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240 BCE
Eratoshenes
In 240 B.C Eratosthenes Measures the Earth. By around 500 B.C most ancient Greeks believed that the Earth was round and not flat. But they had no idea how big the planet is until about 240 B.C when Eratoshenes devised a clever method of estimating its circumference. -
126 BCE
Ptolemy
Ptolemy was an astronomer and mathematician. He believed that the Earth was the center of the Universe. The word for earth in Greek is geo, so we call this idea a "geocentric" theory.t gives in detail the mathematical theory of the motions of the Sun, Moon, and planets. Ptolemy made his most original contribution by presenting details for the motions of each of the planets. His theories were not superseded until a century after Copernicus presented his heliocentric theory in 1543. -
1514
Nicholas Copernicus
Copernicus developed his own celestial model of a heliocentric planetary system. Around 1514, he shared his findings in the Commentariolus. His second book on the topic, De revolutionibus orbium coelestium, was banned by the Roman Catholic Church decades after his May 24, 1543 death in Frombork. -
1578
Tycho Brache
Danish astronomer whose work in developing astronomical instruments and in measuring and fixing the positions of stars paved the way for future discoveries. Tycho Brahe was a Danish nobleman and astronomer, and he was one of the individuals whose work helped overturn that belief in favor of a heliocentric model of the universe, with the sun at the center. -
Sir Isaac Newton
Newton developed the three laws of motion which form the basic principles of modern physics. His discovery of calculus led the way to more powerful methods of solving mathematical problems. -
Johannes Kelper
German astronomer who discovered three major laws of planetary motion, conventionally designated as follows: the planets move in elliptical orbits with the Sun at one focus; the time necessary to traverse any arc of a planetary orbit is proportional to the area of the sector between the central body and that arc (the “area law”); and there is an exact relationship between the squares of the planets’ periodic times and the cubes of the radii of their orbits (the “harmonic law”).