Aryabhata is widely regarded as the father of Indian astronomy due to his groundbreaking work in the 5th century CE. He made significant contributions to various fields of astronomy, including trigonometry, algebra, and planetary motion.

Aryabhata was the first Indian astronomer to propose the heliocentric model of the solar system, where the Earth and other planets revolve around the Sun. This revolutionary idea challenged the prevailing geocentric model and laid the foundation for modern astronomy.

Varahamihira, a renowned Indian astronomer and astrologer, discovered the variable star Algol in the 6th century CE. He observed the periodic changes in the brightness of Algol and documented its variability.

Brahmagupta, a prominent Indian mathematician and astronomer, developed the concept of the 'zero' and introduced it to the world in the 7th century CE. This groundbreaking idea revolutionized mathematics and astronomy, enabling the development of new mathematical techniques and astronomical calculations.

Aryabhata authored the influential astronomical treatise 'Surya Siddhanta' in the 5th century CE. This comprehensive work covered various aspects of astronomy, including planetary motion, eclipses, and the calculation of time. It had a profound impact on the development of astronomy in India and beyond.

Aryabhata calculated the Earth's circumference with remarkable accuracy in the 5th century CE. Using geometric principles, he estimated the Earth's circumference to be approximately 40,000 kilometers, which is close to the modern value.

Varahamihira developed the 'Panchang', a traditional Indian calendar that is still widely used today. The Panchang provides information about various astronomical events, such as the positions of planets, eclipses, and auspicious dates.

Aryabhata was the first Indian astronomer to propose that comets are celestial bodies rather than atmospheric phenomena. He suggested that comets move in elliptical orbits around the Sun, challenging the prevailing belief that they were merely atmospheric disturbances.

Brahmagupta discovered the 'Brahmagupta's identity', a fundamental formula in trigonometry that relates the sine and cosine functions. This identity is widely used in various branches of mathematics and physics.

Bhaskara II developed the 'Bhaskara's method' for solving quadratic equations. This method involves completing the square to transform the quadratic equation into a perfect square, which can then be easily solved.

Bhaskara II wrote the astronomical treatise 'Lilavati', which contains a wealth of information on arithmetic, geometry, and astronomy. This work is considered a masterpiece of Indian mathematical and astronomical literature.

Aryabhata was the first Indian astronomer to propose that the Earth rotates on its axis. This revolutionary idea challenged the prevailing belief that the Earth was stationary and the Sun moved around it.

Aryabhata developed the 'Aryabhata's equation', which relates the sine and cosine functions. This equation is widely used in trigonometry and is named after Aryabhata in recognition of his contributions to the field.

Bhaskara II wrote the astronomical treatise 'Siddhānta Shiromani', which covers various topics including astronomy, mathematics, and astrology. This work is considered one of the most important astronomical texts in Indian history.

Bhaskara II discovered the 'Bhaskara's theorem', which relates the area of a cyclic quadrilateral to the lengths of its sides. This theorem is widely used in geometry and is named after Bhaskara II in recognition of his contributions to the field.