1. The Solar System The Planets

2. The Inner Planets  Solar System = a group of objects in space that move around a central star  Planet = a large object that moves around a star  Inner Planets –Mercury (1 st planet from the sun)  Size of the Earth’s moon  Covered with craters like the moon  Gases present but not enough for an atmosphere –Venus (2 nd planet from the sun)  Size of the Earth  Dry with an atmosphere that traps heat (887°F)  Atmosphere weighs 100 times Earth’s  Spins on its axis in the opposite direction of Earth

3. The Inner Planets The Inner Planets –Earth (3 rd planet from the sun)  Largest of the inner planets and has a moon  The only planet with liquid water and can support life  Reflects and absorbs just the right amount of sunlight to sustain life –Mars (4 th planet from the sun)  Has two moons and the largest volcano in the solar system  Red planet because the soil is dark reddish brown  Has dust storms that last months  There is no liquid water now but scientists suspect there may have been once because of the valleys and sedimentary rock.

4. The Outer Planets  Outer planets –Jupiter (largest planet – size of 3 Earths)  Surrounded by a thin ring and at least 16 moons  Atmosphere is active and has caused a 300 year hurricane (circular storm) –Saturn (known for its rings)  Its rings are the widest and brightest  Has at least 18 moons –Uranus (7 th planet from the sun)  Has rings and at least 15 moons  It is a giant blue-green ball of gas and liquid) –Neptune (8 th planet from the sun)  Gas ball with circular storms like Jupiter –Pluto (downgraded to a planetoid)  Smallest and has a rocky surface

5. The Outer Planets The Outer Planets  Asteroids  Asteroids = orbits around the sun and are small and rocky. – –Most asteroids travel between Mars and Jupiter in an area known as the asteroid belt. – –Might be parts of planets that never formed  Comets  Comets = small mass of dust and ice and orbits and sun – –As it gets close to the sun, some ice melts and changes to water vapor. It streams out in a long, glowing tail

6. Moons and Rings  Moons –All planets except Mercury and Venus have a moon –Moons are round and rocky –One of Jupiter’s moons has an active volcano –One of Saturn’s moons has a dense atmosphere that causes it to glow red  Rings –Each gas planet (Saturn, Jupiter, Neptune) has rings –Rings are tiny bits of dust, ice crystals, and small pieces of rock