Greek Cosmology: Geocentric

• physical principles
• experimental evidence
• epicycles: animation
• Ptolemy

Scientific Models

Nicholas Copernicus

• heliocentric model
• retrograde motion explained (animation)

Tycho Brahe

• nova stella discovery; Johannes Kepler & present view (X-ray vision)
• precision astrometry

Johannes Kepler & Kepler's Laws

1. Orbits are ellipses
2. Equal areas in equal times (animation, another animation)
3. P² = a³

• solar system orbit viewer
• inner solar system objects in real time