Katie+Fear+and+Victoria+Loechel


 * Katie Fear and Victoria Loechel's Page

7. __Eratothenes__ Eratothenes was born in Cyrene (Modern day Libya). He was a mathematician, poet, athlete, geographer, and astronomer. He was best known for finding the circumference of the Earth, creating latitude and longitude, estimating the distance from the Earth to the Sun. When he was 30, Pharaoh Ptolemy III asked him to come to Alexandria, Egypt, to tutor the king's son, Philopator; also to be a librarian at the Library of Alexandria. **Eratosthenes knew that on the summer solstice at noon in Swenet on the Tropic of Cancer, the sun would appear directly overhead. He also knew, that in his hometown of Alexandria, the angle of elevation of the Sun would be 1/50 of a full circle, south of the zenith at the same time. Assuming that Alexandria was north of Syene he concluded that the distance from Alexandria to Syene must be 1/50 of the circumference of the Earth. His estimated distance between the cities was 5000 stadia. He rounded the result to a final value of 700 stadia per degree, which implies a circumference of 252,000 stadia.

8. __Ptolemy__- was a Mathematician, Astronomer, Geographer, and Astrologer. He lived in Roman Egypt. He envisioned a geocentric system involving epicycles to explain sky movements. Epicycle is the orbit of a planet in the Ptolemaic model, the center of which revolves around the earth in another circle. Ptolemy was able to use circle to make a model that fit the planets' motions. It took more than one circle for each planet. Ptolemy, claimed to have found his geometrical models from selected astronomical observations by his predecessors spanning about 800 years, though astronomers have for centuries suspected that his models' parameters were adopted from observations. Ptolemy presented his astronomical models in convenient tables, which could be used to compute the future and/or past position of the planets. The //Almagest// also contains a star catalog, which is an appropriated version of a catalogue created by Hipparchus.

9. __Nicolas Copernicus__- was a Polish astronomer, the first astronomer to come up with the idea of a heliocentric universe, which means that unlike the geocentric universe the heliocentric means that the sun is the center of the universe. Copernicus wrote the book, //__De revolutionibus orbium colestium__//, which was published in 1539. He did all of his work in the 1400-1500's. Some interesting facts about him are: after he died the street that he was born on was named after him, his name was published in about 4 different ways varying on the country that it was published in, and his surname means "he who works with copper."