Historical Models of our Solar System Miss Scillieri 6 th Grade

Geocentric Model Geocentric-Earth is center of our Solar System Unexplained on how planets appear to move backwards Ptolemy- Was an ancient Greek scientist who theorized planets and Sun move in small circles around Earth

Heliocentric Model Sun is center of our Solar System Nicholas Copernicus was a Polish astronomer, who first suggest heliocentric theory and vaguely mapped out the planets orbiting the sun in a circular orbit.

Galileo Supporter of Copernicus’s Heliocentric theory Observed moons orbiting Jupiter and theorized objects can revolve around other planets not just Earth Telescope was crude, he saw only 4 of 63 moons of Jupiter Galileo proved heliocentric theory by observing the moons of Jupiter. He was placed under house arrest. If he did not “denounce” or say his science was a lie he would face death.

Not a perfect circle…an ellipse Tycho Brahe- studied Solar System and made very accurate recordings of his observations- scientific method! Tycho’s assistant, Kepler, used information for the details of orbits, this complex math based on observations would not be published to after both men had died. Using Brache’s data, scientist Kepler found out that each planet moves around the sun or is “wheels on wheels” Simply put each planet orbits the Sun in an ELLIPTICAL orbit of a certain size.

Sketch a geocentric model using the Earth and Sun: Sketch a heliocentric model using the Earth and Sun: Match the scientist to his contribution __ Used a telescope to discovery moons of Jupiter proving HELIOCENTRIC theory ___ Supported the GEOCENTRIC theory and thought planets orbited in CIRLCES ___ Used complex math equations to prove planets move in ellipses ___ First person to theorize heliocentric theory A.Copernicus B.Galileo C.Kepler D.Ptomely

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 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 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 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 this publication, considered to be the greatest piece of scientific literature ever written. Contains Newton’s laws of motion including universal gravitation.

Einstein ( ) 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 Bibliography