Ancient Astronomers

Eratosthenes

240 BCE

Eratosthenes is most famous for making the first accurate measurement of the circumference of the Earth. This is important because it contributes to the field of geodesy which is the study of the shape and size of the Earth. He made this discovery around 240 BC

Ptolemy

150 BCE

He made a model of the solar system and this was important because this model helped us understand the structure of the solar system because it was so accurate. He made this discovery around 150 AD

Copernicus

1514

Copernicus developed the first sun centered model of the solar system. This is important because Copernicus corrected Eratosthenes' model where the Earth is the center because his model was incorrect and Copernicus' sun centered model is correct

Tycho Brahe

1562

Tycho recorded planetary positions ten times more accurately than the best previous work. He built vast instruments and used multiple clocks and time keepers. Brahe's discovery of planetary position is important because later it helped with Kepler's theories.

Johannes Kepler

1609

Using the careful observations of Tycho Brahe, Kepler devised three laws that govern planetary motion. His major contribution was the idea that planets and other satellites move in elliptical orbits, not perfect circles. Kepler's three laws were important because they were a big jump in understanding planetary motion.

Isaac Newton

1666

Isaac Newton discovered the basic laws of motion. His discovery of these laws is important because they form the basic principles of modern physics.

Albert Einstein

1905

Einstein discovered the Theory of Relativity which is important because this theory changed the way scientists look at the world and set the foundation for many modern inventions, including the nuclear bomb and nuclear energy. One equation from the theory is E=mc2.