Chapter 6: The Inner and Outer Solar System
Stars (p.C48)
• Were noticed even before telescopes.
• Balls of glowing hot gas.
• Did not change position in the night sky.
Planets (p.C48)
• Objects that changed position from night to night against the stars.
• Large bodies orbiting a star.
• The Sun’s gravity keeps them in orbit.
• There are 8 true planets in our solar system.
Gravity and Mass
• Gravity is the force of attraction between objects that have mass.
• Mass is a measure of the amount of “stuff” in an object.
• Since all objects have mass, gravity acts between all objects.
• The greater the mass of either object, the stronger the gravity between them.
• The strength of gravity between two objects depends on two things: the mass of the objects and the distance between them.
Early Idea of the Solar System (p.C48)
• Ptolemy – ancient Greek astronomer
• Believed Earth did not move
• Though Earth was at the center of the Solar System and the stars, Moon, and Sun revolved around
Earth.
Copernicus Solar System (p.C48)
• Copernicus- Polish astronomer
• Suggested that the Sun was at the center of the universe
• Was very unpopular when it was introduced
Solar System (p.C9)
• The Sun and all of the planets, moons, and other bodies traveling around it.

Asteroids (p.C54)
• Rocky or metallic
• Orbit the Sun
• Too small to be considered a planet
• Some astronomers believe they are material that never combined to form a planet.
Asteroid Belt (p.C54)
• Most are located between the orbits of Mars and Jupiter
• Some travel from Saturn’s orbit, others have orbits that cross Earth’s path .
Asteroid Theories (p.C54)
• Was what caused the dinosaurs to become extinct.
Meteoroids (p.C65)
• Small asteroids
• Some travel to the edge of the solar system
• Others stay within the orbits of the inner planets
• Where they come from
- From material ejected by a passing comet.
- From the asteroid belt
Meteors (p.C65)
• When a meteoroid hits Earth’s atmosphere.
– The meteor rubs against Earth’s atmosphere producing heat.
– This heat causes the meteor to burn.
• Try rubbing your hands together to produce heat.
• Seen as a bright streak of light.
Meteorite (p.C65)
• Any part of a meteoroid that reaches Earth’s surface.
• 3 types:
– Stony – made out of rock
– Metallic – made from metals like nickel and iron or a mixture of metal and rock
– Carbonaceous – rich in carbon
Meteor Shower (p.C65)
• When many meteoroids hit Earth’s atmosphere at the same time.
– Often happens after a comet has traveled past Earth.

• Some occur year after year.
– Perseid Meteor Shower happens around August 11
Comets (p.C64)
• A ball of ice and rock
• Orbits the Sun
Parts of a Comet (p.C64)
• The nucleus is the main, solid part of the comet
• The coma is a halo of evaporated gas and dust that surrounds the nucleus
• The comet's dust tail always faces away from the sun.
A Comet’s Orbit (p.C64)
• As it comes closer to the Sun the comet begins to melt.
• The melted ice and dust becomes the comet’s tail.
• The tail gets pushed away from the Sun from the pressure.
Where a Comet Comes From (p.C64)
• Kuiper Belt
• A region beyond Pluto’s orbit
• Probably contains 40,000 to 70,000 objects with diameters of more than 100 km.
• Oort Cloud
• 100 Kilometers = 62.1371192 Miles
• Surrounds the solar system about 15 trillion km from the Sun.
Hailey’s Comet (p.C64)
• Orbits past Earth every 76 years.
• The last close pass was in 1986, and the next is due in 2061.
What Is Earth Like? (p.C51)
• Special because it is the only planet in the solar system that supports life.
Layers of Earth (p.C51)
• Inner Core
• Outer Core
• Mantle
• Crust (What we live on)
• Hydrosphere (thin layer of water)
• Atmosphere (layer of gases)

Earth’s Atmosphere (p.C53)
• Protects us from small debris from space.
• Made up of:
• Nitrogen (78%)
• Oxygen (21%)
• Other gases (1%)
Atmospheric Layers (p.C53)
• Troposphere
– Nearest Earth’s surface
– Where weather occurs
• Stratosphere
– Ozone helps absorb harmful ultraviolet radiation from the Sun
• Mesosphere
• Thermosphere
Magnetic Field (p.C51)
• The area that surrounds a magnet.
– Invisible lines of force the run from one pole to the other.
• Earth has one as if there were a giant bar magnet buried inside it.
Van Allen radiation belt (p.C51)
• Discovered by the American satellite, Explorer 1
• Acts like a shield, protecting us particles from the Sun.