AST101H1 Lecture Notes - Lecture 6: Ellipse, Orbital Period, Geocentric Model

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST101H1
• Professor: Netterfield

Document Summary

It doesn"t feel like the earth is moving: stars, sun and moon rise and set everyday, the stars don"t seem to ever change, things fall to earth. Assumptions: the heavens are perfect and incorruptible, circles are perfect. Conclusions: the earth is the center of the universe, everything revolves in circles around it, planets move in circles within circles. Planets move from night to night relative to the stars. The planets don"t follow a uniform pattern relative to the stars. They appear to turn around relative to the stars: this turn around is called retrograde motion. The earth is the center of the universe. The sun is the center of the universe. The apparent motion of the planets are because the inner planets rotate faster than the outside planets. But: it wasn"t perfectly accurate: it was less accurate than ptolemy"s model. Makes extremely precise measurements of the motion of mars. From his data, current models clearly had problems.