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Planets and Gravitational Attraction

Planets and Gravitational Attraction . A specific application of circular motion and its effects. Ancient Historical Giants. Greek philosophers Geocentric model Stars and the sun are giant spheres (the ideal shape) that rotate about the earth Earth does not move Ptolemy

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Planets and Gravitational Attraction

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  1. Planets and Gravitational Attraction A specific application of circular motion and its effects

  2. Ancient Historical Giants • Greek philosophers • Geocentric model • Stars and the sun are giant spheres (the ideal shape) that rotate about the earth • Earth does not move • Ptolemy • Lived from 87 to probably 170 AD • Egypt • Astronomer, mathematician and geographer

  3. Ptolemy’s Epicycles • Promoted idea of circular orbits • Epicycles • circles rolling upon larger circles • accounts for retrograde motion of Mars, Jupiter, and Saturn • used 80 or more epicycles to explain the motion of the five planets known when he was alive, as well as the motion of the sun and the moon. • Earth still the center of the universe

  4. Ptolemy http://pallisgaard.com/blog/category/software-development/

  5. Copernicus • Polish astronomer • 16th century • Renaissance man • heretic • Heliocentric model

  6. Copernicus • Heliocentric Model • Sun is center of universe • Sun does not move • Orbits of planets are circular http://www.cartage.org.lb/en/themes/sciences/Astronomy/Thestars/stellardistances/TheParallaxMethod/TheCopernicanModel/TheCopernicanModel.htm

  7. Galileo • Supportive of Copernicus • Sun at center of circular planetary orbits • Earth is just another planet • Earth must rotate on its own axis • Radius of earth approximately 6400 km • Must rotate 1680 km/hr (1000 mph) • Seemed impossible

  8. Galileo • Renaissance man, like Copernicus • Placed under house arrest even after recanting his support for Copernicus • Improved construction of telescope and used it to study moon and planets • Discovered moons of Jupiter http://www.famous-scientists.net/Galileo-Galilei.htm

  9. Tycho Brahe • Danish • Given an island, which he called Hven, by the Danish king • Spent 20 years making observations of the skies using only compass and sextant http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/brahe.html

  10. Johannes Kepler • Hired as an assistant by Tycho Brahe in 1600 • After Brahe died, he used Brahe’s extensive observations and measurements to derive first natural laws – the laws of planetary motion http://kepler.nasa.gov/johannes/

  11. Kepler • Kepler discovered that the orbit of Mars was an ellipse by carefully analyzing the copious data collected by Brahe • Developed his three laws of planetary motion, which are considered the first natural laws http://kepler.nasa.gov/johannes/#anchor778225

  12. Kepler’s Laws of Motion • Planets move in ellipses with the Sun at one focus. • The radius vector describes equal areas in equal times. • The squares of the periodic times are to each other as the cubes of the mean distances.

  13. Kepler • Also very interested in vision • Explained refraction which produced vision • Developed eyeglasses for both near and far-sightedness • Explained use of both eyes for depth perception • Explained various types of images made by the eye (real, virtual, upright, magnified, etc) • Explained how a telescope worked • Discovered and described total internal reflection

  14. Kepler • First coined the term “satellite” • First to explain that tides are caused by the moon ircamera.as.arizona.edu

  15. Isaac Newton • Using Kepler’s laws (not an apple), he developed the law of universal gravitation • More information can be found at: http://csep10.phys.utk.edu/astr161/lect/history/newtongrav.html

  16. http://knol.google.com/k/-/-/3p29xkwpauy98/jw5rzk/isaac-newton-inverse-square-law%20(1).jpghttp://knol.google.com/k/-/-/3p29xkwpauy98/jw5rzk/isaac-newton-inverse-square-law%20(1).jpg

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