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Eratosthenes becomes the first person to measure the circumference of the Earth. His calculations, which were fairly accurate, proved importance by opposing the widely accepted view at the time that the Earth was flat. His other discoveries and inventions include the creation of a method for finding prime numbers, a map of the known world during his time period, a system of latitude and longitude, and a calendar with leap years, among others. -
Claudius Ptolemy proposes his geocentric theory, in which the Earth is the center of the universe. This theory became widely accepted and remained so for centuries until later rejected and proven incorrect. He also became famous for his work in geography, including the use of latitude and longitude lines to identify locations on Earth. -
Nicolaus Copernicus proposes his heliocentric theory, in which the Earth and other heavenly bodies revolve around the Sun. This theory was not only deemed important at the time due to its rejection of the accepted geocentric theory, but remains relevant today as being an accurate description of the universe. His work also largely inspired later astronomers, including Galileo and Kepler. -
Tycho Brahe dedicated his life to accurately observing the heavenly skies during the time period before the invention of the telescope. His observations later influenced and enabled Kepler to disprove Ptolemy's geocentric theory. He also built the world's first observatory, logged over 1,000 stars, and discovered a supernova in the Cassiopeia constellation. -
Galileo Galilei becomes the first person to observe the sky with an improved telescope and discovers moons orbiting Jupiter, craters on the Moon, and the Milky Way galaxy. His work was greatly inspired by Copernicus and heliocentrism, and was therefore denied and rejected by the Catholic Church and its teachings of geocentrism. However, his work would later be acknowledged as scientific truth and continues to influence the modern field of astronomy. -
By having access to Brahe's observations, specifically his accurate observations of Mars, Kepler was able to discover that planets followed elliptical, rather than circular, orbits. This would become one of Kepler's three laws of planetary motion, all of which enforced heliocentrism and explained the ways in which planetary bodies move, and their speeds and distances of their planetary orbits. Kepler's laws gained even more importance after influencing and being proven by the work of Newton. -
Sir Isaac Newton, influenced greatly by Kepler's laws of planetary motion, develops his theory of universal gravitation. His work explained the reason why planets stay in their orbits in our solar system, why things fall from the sky, and solved many other mysteries that people had been questioning for centuries. His work also helped to explain and prove Kepler's laws. He also developed three laws of motion, which explain the motion of forces between objects, and invented calculus. -
Einstein publishes the second part to his theory of relativity, which proposes a completely new way of looking at the universe, much of which continues to be pondered by modern scientists. For example, Einstein predicted that space and time are linked together by gravity, and that the speed of light in a vacuum is constant. He also invented physics, and suggested that the laws of physics remain unchanged throughout the universe. His work continues to make him one of the most famous scientists.