1. The Solar System Target 7: I can explain the theory of the formation of the solar system

2. What was the early belief about our solar system? Astronomers believed that the sun and planets revolved around the Earth—a geocentric universe Astronomers believed that the sun and planets revolved around the Earth—a geocentric universe _____________ = Earth centered _____________ = Earth centered

3. BUT! If the planets move around the Earth, why did some of them seem to sometimes go in reverse? If the planets move around the Earth, why did some of them seem to sometimes go in reverse? Mars exhibits retrograde motion, moving in the opposite direction in the sky Mars exhibits retrograde motion, moving in the opposite direction in the sky

4. http://www.lasalle.edu/~smithsc/Astronomy/retrograd.html

5. In 1563 Nicolaus Copernicus proposed that the Sun was the center of the solar system! In 1563 Nicolaus Copernicus proposed that the Sun was the center of the solar system! _________________ model = Sun centered _________________ model = Sun centered

8. Astronomers’ contributions Copernicus—heliocentric solar system Copernicus—heliocentric solar system Kepler—planets have _____________ orbits with Sun at one focus (Kepler’s 1 st Law) Kepler—planets have _____________ orbits with Sun at one focus (Kepler’s 1 st Law) Kepler's second law of planetary motion describes the speed of a planet traveling in an elliptical orbit around the sun. It states that a line between the sun and the planet sweeps equal areas in equal times. Kepler's second law of planetary motion describes the speed of a planet traveling in an elliptical orbit around the sun. It states that a line between the sun and the planet sweeps equal areas in equal times. Kepler’s third law states the ratio of the squares of the periods to the cubes of their average distances from the sun is the same for every one of the planets. Kepler’s third law states the ratio of the squares of the periods to the cubes of their average distances from the sun is the same for every one of the planets.

10. _________________—discovery of Jupiter’s moons proves that not all celestial bodies orbit Earth _________________—developed laws of gravity to explain planets orbits in 1665

11. Formation of the Solar System! Solar Nebula Theory: Began with a cloud of interstellar gas and dust, which began to: Solar Nebula Theory: Began with a cloud of interstellar gas and dust, which began to: collapse collapse heat up heat up spin (rotate) spin (rotate) and flatten (which is why the planets are in the same plane as the Sun!) and flatten (which is why the planets are in the same plane as the Sun!) https://www.youtube.com/watch?v=PL3 YNQK960Y https://www.youtube.com/watch?v=PL3 YNQK960Y

14. Differences between the planets In the center of the disk the Sun formed, with the planets forming around it according to temperature differences! In the center of the disk the Sun formed, with the planets forming around it according to temperature differences! _____ ______________formed farther away from the Sun where it was cool enough for the gases and ices to collect. _____ ______________formed farther away from the Sun where it was cool enough for the gases and ices to collect. _______________ ___________formed closer where it was hotter and is why they are made up of rock and metal). _______________ ___________formed closer where it was hotter and is why they are made up of rock and metal).