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The Most Famous Astronomers of All TimeFor as long as humanity has gazed up at the stars, there have been astronomers studying the heavens in order to explain those bright lights in the sky.
See some of the most famous astronomers and physicists throughout history, from humanity's earliest observations of celestial events to today's investigations of deep sky objects that hold the secrets of the universe.
FIRST STOP: Ptolemy
Claudius PtolemySlide 2 of 23
Claudius PtolemyClaudius Ptolemy (AD 90-168) lived in Egypt but possessed Greek ancestry. As a mathematician, geographer and astronomer, he authored several scientific texts which had considerable impact on Western intellectual thought.
In the 2nd century, Ptolemy published the Almagest, a comprehensive treatise on the movements of the stars and planets. It expanded Hipparchus’ geometric model of celestial motions, utilizing epicycles and eccentric circles in a geocentric theory which placed the Earth at the center of the solar sys tem. This Ptolemaic system presented tables of information allowing convenient predictions of planetary locations. Ptolemy also catalogued 48 constellations, the names of which are still in use at present.
Ptolemy’s writings stood as authoritative for more than twelve hundred years. However, his model, which was incorrect, later fell out of use as the heliocentric view of the solar system came into being.
Few details about Ptolemy’s life survived to the present day.
NEXT: CopernicusSlide 3 of 23
Nicolaus CopernicusSlide 4 of 23
Nicolaus CopernicusNicolaus Copernicus (1473-1543) shattered the long-held notion that the Earth was the center of the solar system, proposing a heliocentric (sun-centered) model instead.
Copernicus, of Poland, felt the Ptolemaic view of the planets traveling in circular orbits around the Earth was over-complicated with many smaller circles, epicycles, needed to explain the intermittent retrograde motion of the planets (in which they appear to move in the opposite direction of the the stars). Copernicus published his book, De Revolutionibus Orbium Coelestium ("On the Revolutions of the Heavenly Spheres") when he was 70 and lay dying.
His ideas took almost a hundred years to gain credence, but Galileo's 1632 assertions that the Earth orbited the sun built upon the Polish astronomer's work, cementing the Copernican revolution. [Read more about Copernicus.]
NEXT: KeplerSlide 5 of 23
Johannes KeplerSlide 6 of 23
Johannes KeplerJohannes Kepler (1571–1630) defended and modified the Copernican view of the solar system with a radical reformation that established him as one of the great lights of the Scientific Revolution of the 16th-17th centuries.
Kepler deduced that the planets do not travel in perfect circles around the Sun, as Copernicus had thought, but rather possess elliptical orbits, with the sun at one of the foci. This insight formed his first planetary law, which he published in 1609 with the second law which stated that planets do not travel at the same rate throughout their orbits.
Kepler's third law, published a decade later, posited that the relationship between the length of two planets' orbits is related to their distances from the sun. Though he made other contributions to mathematics and optics, Kepler's three laws made him a giant of astronomy. [Read more about Kepler.]
NEXT: GalileoSlide 7 of 23
Galileo GalileiSlide 8 of 23