| A | B |
|---|
| Solar system | Sun and the objects travelling around it |
| Gravity | Force of attraction between two objects |
| Inertia | Tendency of a moving object to keep moving in a straight line |
| Lithosphere | The hard, outer layer of earth, about 100km thick |
| Crust | Rocky surface that makes up the top of the lithosphere |
| Hydrosphere | Earth's water |
| Atmosphere | Gases surrounding the earth |
| Orbit | Path of a planet |
| Asteroids | Rocky fragments, between Mars and Jupiter |
| Comet | Mass of frozen gases, dust and rock particles that orbits the sun |
| Newton's Law of Universal Gravitation | Explains the behaviour of planets in the solar system |
| Moon | Causes tides in earth's oceans |
| Apollo 11 | Carried first men to the Moon in 1969 |
| Gravity and Inertia | Keep planets in their orbits |
| Fault | Crack in the crust |
| Geologist | Scientist who studies the earth |
| Magma | Hot, molten rock deep below Earth's surface |
| Lava | Magma that reaches the earth's surface |
| San Andreas fault | Fault in California that causes earthquakes |
| Fold mountains | Montains formed of crumpled and folded layers of rock |
| Fault-block mountains | Formed when tension causes blocks of crust to break apart and move |
