Chapter 1The Copernican Revolution

Chapter 1The Copernican Revolution

The planets’ motionsThe planets’ motions

• Wanderers among the stars

• Retrograde motion

Figure 1.1Planetary Motions

Geocentric models of the Universe

Geocentric models of the Universe

• Earth at center of solar system

• Aristotle (384 - 322 B.C.)

• Ptolemy (87 - 150 A.D. approximately)

Figure 1.2 - Geocentric Model

Figure 1.3 - Ptolemy’s Model

History of modern astronomy and heliocentric models

History of modern astronomy and heliocentric models

• Sun at center of solar system

• Copernicus (1473 - 1543)

• Brahe (1546 - 1601)

• Galileo (1564 - 1642)

• Kepler (1571 - 1630)

Figure 1.4 - Nicholas Copernicus 1473 - 1543

Figure 1.5 - Retrograde Motion

Figure 1.6 - Galileo Galilei 1564 - 1642

Figure 1.7Galilean Moons

Figure 1.8a - Venus PhasesSun-centered model

Figure 1.8b - Venus PhasesPtolemy’s model

Figure 1.9 - Johannes Kepler 1571 - 1630

Figure 1.10Tycho Brahe1546 - 1601

Kepler’s laws ofplanetary motionKepler’s laws ofplanetary motion

• 1st law - elliptical orbits

• 2nd law - equal areas in equal times

• 3rd law - P2 proportional to a3

Figure 1.11 - Ellipse

Figure 1.12Orbital Properties

Figure 1.13 - Kepler’s Second Law

Figure 1.14 - Astronomical Unit

Figure 1.15 - Isaac Newton 1642 - 1727

Newton’s Three Laws of MotionNewton’s Three Laws of Motion

1. Motion remains constant unless force acts

2. Force = mass X acceleration3. Forces occur in pairs on two bodies

Figure 1.16Newton’s First Law

Newton’s Law of GravityThe force of gravity is

Newton’s Law of GravityThe force of gravity is

• Stronger with larger masses• Stronger with smaller distances

Figure 1.17 - Gravity

Figure 1.18 Gravitational Force

Figure 1.19 Sun’s Gravity

Figure 1.20 - Center of Mass

Figure 1.21 Orbits