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Historical Models of our Solar System and Kepler’s Laws of Planetary Motion. Geocentric Model. Earth is center of our Solar System Aristotle- Over 2000 years ago, Unexplained on how planets appear to move backwards Ptolemy- Planets move in small circles or epicycles.
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Historical Models of our Solar Systemand Kepler’s Laws of Planetary Motion
Geocentric Model • Earth is center of our Solar System • Aristotle- Over 2000 years ago, • Unexplained on how planets appear to move backwards • Ptolemy- Planets move in small circles or epicycles
Heliocentric Model • Sun is center of our Solar System • Copernicus- Over 450 years ago (1543 ad) • First to suggest heliocentric theory and vaguely mapped out the planets orbiting the sun in a circular orbit.
Galileo • Supporter of Copernicus’s Heliocentric theory • House arrest • Observed moons orbiting Jupiter and theorized objects can revolve around other planets not just Earth
Solar System precisely measured • Tycho Brahe- studied Solar System and made very accurate recordings of his observations • Tycho’s assistant, Kepler, used information for the details of orbits
Kepler’s Laws of Planetary Motion 1st Law - Law of Ellipses Each planet orbits the sun in a path called an ellipse or elongated circle Ellipse is a closed curve whose path is determined by 2 points or foci within the ellipse Focus 1 is the Sun and Focus 2 is an imaginary point Semi-major axis = average distance from sun (AU); ½ major axis
Degree of elongation or shape of planet’s orbit Ratio between the foci and length of major axis Circular =0 Very elongated =1 Eccentricity
2nd Law – Law of Equal Areas • An imaginary line between the Sun and a planet sweeps out equal areas in equal times as the planet travels around the ellipse.
3rd Law – Law of Periods • Mathematical relationship P2 = a3 • a= semi-major axis (planets average distance from Sun measured in AU’s) • p= planet’s orbital period (time)
Newton • Used Kepler’s Laws of planetary motion and published Principia for short. In this publication, considered to be the greatest piece of scientific literature ever written. • Contains Newton’s laws of motion including universal gravitation.
Einstein (1879-1955) • Changed Newton’s gravitational theory based on findings of Mercury’s orbit. • Developed Theory of Relativity. It completely changed the way we study gravity and even changed our understanding of the universe.
Kepler’s Laws Simulations • Click http://www.physics.sjsu.edu/tomley/kepler.html Bibliography • http://www.astro.umass.edu/~myun/teaching/a100/images/geocentric.jpg • http://www.physics.hku.hk/~nature/CD/regular_e/lectures/images/chap04/heliocentric.jpg • http://www.3villagecsd.k12.ny.us/wmhs/Departments/Math/OBrien/galileo5.jpg • http://galileo.rice.edu/sci/brahe.html • http://www.asu.cas.cz/~had/tycho.jpg • http://cseligman.com/text/history/ellipse2.jpg • http://www.windows.ucar.edu/the_universe/uts/kepler3_small.gif • http://library.thinkquest.org/27585/frameset_intro.html • http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/imgrel/merc.gif • http://zebu.uoregon.edu/~soper/Orbits/eccentricity.gif • http://www.physics.hku.hk/~nature/CD/regular_e/lectures/images/chap04/geocentric.jpg • http://outreach.atnf.csiro.au/education/senior/cosmicengine/images/cosmoimg/keplerellipse.gif