| A | B |
|---|
| Gravity | The force of attraction between objects |
| Orbit | The path a planet takes as it moves around the Sun |
| Inertia | The tendency of an object to keep moving Ina straight line |
| Earths revolution | Movement in orbit around the sun |
| Solar eclipse | Moon passes between earth and sun |
| Cause of tides | The gravity of the moon and sun |
| Moon | A natural object that orbits a planet |
| Most asteroids are | Between mars and Jupiter |
| Asteroid belt | Source of solar systems comets |
| Nebula | Cloud of gas where stars form |
| Black hole | An object whose gravity is so strong light can't escape |
| Big Bang theory | Theory how universe started |
| Supernova | An exploding star |
| White dwarf | A small, very dense star |
| Star | An object in space that produces its own energy |
| Galaxy | Huge, far off family of stars |
| Light year | Distance light travels in a year |
| Constellation | A group of stars that form a pattern |
| Spiral galaxy | Galaxy shaped like a pinwheel. Milky Way |
| Elliptical galaxy | Irregular galaxy shaped like an egg |
| Life cycle of our sun (medium sized star) | 10 billion years |
| Troposphere | Lowest layer of the atmosphere. Weather occurs |
| Strength of the pull of gravity | Depends on mass and distance |
