| A | B |
|---|
| artificial satellite | man made equipment that orbits around the earth or moon |
| asteroid | rocky objects revolving around the sun that are too small and numerous to be considered planets. Made from left over solar system material. Located mostly between Jupiter and Mars |
| asteroid belt | the region of the solar system between the orbits of Mars and Jupiter, where many asteroids are found |
| comet | large clumps of ice dust and frozen gases that travel around the sun in long elliptical orbits |
| elliptical orbit | an orbit that is long and flat. Oval or egg shaped |
| Galilean Moons | The name given to Jupiter's four largest moons, Io, Europa, Callisto and Ganymede. |
| Gas Giant | the name often given to the first four outer planets: Jupiter, Saturn, Uranus, and Neptune |
| geocentric system | a description of the solar system that the Greeks believed in which all of the planets revolve around Earth |
| gravity | force of attraction between all object in the universe |
| greenhouse effect | the process by which heat is trapped in the atmosphere by water vapor, carbon dioxide, methane, and other gases that form a "blanket" around the earth or other planetary body |
| heliocentric stystem | a description of the solar system in which all of the planets revolve around the sun |
| Hubble Space Telescope | a space telescope and camera named for a famous astronaut (Edward Hubble) used to study space elements |
| inertia | the tendency of a body to maintain a state of rest or uniform motion unless acted upon by an external force |
| International Space Station | is a facility that orbits earth and is maintained and used by astronauts from 16 different countries |
| meteor | any of the small solid extraterrestrial bodies that hist the earth's atmosphere |
| meteorites | small rocky objects that enter Earth's atmosphere and land on its surface |
| meteoroids | small, rocky objects that orbit the sun in both the outer and inner regions of the solar system |
| natural satellite | objects that orbit the earth or other object that are not man made- the moon is an example |
| nuclear fusion | the combination of the nuclei of small atoms to form a larger nucleus; releases energy. How the sun gets its energy |
| orbit | the path of an object as it revolves around another object |
| osteoporosis | a condition in which the body's bones become weak and break easily |
| project Apollo | final stage of the U.S. space program to reach the Moon, with Apollo 11 landing on the Moon's surface on July 20, 1969 |
| project Gemini | early U.S. space program where one Gemini astonaut team connected with another spacecraft in orbit; also studied the effects of space travel on the human body |
| project Mercury | first U.S. space program that orbited piloted spacecraft around Earth and brought it back to Earth safely |
| revolution | the movement of an object around another object (year) |
| rocket | a jet engine containing its own propellant and driven by reaction propulsion |
| rotation | the spinning motion of a planet on its axis (day) |
| satellite | any object that travels around another object in space |
| Solar System | sun, planets, and all the other objects that revolve around the sun |
| space probe | an unmanned space craft that is launched specifically to explore the unknown |
| space shuttle | a reusable spacecraft with wings for a controlled descent through the Earth's atmosphere |
| Sputnik 1 | the first artificial satellite, was launched by the Soviet Union in 1957 |
| terrestrial planet | one of the dense rocky planets nearest to the sun; Mercury, Venus, Earth , Mars |
