Presentation on theme: "The Ancient Roots of Science Ancient Greek Science."— Presentation transcript:
The Ancient Roots of Science Ancient Greek Science
Practical uses of astronomy To ancient people, the sky was both a clock and a calendar The orientation of the waxing crescent moon could be used to predict the rainy season in central Nigeria
The days of our week were originally named for the “wanderers”
Time can be told during the day using the Sun’s position
At night the Egyptians used a “star clock” It told where various stars could be seen at different times of night throughout the year.
Many cultures built structures to mark specific astronomical occasions Stonehenge
Stonehenge, built in stages over 1200 years, has alignments with many astronomical events. It was also used as a burial place for the elite This lane is now known to have been a naturally occurring stone path or lane
Callenish, Isle of Lewis, Scotland Newgrange, Ireland
Chichen Itza, Yucatán, Mexico El Caracol – alignments with the rising and setting of Venus El Castillo – same number of steps as days in a year Alignments with the equinoxes
Great Kiva in Chaco Canyon The Sun Dagger in Chaco Canyon
Chinese astronomers have been recording astronomical observations for at least 5000 years Machu Picchu includes alignments with summer and winter solstice sunrises Micronesia – stars for navigation
Do the structures built by ancient peoples for observing celestial events prove that they were doing science? A.No. There was no “science” before Isaac Newton. B.Yes. Observing the stars is scientific. C.No. Observation is only the first step in the scientific process. D.Yes. Since they were able to detect the solstices, they were doing science.
Four Greek contributions to the modern scientific method 1.They tried to understand nature without relying on supernatural explanations. 2.They used mathematics to state their ideas with precision. 3.They recognized that an explanation had to agree with observed facts. 4.They constructed MODELS of natural phenomena.
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Plato argued that, since the heavens are perfect, all heavenly bodies must move in circles (the only perfect shape) Therefore they must reside on crystalline spheres
Eratosthenes noticed that on the summer solstice, the Sun passed directly overhead in Syene. (A vertical stick cast no shadow.) On the same day in Alexandria, a vertical stick cast a 7º shadow. He knew the distance from Syene to Alexandria. He also knew that there are 360º in a full circle. He reasoned that the distance from Syene to Alexandria was 7/360 of the full circumference of the Earth. His calculated value was within 5% of the actual value.
Apollonius introduced a model wherein the planets moved on small circles that in turn moved around Earth in large circles. Hipparchus refined the model – and added complications to increase accuracy. After Ptolemy synthesized and published these earlier ideas, allowing the positions of planets to be forecast to an accuracy of a few degrees of arc. This was good enough that his model was used for the next 1500 years. Epicycle Deferent
Which of these was NOT a contribution of the ancient Greeks? A.Use of only natural explanations. B.Basing hypotheses on careful observations C.Thoroughly testing hypotheses D.Building models to explain natural phenomena
Astro-Cash Cab! Gabriela Gonzalez Angelica Raya Trejo Nathaniel Venters Stevon Cornish Lena Jaycox
1) Which of the following was NOT a practical use of astronomy for early people? A)Measuring elapsed time at night B)Predicting rainy and dry seasons C)Navigating at night D)These are all practical uses for early people
2) Who made the first reasonably accurate measurement of the size of the Earth? Eratosthenes Aristotle Ptolemy Democritus Apollonius
3) True or False? A model has to be physically true (i.e., real) in order to make good predictions.
4) What do we call the motion the planet displays at the indicated point?