Aryabhata proposed that the Earth is spherical in his treatise, the Aryabhatiya.

Aryabhata proposed the theory of the Sun's motion around the Earth in his treatise, the Aryabhatiya.

Aryabhata used the epicycle called 'Mandala' to explain the Sun's motion.

Aryabhata proposed that the Sun makes one revolution in a day.

Bhaskaracharya discussed the Sun's motion in his treatise, the Siddhanta Shiromani.

Bhaskaracharya proposed that the Sun's motion is due to its own motion.

Bhaskaracharya proposed the geocentric model to explain the Sun's motion.

In the geocentric model, the Sun is positioned at the center of the solar system.

Aryabhata proposed the theory of the Earth's rotation in his treatise, the Aryabhatiya.

Aryabhata proposed that the Earth completes one rotation in 24 hours.

Indian astronomers used the gnomon, a simple instrument, to observe the Sun.

Indian astronomers used the gnomon to measure the Sun's position in the sky.

Aryabhata developed a method to calculate the Sun's distance from the Earth in his treatise, the Aryabhatiya.

Aryabhata calculated the Sun's distance from the Earth to be approximately 93 million miles.

Bhaskaracharya proposed the theory of the Sun's elliptical orbit in his treatise, the Siddhanta Shiromani.