Aryabhata
He proposed a heliocentric model with Earth rotating on its axis and accurately calculated the length of the sidereal year.
Most quoted
"Just as a person in a boat going forward sees the stationary objects on the shore as moving backward, just so are the stars, though stationary, seen by the people on the earth as moving westward."
— from Aryabhatiya, Gola (Sphere) Chapter, Verse 9
"Just as a man in a boat going forward sees the stationary objects on the shore as moving backward, just so are the stars seen as moving backward by the people on the Earth moving forward."
— from Aryabhatiya (rephrasing of a core concept)
"Just as a person in a boat moving forward sees the stationary objects on the bank as moving backward, in the same way, a person on the Earth sees the stationary stars as moving backward."
— from Aryabhatiya, Gola (Sphere) 9, 499
All quotes by Aryabhata (366)
The sidereal period of the Earth is 365 days, 6 hours, 12 minutes, and 30 seconds.
The sine of an angle can be calculated using a table of sines.
The concept of zero is essential for performing calculations.
The Earth is not stationary, but rotates on its axis.
The apparent motion of the stars is due to the rotation of the Earth.
The Earth is a sphere, not flat.
Eclipses are not caused by Rahu and Ketu, but by the shadows of celestial bodies.
The planets have their own orbits around the Sun.
The Earth is the center of its own motion, not the center of the universe.
The length of a year is not exactly 365 days, but slightly more.
Mathematics is the foundation of astronomy.
The use of decimal place value system is crucial for accurate calculations.
The concept of negative numbers is useful in certain mathematical operations.
The Earth is not supported by anything, but floats in space.
The stars are fixed, and their apparent motion is due to the Earth's rotation.
The true positions of the planets can be calculated using mathematical models.
The precession of the equinoxes is a real phenomenon.
The Earth's axis is tilted, causing the seasons.
The circumference of a circle is proportional to its diameter.
The area of a triangle is half the product of its base and height.