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Describe the problems with the Geocentric model of the universe
- 1. The stars moved around a fixed Earth.
- 2. Could not explain retrofrad motion or phases of Venus.
Describe the Heliocentric model of the universe
- 1. Planets, including Earth, orbit the Sun.
- 2. Phases of Venus and retrograd motion coud be explained in this model.
Describe retrograd motion
- 1. Retrograde motion is when a planet appears to be moving backwards in it's orbit.
- 2. Copernicus reasoned that planets further away from the sun would move more slowly than closer ones. As a faster planet overtakes the Earth in their rotations, its motion against the stars, as seen from the Earth, reverses.
General facts about Sun
- 1. It's a star, a ball of (mainly) Hydrogen gas.
- 2. 700,000 km in radius.
- 3. Generates heat and light through nuclear fusion.
- 4. Surface temp. 5800K, central temp. 15 million K.
- 5. Hydrostatic equilibrium maintained between pressure and gravity.
Explain Hydrostatic Equilibrium
The pressure is not constant throughout a planetary atmosphere. A balance (equilibrium) is maintained between the outward pressure force and the inward gravitational force.
Hydrostatic Equilibrium equation?
T or F: The orbits of the planets are elipses and lie in, or close to the eciptic plane.
State Newton's Univeral Law of Gravitation
Gravity is a force of attraction between all matter in the universe causing apples to fall from trees and the Moon to orbit the Earth.