Challenger Glossary

Action: A force (push or pull) acting on an object.

Asteroid: A small, solid body orbiting the sun. Thousands of asteroids orbit the sun in a large belt between the orbits of Mars and Jupiter. Many others exist throughout the solar system.

Astronaut: Person engaged in or trained for space flight.

Astronomy: The scientific study of the Universe , including the solar system, stars, and galaxies.

Challenger: The space shuttle used in eight successful space missions before it exploded 75 seconds after liftoff on January 28, 1986.

Comet: A swarm of solid particles and gases which revolves about the sun usually in an orbit of high eccentricity.

Constellation: A configuration of stars named for a particular object, person, or animal; or the area of the sky assigned to a particular configuration.

Crater: A hole or depression. Most are roughly circular or oval in outline. On Earth most natural craters are of volcanic origin. On the moon most are of impact origin.

Galaxy: A large assemblage of stars; a typical galaxy contains millions to hundreds of billions of stars.

Gravity: The natural force of attraction that exists between all bodies in the universe.

Jupiter: The largest of the gas giant planets , which orbits the sun at an average distance of 778 million km.

Mars: The fourth planet from the sun; the next planet beyond the Earth away from the sun.

Mercury: Planet nearest to the sun in the solar system.

Meteorite: A meteoroid that reaches the surface of the Earth.

Milky Way: The band of stars and other space matter stretching across the sky that can be seen from Earth without a telescope.

Moon: A natural satellite revolving around a planet; the natural satellite of the Earth, visible by reflection of sun light.

NASA: National Aeronautics and Space Administration, a United States federal agency.

Neptune: The gas giant planet located farthest from the sun at an average distance of 4.5 billion km.

Orbit: The path of an object around another object, e.g., planets moving around the sun.

Planet: Any of nine, non-luminous bodies revolving about the sun.

Pluto: The ninth planet from the sun in the solar system.

Probe: A spacecraft, with no humans aboard, designed to study conditions on or near a planet or other celestial body.

Satellite: A body that revolves about a larger one; for example, a moon of a planet.

Saturn: The sixth planet from the sun in the solar system.

Star: A self-luminous sphere of gas.

Sun: The star about which Earth and other planets revolve

Universe: The totality of all matter, radiation and the space.

Velocity: A vector that denotes both the speed and direction in which a body is moving.

Venus: The second planet in distance from the sun in the Solar System