1. Our Solar System Formed about five billion years ago from a giant cloud of gas and debris Gravity caused Earth and other planets to become layered according to density differences in their material.

2. Planets differ from stars: Planets are colder and shine by reflective light Stars generate their own light through nuclear fusion reactions

3. The characteristics of the planets are affected by each planets location in relationship to the sun The Terrestrial planets are small, rocky, and dense – Mercury, Venus, Earth, and Mars – Resemble Earth in size and rocky compostion

4. Venus is the hottest planet

5. Why does Mercury and the Moon have more impact craters on their surface than Earth? The Earth has an atmosphere that protects us. The Earth has weathering and erosion that breaks down the craters on the Earth’s surface.

6. The Jovian planets are large, gaseous, and low density Jupiter, Saturn, Uranus, and Neptune Gas Planets Pluto Farthest from the Sun A special case among the Planets

7. Asteroids, Comets, meteors are components of our solar system Impact events have been correlated with the mass extinction and global climate change Impact craters can be identified on the Earth’s crust

8. Asteroids Located mostly in a belt between the orbits of Mars and Jupiter Tens of Thousands in number

9. Meteors Small solid particles from space that can be caught by Earth’s gravity and dragged down through the atmosphere As they are heated by friction with Earth’s atmosphere, they burn up producing streaks of light.

10. Comets Icy Objects Most originate in a region outside the planets Have an elliptical orbit around the sun Halley's Comet

11. Halley's comet will next appear in the night sky in the year 2062. It orbits the sun every 75-76 years