Dear,

So basically, Cosmologists study the entire universe. They study the creation, evolution, and possible futures of the universe and its galaxies. These scientists have recently developed several theories important to the study of physics and astronomy, including string, dark-matter, and dark-energy theories. To become a cosmologist, you need a Ph.D. in physics, astronomy, or a related field is needed for jobs in research or academia or for independent research positions in industry. Many physics and astronomy Ph.D. holders who seek employment as full-time researchers begin their careers in a temporary postdoctoral research position, which typically lasts 2 to 3 years.

Hope this helps!