The document summarizes the history and current understanding of the solar system. It describes early geocentric models of the solar system, with Earth at the center, and the later heliocentric model proposed by Copernicus, with the Sun at the center. Modern science views the solar system as having formed from a large cloud of gas and dust approximately 5 billion years ago, which collapsed under gravity to form the Sun and planets. The solar system now consists of the Sun and eight planets orbiting it, along with their moons, asteroids, and other minor bodies.

1. Chapter 24 Section 1: Our Solar System

2. Pgs. 639 - 645 24:1 The Solar System A. From Earth, other planets are just dots of light Tend to be mistaken for stars Telescopes & space probes revealed so much more B. Early Ideas about the Solar System Earth Center Theory: Early Greeks believed Earth was the Center of the Universe All objects were imbedded in circular paths around us Their order of the universe: Earth Moon Sun Mercury Venus Mars Jupiter Saturn Stars

3. Chapter 24: Section 1 Heliocentric Model 1543: Nicholas Copernicus (Polish Astronomer) Proposed a series of different views: The Earth is a planet The moon revolves around the Earth Planets revolve around the Sun The apparent movement of the sun & planets is due to Earth rotating on it’s axis

4. Chapter 24: Section 1 Heliocentric Model (continued) Galileo Galilei supported Copernicus Showed Venus goes through phases just like the moon Only possible if Venus orbits the sun

5. D. Modern View of the Solar System 10 Planets revolve around our Sun Mercury, Venus, Earth, Mars Asteroid belt (separates inner & outer Planets) Jupiter, Saturn, Uranus, Neptune, Pluto, Xena Most planets have at least one moon orbiting them The sun contains99.86 %of all solar system mass Gravity controls motion and orbital paths

6. Chapter 24: Section 1 Formation of the solar System 5 b.y.a. large cloud of gas, ice & dust existed Began to contract & slowly rotate a. Contraction increased density & rotation b. Gravity began to pull material toward the center c. Density increases = increased rotation & gravity d. Begins to form disk with large center

7. Chapter 24: Section 1 Formation of the solar System 2. Began to contract & slowly rotate (continued) e. Central mass begins to heat up due to contraction Temperatures reach 10 million 0C Hydrogen atoms begin to fuse together forming Helium Fusion occurs, driving the formation of our Sun f. The material outside the central mass forms planets g. This is known as the BIG BANG THEORY

9. The Parts of Our Solar System Parts of Our Solar System Inner Planets:First four planets a. Solid, rock like structures Asteroid belt:band of rocks orbiting the sun Outer Planets:Six planets farthest from the sun a. 4 are made up of mainly lighter element gases Last two are frozen materials The sun is the center of Our Solar System!!

10. Chapter 24: Section 1 Motion of the Planets Johannes Keplerstudied planetary orbits a. Discovered orbits areelliptical Farther from the sun, larger the ellipse Realized the Sun is not exactly central in our solar system b. Planets travel at different speeds through their orbit Planets closer to the sun move faster Planets change speed during their orbit as well