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 moon is much smaller than the Earth.
The planets have different colors and brightness.
The planets have their own periods of revolution around the sun.
The moon has no light of its own and reflects the sun's light.
The Earth is round like a ball and not flat.
The planets move in the sky because of their own motion and not because of the Earth's rotation.
The stars are distant suns and are not attached to the sky.
The sun is the center of the solar system and all planets revolve around it.
The moon's orbit is inclined to the Earth's orbit around the sun.
The planets have their own satellites, like the moon around the Earth.
The Earth's gravity holds everything on its surface.
The planets have different densities and compositions.
The sun's energy is the source of life on Earth.
The moon's gravity causes tides in the oceans.
The planets have their own atmospheres and weather patterns.
The stars are born, live, and die, like all things in the universe.
The universe is infinite and has no boundaries.
The Earth is just a small part of the vast universe.
The planets are constantly moving and never at rest.
The sun's light takes time to reach the Earth.