Ptolemy

1
Ptolemy

• His real name is Claudius Ptolemaeus, but we know
  him as Ptolemy. Not much is known about his life.
  The name Claudius probably means he was a Roman
  citizen. The name Ptolemy means that he was
  Greek.
• It is believed that he lived from 90 to 170 CE.
  They know that he worked in the library of
  Alexandria, Egypt from 127 to 150 CE.
• He was an astronomer, mathematician and
  geographer.

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Discoveries

• He is famous for his work on astronomy and
  geography. His books were discovered in the
  Middle Ages, before the 12th century. They were
• Almagest the study of astronomy and geometry
• Tetrabiblios the study of astrology
• Geography which included maps of how they
  thought the world was like at the time

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Astronomy

• Ptolemy believed in the Greek geocentric view of
  the universe, that the Earth was at the center of
  the universe. He believed the planets and sun
  moved around the Earth in this order Mercury,
  Venus, Sun, Mars, Jupiter, Saturn.
• This system is called the Ptolemaic system. Its
  described in his book Almagest on astronomy.
• The book has information on the earth, sun, moon,
  stars and eclipses. It has a star catalog of 48
  constellations that we still use today.

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Mathematics

• He was also a mathematician. He discovered that
  any quadrilateral inside a circle with points A B
  C and D followed this equation, called Ptolemys
  theorem
• ACBD ABCD DABC

5
Geography

• Claudius Ptolemy was very important in the
  history of geography and making maps. His book
  Geography was the main one used until Christopher
  Columbus. It had 8 volumes.
• The ancient Greeks and Romans knew that the earth
  was round. In his 1st volume, he shows how to
  draw a spherical earth on a flat sheet of paper.
  Hes the first known person to do this.

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Geography

• He was the first person to put a grid system on
  the map and he was the one who invented latitude
  and longitude. He was also the first to put north
  at the top of the map.
• The problem was that his map had many errors
  because he had to go by the estimates of merchant
  travelers who didnt know how to measure
  longitude at the time.

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Geography

• Ptolemy made the mistake of assuming that the
  earth had a shorter circumference. Because of
  this, Christopher Columbus thought he could reach
  Asia by sailing west from Europe. He landed
  instead in the NewWorld.
• Ptolemy made many contributions to geography.
  Even the mistake he made led Columbus to discover
  America in 1492.

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Astrology

• Ptolemy was also an astrologer. His book
  Tetrabiblios was the most popular book on
  astrology at the time.
• He believed that the positions of the planets at
  the time of birth did influence a person, but not
  completely.

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Sources

• http//www.hps.cam.ac.uk/starry/ptolastrol.html
• http//geography.about.com/od/historyofgeography/a
  /ptolemy.htm
• http//simple.wikipedia.org/wiki/Ptolemy