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240 BCE
Eratosthenes (276 BCE -195 BCE)
Calculated the circumference of the Earth without leaving Egypt. His measurement was off by only 211 miles from the true measurement. -
150
Claudius Ptolemy (90-168 AD)
His first major astronomical work, the Almagest, contains reports of astronomical observations that he had made over the preceding quarter of a century. -
1532
Nicolaus Copernicus (1473-1543)
He completed his manuscript telling how he came up with the heliocentric system, this put the Sun (helio) at the center of the solar system. -
1573
Tycho Brahe (1546-1601)
He published a small book, De nova stella, thereby coining the term nova for a "new" star. This is classified as a supernova and we know that it is 7500 light-years from Earth. -
Johannes Kepler (1571-1630)
He founded the three laws of planetary motion. Based on his information, he knew the moon's gravity controls the tides. -
Sir Isaac Newton (1642-1727)
Published his work sharing his three universal laws of motion. -
Albert Einstein (1879-1955)
He applied the general theory of relativity to the structure of the universe as a whole.