears to remain in a fixed position with respect to each other whereas the distance between the planets keeps changing constantly.