Historical Models of our Solar System and Keplers

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Historical Models of our Solar System and Kepler’s Laws of Planetary Motion

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

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

Heliocentric Model • Sun is center of our

Galileo • Supporter of Copernicus’s Heliocentric theory • House arrest • Observed moons orbiting

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

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 1 st Law - Law of Ellipses Each planet

Kepler’s Laws of Planetary Motion 1 st 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

Eccentricity • Degree of elongation • Shapes or shape of planet’s orbit • Ratio

Eccentricity • Degree of elongation • Shapes or shape of planet’s orbit • Ratio between the foci and length of major axis • Circular =0 • Very elongated =1

2 nd Law – Law of Equal Areas • An imaginary line between the

2 nd 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.

3 rd Law – Law of Periods • Mathematical relationship P 2 = a

3 rd Law – Law of Periods • Mathematical relationship P 2 = a 3 • 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

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.

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.