| A | B |
|---|
| satellite | a body that orbits a planet |
| planet | an object that orbits the sun |
| meteor | a streak of light produced when small objects burn up entering Earth's atmosphere |
| comet | a mixture of dust and ice that leaves a long trail of light as it approaches the sun |
| star | a giant ball of hot gases, mostly hydrogen and helium |
| constellation | a pattern of stars thought to represent an animal, figure or object |
| axis | an imaginary line that passes through Earth's center and the North and South poles |
| rotation | the spinning of Earth on its axis |
| revolution | the movement of Earth around the sun |
| orbit | to revolve around an object |
| solstice | when the Earth tilts farthest or closest to the sun, producing the longest or shortest day of the year |
| equinox | halfway between the solstices, when neither hemisphere is tilted toward the sun |
| force | a push or a pull on an object |
| gravity | the force that attracts all objects toward each other |
| mass | the amount of matter in an object |
| weight | the measure of the force of gravity on an object |
| inertia | the tendency of an object to resist a change in motion |
| Newton's First Law of Motion | an object at rest will stay at rest unless acted on by a force |
| solar eclipse | the moon passing between the Earth and sun producing a shadow |
| lunar eclipse | the moon passing into Earth's shadow |
| umbra | the darkest part of the moon's shadow |
| penumbra | a partial eclipse of the sun |
| tide | the rise and fall of ocean water |
| spring tide | the greatest difference between high and low tide when the Earth, sun and moon are aligned |
| maria | dark, flat areas on the moon |
| neap tide | a tide with the least difference between high and low |
| crater | large, round holes resulting from the impact of meteoriods |
| star chart | a tmap of the stars used to navigate or find constellations |
