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Hipparchus was the most important Greek astronomers of his time. He very accurately cataloged over 1,000 stars and invented the mathematical science of trigonometry. Ptolemy was a great admirer of Hipparchus's research and recorded some of it in his book the "Almagest". Hipparchus studied the finding of earlier astronomers and compared them with his own. He discovered the procession of the equinoxes and was able to calculate the tropical year within 6.5 minutes of modern measurements. The tropical year is the length of the year measured by the Sun. Hipparchus devised a method of locating geographic positions by means of latitudes and longitudes which is still in use today.



Hipparchus was the most important Greek astronomers of his time. He very accurately cataloged over 1,000 stars and invented the mathematical science of trigonometry. Ptolemy was a great admirer of Hipparchus's research and recorded some of it in his book the "Almagest". Hipparchus studied the finding of earlier astronomers and compared them with his own. He discovered the procession of the equinoxes and was able to calculate the tropical year within 6.5 minutes of modern measurements. The tropical year is the length of the year measured by the Sun. Hipparchus devised a method of locating geographic positions by means of latitudes and longitudes which is still in use today.
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Aristarchus, Sun at center of Universe
Aristarchus of Samosis the first person we know of who suggested that the earth might go around the sun and not the other way around. He figured this out by looking at the shadow of the earth on the moon during an eclipse of the moon (now that Thales... 






Antikythera Mechanism, Astronomical Clock
The Antikythera mechanism is an ancient mechanical computer designed to calculate astronomical positions. It was recovered in 1900–1901 from the Antikythera wreck. Its significance and complexity were not understood until decades later. Its time of c... 






Ptolemy, Astronomer / Mathematician
Claudius Ptolemy was a GrecoEgyptian writer of Alexandria, known as a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in the city of Alexandria in the Roman province of Egypt, wrote in... 






John Harrison, Solved Longitude  1773
John Harrison was a selfeducated English carpenter and clockmaker. He invented the marine chronometer, a longsought after device for solving the problem of establishing the EastWest position or longitude of a ship at sea, thus revolutionising and... 



















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