Till 19th century astronomy mainly depends upon either observation with the naked eye or telescopic observation. After the discevory of the electromagnetic spectrum at the end of the 19th century our understanding of the universe increased enormously. Because of this development in the late 19th century it was found that Newton's law of gravitation could not explain certain phenomena and showed some discrepancies. Albert Einstein formulated his 'General theory of relativity' which was one of the most successful theories of 20th century in the field of graviation.
In the 20th century both astronomy and gravitation merged together and havee grown in manifold. The birth and death of stars were more clearly understood. Many Indian physicists made very important contributions to the field of astrophysics and gravitation.
Subramanian Chandrasekar formulated the theory of black holes and explained the life of stars. These studies brought him the Nobel prize in the year 1983. Another very notable Indian astrophysicist Meghnad Saha discovered the inonization formula which was useful in classifying stars. This formula is now known as " Saha ionization formula". In the field of gravitation Amal Kumar Raychaudhuri solved an equation now known as "Raychaudhuri equation" which was a very important contribution. Another notable Indian Astrophysicist Jayant V Narlikar made pioneering contribution in the field of astrophysics and has written interesting books on the astronomy and astriphysics. IUCAA ( Inter University Center for Astronomy and Astrophysics ) is one of the important research in astrophysics and gravitation are conducted. The institute was founded by Prof. J.V.Narlikar. Students are encouraged to read more about the recent developments in these fields.