How do you distinguish between astronomy, cosmology, and astrophysics? What are their links with physics?
Cosmology and astrophysics are specialisations of astronomy.
Astronomy is about the observation of bodies in the sky. These include planets, moons, comets, stars, galaxies, nebulae and other objects. It involves determining the position, distance, motions and brightness of objects.
Cosmology is about understanding big picture of the Universe. It asks questions about how the Universe began, how it is evolving and what will happen to it in the future.
Astrophysics is about understanding how stars, galaxies and other objects work. Astrophysics is concerned with the physics and chemistry of these objects. It is used to determine the chemical composition of gas clouds and the atmospheres of planets and the fusion reactions taking place in stars.
Astronomy is a very diverse subject. It has many specialisations of which cosmology and astrophysics are examples.