| A | B |
|---|
| planet | A celestial body moving in an elliptical orbit around a star. |
| moon | Any planetary body that orbits another planet. |
| sun | A medium sized star that is made up of hydrogen and helium. |
| asteroids | Are made of large pieces of rock that reflect light and orbit the sun. |
| meteroids | Are made of small pieces of rock that orbit the sun but may enter the Earth's atmosphere. |
| comets | Are made of ice, dust, gas, and has a visible tail. |
| inner planets | The rocky planets: Mercury, Venus, Earth, and Mars. |
| outer planets | The gas giants: Jupiter, Saturn, Uranus, and Neptune |
| telescope | Instrument used to make distant objects larger. |
| rocket | Designed to propel itself by ejecting exhaust gas from one end to overcome the force of gravity. |
| satellite | An object that revolves around another object. |
| space shuttle | A reusable spacecraft that transports people and materials to and from space. |
| probe | An unmanned spacecraft sent from Earth to explore objects in space. |
| rover | A space exploration vehicle designed to move across the surface of a planet or other celestial body. |
| spacesuit | Protects the astronaut from the dangers of being outside in space. |
| international space station | Earth orbiting satellite research laboratory where astronauts from many countries work and live. |
| gravity | The force that attracts all objects to each other. |
| orbit | The curved path that an object follows as it revolves around a more massive object. |
| axis | The imaginary line drawn through the center of a planetary body. |
| revolution | A year long elliptical orbit around another planet or celestial body. |
| rotation | The spinning of a planet or celestial body around its own axis. |
