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1528 BCE
Claudius Ptolemy
Published his "Almagest". This work was important because it was the dominant model of the universe for over a thousand years and provided a framework for understanding the motions of the planets. (In the 2nd century) -
240 BCE
Eratosthenes
Measured the circumference of the Earth. This discovery was important because it was the first time anyone had accurately measured the size of the Earth. -
May 24, 1543
Nicolaus Copernicus
Published "De Revolutionibus Orbium Coelestium". This work was important because it challenged the geocentric model of the universe that had been accepted for centuries and proposed the heliocentric model. -
Nov 11, 1570
Tycho Brahe
Discovered a new star in the constellation Cassiopeia. The discovery was important because it contradicted the Aristotelian Idea that the universe was perfect and unchanging. -
Johannes Kepler
Published his Astronomia Nova. This work was important because it provided a mathematical basis for Copernicus's heliocentric model of the universe. -
Sir Isaac Newton
Published his "Philosophiae Naturalis Principia Mathematica". This work was important because it explained how objects move in the universe and provided a foundation for modern physics. -
Albert Einstein
Published his theory of general relativity. This theory was important because it revolutionized the way we think about gravity and space-time.