Space Glossary
Aphelion
The point in an orbit when an object is furthest from the Sun.
Asteroid
A small rocky body orbiting the Sun, mostly found between Mars and Jupiter.
Black Hole
A region of space having a gravitational field so intense that no matter or radiation can escape.
Comet
A celestial object consisting of a nucleus of ice and dust and, when near the sun, a 'tail' of gas and dust particles pointing away from the sun.
Constellation
A group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure.
Cosmos
The universe seen as a well-ordered whole.
Eclipse
An obscuring of the light from one celestial body by the passage of another between it and the observer or between it and its source of illumination.
Exoplanet
A planet that orbits a star outside the solar system.
Galaxy
A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction.
Geostationary Orbit
An orbit where a satellite rotates at the same speed as Earth, appearing stationary.
Gravity
The force that attracts a body toward the center of the earth, or toward any other physical body having mass.
Hubble Space Telescope
A space telescope that was launched into low Earth orbit in 1990 and remains in operation.
ISS
International Space Station, a modular space station in low Earth orbit.
Interstellar
Occurring or situated between stars.
Light Year
The distance light travels in one year (approx. 9.46 trillion km).
Meteor
A small body of matter from outer space that enters the earth's atmosphere, becoming incandescent as a result of friction and appearing as a streak of light.
Nebula
A giant cloud of dust and gas in space.
Neutron Star
The collapsed core of a massive supergiant star.
Orbit
The curved path of a celestial object or spacecraft around a star, planet, or moon.
Parsec
A unit of distance used in astronomy, equal to about 3.26 light years.
Perihelion
The point in the orbit of a planet, asteroid, or comet at which it is closest to the sun.
Pulsar
A highly magnetized rotating neutron star that emits beams of electromagnetic radiation.
Quasar
A massive and extremely remote celestial object, emitting exceptionally large amounts of energy.
Red Giant
A dying star in the last stages of stellar evolution.
Rover
A space exploration vehicle designed to move across the surface of a planet or other celestial body.
Satellite
An artificial body placed in orbit around the earth or moon or another planet in order to collect information or for communication.
Supernova
A star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass.
Telemetry
The collection of measurements or other data at a remote or inaccessible point and their automatic transmission to receiving equipment.
Universe
All existing matter and space considered as a whole.
Zenith
The point in the sky or celestial sphere directly above an observer.