Chapter 1 The Copernican Revolution

The planets’ motions Wanderers among the stars Retrograde motion

Figure 1.1 Planetary Motions

Geocentric models of the Universe Earth at center of solar system Aristotle ( B.C.) Ptolemy ( A.D. approximately)

Figure Geocentric Model

Figure Ptolemy’s Model

History of modern astronomy and heliocentric models Sun at center of solar system Copernicus ( ) Brahe ( ) Galileo ( ) Kepler ( )

Figure Nicholas Copernicus

Figure Retrograde Motion

Figure Galileo Galilei

Figure 1.7 Galilean Moons

Figure 1.8a - Venus Phases Sun-centered model

Figure 1.8b - Venus Phases Ptolemy’s model

Figure Johannes Kepler

Figure 1.10 Tycho Brahe

Kepler’s laws of planetary motion 1st law - elliptical orbits 2nd law - equal areas in equal times 3rd law - P 2 proportional to a 3

Figure Ellipse

Figure 1.12 Orbital Properties

Figure Kepler’s Second Law

Figure Astronomical Unit

Figure Isaac Newton

Newton’s Three Laws of Motion 1. Motion remains constant unless force acts 2. Force = mass X acceleration 3. Forces occur in pairs on two bodies

Figure 1.16 Newton’s First Law

Newton’s Law of Gravity The force of gravity is Stronger with larger masses Stronger with smaller distances

Figure Gravity

Figure 1.18 Gravitational Force

Figure 1.19 Sun’s Gravity

Figure Center of Mass

Figure 1.21 Orbits