Glossary of Basic Astronomy Terms

Annular eclipse - a type of solar eclipse in which a ring (annulus) of sunlight remains visible.
Asteroid - a "minor planet" ,a chunk of rock smaller than planet-size but larger than a meteoroid, in orbit around a star.
Asteroid belt - a region of the solar system, between the orbits of Mars and Jupiter, in which most of the asteroids orbit.
Astronomical Unit (A.U.) - The average distance from the Earth to the Sun.
Astrophysics - The science of applying the laws of physics to the universe.
Belts - Dark bands around certain planets, like Jupiter.
Black hole - A region of space that nothing, not even light, can escape from.
Coma - The region around the head of a comet.
Comet - A object orbiting the sun that when it gets close to the sun shows a coma and may show a tail.
Constellation - one of 88 areas that the sky has been divided into to make finding a star or other object easier.
Continental drift - The slow movement of the continents across the Earth’s surface.
Core - The center of a star or planet.
Double Star - A binary star; two or more stars orbiting each other.
Dust tail - the dust left behind a comet, reflecting sunlight.
Eclipse - When one "body" (like the moon) passes through the shadow of another.
Fireball - an very bright meteor.
Full moon - The phase of the moon when the side facing the earth is completely lit by sunlight.
Geology - the study of the Earth.
Giant planets - Jupiter, Saturn, Uranus, and Neptune.
Gibbous moon - the phases between half moon and full moon.
Great Red Spot - Thel large red storm going around like a tornado on Jupiter.
Highlands - Places on the moon that are above the level that may have been smoothed by flowing lava.
Light year - the distance that light travels in one year.
Lunar eclipse - When the moon passes into the earth’s shadow.
Meteor - A streak of light in the sky from rock or dust burning up as it falls through the earth’s atmosphere.
Meteorite - An chunk of rock from space after it hits a planet or moon, especially on the earth.
Meteoroid - An chunk of rock from space that is smaller than an asteroid.
New moon - The phase when the side of the moon facing the earth is the side that is not lit at all by sunlight.
One Year - the length of time the Earth takes to orbit the Sun.
Radio telescope - An antenna or set of antennas that is used to detect radio radiation from space.
Shooting stars - Meteors.
Showers - When many meteors enter our atmosphere at once, or almost at once.
Spring tides - The tides of the ocean are at their highest when the earth, moon, and sun are in a line.
Star - a ball of gas that makes its own light and heat because of nuclear reaction in its center.
Tail - Gas and dust left behind as a comet orbits close to the sun. The sunlight makes the tail bright.
Terrestrial Planets - Mercury, Venus, Earth and Mars.
Very Large Array (VLA) - The National Radio Astronomy Observatory’s set of radio telescopes in New Mexico.