ANCIENT CIVILISATION AND ASTRONOMY ANCIENT GREEK ASTRONOMY The earliest days of astronomy: 1. It was very dark at night since there were no artificial lighting. 2. Certain behaviours and patterns became obvious; • The sky is vast and very impressive as it appeared to be a huge sphere turning on an axis. There was a north and south pole and an equator. Stars rose in the east and set in the west as if they were attached to this vast sphere. Hence the concept of the celestial sphere. The first Greek Astronomers • Greek Astronomers were at their peak between 700 BC- 300 AD • At first, the ancient Greek were very superstitious as they believed that the world was very supernatural but later turned their views to natural theories. • The first Greek Astronomers includes; i. Thales the Astronomer ii. Anaximanda iii. Pythagoras iv. Plato v. Eudoxus of Cnidus vi. Autolycus vii. Aristarchus of Samos viii. Eratosthenes ix. Hipparchus x. Ptolemy THALES THE ASTRONOMER • Thales was one of the seven sages of Greece who was best in mathematics, astronomy and philosophy • Thales described a simple model of a small flat Earth surrounded by a sheet of water, with a single vast sphere • He predicted the solar eclipse ANAXIMANDA • Anaximanda was the first speculative astronomer who follows after Thales • He made many achievements on the idea of the sun being 27 times larger than earth PYTHAGORAS • Pythagoras was the first to suggest that there was a harmony of the spheres, and that the sun, planets, moon and stars’ movements could be described by mathematics • He’s probably one of the first people to believe that the earth is round • His followers were called Pythagoreans PLATO • Plato believed in the idea that the sun, stars and moon were fixed onto concentric spheres that are rotating inside one another • He proposed that the stars formed the outermost sphere, then followed by planets, the sun, the moon and lastly the earth at the centre of it all EUDOXUS OF CNIDUS • Eudoxus Of Cnidus was a great astronomer and mathematician though his work has been lost • He advanced well in identification of constellation • He believed that earth rest at the centre and 27 concentric spheres rotate around this center. AUTOLYCUS • Autolycus believed in Eudoxus’s work • He wrote that "any star which rises and sets always rises and sets at the same point in the horizon." ARISTARCHUS OF SAMOS • Aristarchus Of Samos is the first ancient Greek astronomer and a mathematician to represent the first heliocentric model • even though he was right people at first laughed at his theory • He tried to estimate the size and distances of the heavenly bodies ERATOSTHENES • Eratosthenes made more advancements on ARISTARCHUS OF Samos’s theories as he calculated the size of the earth. • He discovered that the size of the earth was 25 000 miles around but he was 1 000 miles of HIPPARCHUS • Hipparchus was famous for using science to form his theories and was the greatest ancient astronomical observer • He is the first whose quantitative and accurate models for the motion of the sun and moon to survive’ • He calculated the distance of heavenly bodies using trigonometry CLAUDIUS PTOLEMY • Ptolemy presented a useful tool for astronomical calculations in his Handy Tables • He believed that earth was at the centre of the universe according to his observation • Most of his work was based on Hipparchus’s work • After Ptolemy there were no more ancient Greek astronomers therefore Greek astronomy ended. • though the Greek astronomy ended, their ancient theories on astronomy paved a way for modern physics on astronomy and those theories are now been proven to be correct, some are discarded and refined as time goes on. REFERENCE • For more information on Greek astronomy; i. Go to Biust library and search for documentary in Greek astronomy ii. Thurston, H., Early Astronomy. Springer iii. Pedersen, Olaf (1993). Early Physics and Astronomy: A Historical Introduction (2nd ed.) Thank you for you undivided attention