Aryabhata is widely regarded as the father of Indian astronomy. He lived in the 5th century CE and made significant contributions to the field, including the development of the Aryabhata system of astronomy.

Aryabhata proposed the heliocentric model of the solar system, which places the Sun at the center of the system with the Earth and other planets revolving around it. This model was later developed by European astronomers such as Nicolaus Copernicus.

The armillary sphere is an astronomical instrument used to demonstrate the apparent motions of celestial bodies. It consists of a series of concentric rings representing the celestial sphere, the ecliptic, and other important astronomical circles.

Brahmagupta wrote the treatise 'Surya Siddhanta', which is considered one of the most important works in ancient Indian astronomy. It contains detailed astronomical calculations and tables, including the positions of celestial bodies, the calculation of eclipses, and the prediction of planetary motions.

The Ujjain Observatory was an ancient Indian observatory located in the city of Ujjain. It was one of the most important centers of astronomical research in ancient India and was used to make observations of celestial bodies and calculate astronomical data.

Varahamihira developed the concept of 'grahas' or planets, which are celestial bodies that move relative to the fixed stars. He identified nine grahas, including the Sun, the Moon, and the five visible planets.

The Rigveda is the oldest of the four Vedas, the sacred texts of Hinduism. It contains information about the constellations, planetary positions, and eclipses, indicating that astronomy was already being studied in ancient India during the Vedic period.

Brahmagupta developed the concept of 'karanas', which are astronomical techniques used for calculating the positions of celestial bodies. These techniques were used to create astronomical tables and calendars.

The Brihat Samhita is an ancient Indian astronomical text written by Varahamihira. It contains detailed descriptions of astronomical instruments and their uses, as well as information about astrology, meteorology, and other related topics.

Varahamihira developed the concept of 'yugas', or cosmic cycles, and proposed the idea of a repeating cycle of creation and destruction. He identified four yugas: Satya Yuga, Treta Yuga, Dwapara Yuga, and Kali Yuga.

The Surya Siddhanta is an ancient Indian astronomical text that contains detailed information about eclipses, planetary motions, and the calculation of astronomical data. It is considered one of the most important works in ancient Indian astronomy.

Varahamihira developed the concept of 'ashtakavarga', which is a system of eight divisions of the zodiac used for astrological predictions. This system is still used in Indian astrology today.

The Panchasiddhantika is an ancient Indian astronomical text that contains information about the construction and use of astronomical instruments, as well as tables of astronomical data. It is a compilation of five different astronomical systems.

Varahamihira developed the concept of 'graha-yuddha', or planetary warfare, which is the study of the interactions between planets and their effects on human affairs. This concept is still used in Indian astrology today.

Lilavati is an ancient Indian astronomical text written by Bhaskaracharya. It contains information about the construction and use of sundials and other timekeeping instruments, as well as other mathematical and astronomical topics.