1. Formation of the Solar System
Chapter 27

2. Formation of a Planet
1st Solar Nebula: rotating cloud of dust and gas. 2nd Planetesimals: A small body from which a planet originated in the early stages of development of the solar system. 3rd Gravity .

3. Formation of the Solar System Video

4. History of the Models of our Solar System
Aristotle: geocentric model : The sun, the stars, and the planets revolve d around the earth.
(150 CE) Claudius Ptolemy: Change model, thought that planets moved in small circle.
1543 Copernicus: proposed a sun-center model of solar system.
Tycho Brahe ( )- Knew the math needed to make Keplers theory correct.
Johannes Kepler ( )- created three laws of space (Video 25:20)
1608 Galileo Galilei: Observed four moons traveling around the planet Jupiter.
Video Review

5. Johannes Kepler :
1st Law
“The orbit of each planet is an ellipse (elongated circle) and the Sun is at one focus” Kepler proved Copernicus wrong – planets didn’t move in circles
2nd Law
“The line joining the planet to the sun sweeps out equal areas in equal intervals of time
3rd Law
Kepler's Third Law implies that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit. Thus, we find that Mercury, the innermost planet, takes only 88 days to orbit the Sun but the outermost planet (Pluto) requires 248 years to do the same.
(43:00)

6. Gravity and Orbits
Newton developed an understanding of gravity by observing the Moon’s motion.
The force grows stronger in proportion to the product of the two masses, but diminishes as the square of the distance between them. For example, if the distance between Earth and the Moon were twice as great, the gravitational force between them would be one forth as strong.

7. Gravity and Orbits
Law of universal gravitation- Every pair of bodies in the universe attract each other with a force that is proportional to the product of their masses and distance between them.
A review