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200 BCE
Eratosthenes (276–195 BC)
Eratosthenes was a Greek mathematician who used the sun to measure the size of the Earth. His calculations were only 211 miles off. This was a prominent progression because it helped to gradually eliminate the belief that the Earth was flat. -
150
Claudius Ptolemy (100-170)
Ptolemy wrote a history of previous observations, which helped to document an important part of how humanity has progressed. He also discovered that starlight is refracted through Earth's atmosphere. He was also the one to propose the geocentric model of the universe. Even though this model was incorrect, it altered how humans viewed the universe. -
1543
Copernicus (1473-1543)
Copernicus was the first to challenge the geocentric theory, proposing the geocentric theory. Before Galileo attempted to prove it with the telescope, Copernicus published various works justifying his claim. He was also the first to issue the theory that days and nights were caused by the Earth rotating on its axis. -
1580
Tycho Brahe (1546-1601)
Brahe observed the universe extremely accurately with only the human eye to prove he belief in an Earth-centric universe. While his theory was wrong, he did achieve his goal of measuring to one minute of arc, which was monumental to humanity's understanding of the universe before the invention of the telescope. -
Johannes Kepler (1571-1630)
Influenced by Brahe's work, Kepler went further to develop the three planetary laws that govern the motions of the planets. He was also the first to suggest that the planets did not move in perfect circles, but that their orbits were elliptical. All of his discoveries influence how astronomers research and view the universe today. -
Sir Isaac Newton (1642-1727)
Sir Isaac Newton formulated the basic laws of motion that govern how we look at physics and mechanics today. He also proposed the law of universal gravity as a mathematical law. These accomplishments are significant because they revolutionized how we viewed the universe in Newton's time and guide our research today. -
Albert Einstein (1879–1955)
Albert Einstein suggested that the laws of physics were the same throughout the universe, which gave the world a different perspective to view the universe from and analyze it in a more practical way. He also suggested that the speed of light is constant in a vacuum and that space and time were linked together by an entity known as "space-time".
