Aryabhata is considered the father of Indian astronomy because of his significant contributions to the field, including the development of the heliocentric model of the solar system and the calculation of the Earth's circumference.

Aryabhata proposed the theory of the Earth's rotation on its axis in his book, the Aryabhatiya.

Bhaskara II calculated the value of pi to four decimal places in his book, the Lilavati.

Brahmagupta developed the concept of the zero in his book, the Brahmasphuta Siddhanta.

Varahamihira wrote the Pancha Siddhantika, a treatise on five astronomical systems, in the 6th century CE.

The Jantar Mantar is an astronomical observatory built in the 16th century by Maharaja Sawai Jai Singh II in Jaipur, India.

Bhaskara II proposed the theory of the Earth's elliptical orbit around the Sun in his book, the Siddhanta Shiromani.

Varahamihira developed the concept of the zodiac in his book, the Brihat Samhita.

Aryabhata calculated the value of the Earth's radius in his book, the Aryabhatiya.

Brahmagupta developed the concept of the precession of the equinoxes in his book, the Brahmasphuta Siddhanta.

Varahamihira developed the concept of the nine planets in his book, the Brihat Samhita.

Varahamihira developed the concept of the constellations in his book, the Brihat Samhita.

Varahamihira developed the concept of the lunar nodes in his book, the Brihat Samhita.

Varahamihira developed the concept of the solar eclipse in his book, the Brihat Samhita.

Varahamihira developed the concept of the lunar eclipse in his book, the Brihat Samhita.