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The glossary from Amazing Space, which uses the Hubble Space Telescope's discoveries to inspire and educate about the wonders of our universe, is very thorough.


ASTEROID - a rocky object in space that can be a few feet wide to several hundred miles wide. Most Solar System asteroids orbit in a belt between Mars and Jupiter.
ASTRO a prefix that means "star" in the Greek language.
ASTRONAUT a person who travels in space. The word, 'astronaut' comes from the Greek words meaning "space sailor."
ASTRONOMER a scientist who makes observations and studies planets, stars, galaxies any anything else in space.
a unit of length used by astronomers. One astronomical unit equals the distance from Earth to the Sun: 93 million miles.
ASTRONOMY the study of everything that is or was in space beyond the Earth's atmosphere. Astronomy is the oldest science, dating back thousands of years to when people noticed objects in the sky overhead and  watched how they moved.
ASTROPHYSICS a branch of astronomy. It is the investigation of objects in space by  remote sensing from Earth or its vicinity.
AURORA a glow over the polar regions caused by the interaction between Earth's magnetic field and charged particles from the Sun.
ATMOSPHERE The layer of gases surrounding the earth that has gravity strong enough to prevent the gases from escaping into space.
BIG BANG THEORY a theory that says that the universe began with a super-powerful explosion.
BLACK DWARF - the remains of a white dwarf after it cools.
BLACK HOLE - super dense invisible objects in outer space that form when a massive star collapses from its own gravity. Black holes have such an enormous amount of gravity that nothing, not even light, ca escape from them.
CELESTIAL BODY  - an object that is located in outer space.
COMMANDER often the pilot. Commanders are responsible for the vehicle, the crew, mission success, and safety.
COMET - a small frozen mass of gas, dust, and ice. Comets revolve around the Sun or pass  through the Solar System in elliptical orbit.
CONSTELLATION - groups of stars in that people have imagined to represent various objects or mythical beings
COSMONAUT - The Russian term for an astronaut
CRATER - a hole formed by a meteorite hitting the surface of a planet or a moon.
DARK MATTER - nonluminous (not emitting light or visible) material that cannot be seen in the sky. Dark matter is one of the most mysterious things in the universe. Scientists think that  dark matter occurs everywhere but they don't yet know exactly what it is made of.
ELLIPTICAL - shaped like an egg, but with equal ends.
EMBRYONIC STAR CLOUD - (another name for nebula) huge cocoons of dust grains, gas, and molecules that are the birthplace of stars.
GALAXY - a huge collection of stars, nebulae, star clusters, and dust and gas that measures many light years across. A galaxy's shape can be elliptical, spiral, or irregular.
GALILEO GALILEI (1564-1642) - Italian mathematician, astronomer, and physicist. In 1609, Galileo was the first person to use a telescope to observe the skies. Galileo discovered the rings of Saturn, was the first person to see the four major moons of Jupiter, observed the phases of Venus, and studied sunspots.
GRAVITY -the attractive force of a body. The larger or more dense the body, the greater the gravitational force.
KILOMETER - 1,000 meters. A kilometer equals 0.6214 miles.
LIGHT YEAR -units used t o measure distance in space. One light- year is the distance light can travel in one year, which is about 6,000,000,000,000 (6 trillion) miles, or 9,500,000,000,000 kilometers.
METEOR -a meteoroid that enters the Earth's atmosphere, heats up, and looks like a brief streak of fire in the sky.
METEOR SHOWER - what you might see when Earth passes through the tail of a very old comet. During a shower you might see between 30 - 80 meteors an hour. Two well-known major showers are the Perseid shower, which peaks on August 12, and the Geminid shower which peaks on December 13.
METEORITE - a part of a meteor that does not burn up when it enters the Earth's atmosphere but falls to the Earth's surface.
METEOROID - a piece of stone or metal that travels in space around the sun.
MILKY WAY - The galaxy that contains the solar system.
MISSION SPECIALIST - astronauts in charge of on-board operations. They release satellites into space, operate scientific or engineering experiments, repair satellites and operate equipment in the Shuttle's payload bay.
MOON - one of a planet's natural satellites, generally no smaller than ten miles in diameter. There are more than fifty known moons in the Solar System, including Earth's.
NASA - The National Aeronautics and Space Administration. NASA is in charge of all space programs for the United States.
NAVIGATION - Directing the course of a ship or other craft
NEBULA - (another name for embryonic star cloud) a cloud of dust and gas in space in which a star is born.
NEUTRON STAR - a rapidly spinning, extremely dense star composed of mainly neutrons (parts of an atom)..  Neutron stars are the leftovers of a supernova. They are only about 10 miles across, but are very dense.
OPTICAL TELESCOPE - a telescope that uses mirrors to reflect an image to the observer.
ORBIT - the path followed by an object in space as it moves moves around another object.
PAYLOAD - In space flight, the passengers, crew, instruments, or equipment carried by a spacecraft
PAYLOAD SPECIALIST - professionals from life sciences or physical sciences fields. They can also be skilled technicians who are trained to operate special equipment on the mission.
PILOT - controls and operates the shuttle
PLANET - an spherical object that orbits a central star and reflects the suns light. It's diameter can vary but is usually between 1,000 and 100,000 miles.
PULSAR - Pulsars are thought to be rapidly rotating neutron stars with very strong magnetic fields. Bursts of energy are detected on earth from a pulsar at spaced intervals of several seconds or less.
QUASAR - Quasars are not stars. They are galaxies traveling away from us at tremendous speeds.
RADIO TELESCOPE - a telescope that studies planets, star, galaxies and other astronomical objects by using the radio waves they emit. These waves are longer than light waves and need very large antennas or arrays of antennas to capture them.
RADIO WAVE - electromagnetic radiation. Other types of electromagnetic radiation are heat, light, and X-rays.
RED GIANT - a star that becomes cooler, swells and glows with a red color. This happens after a medium-sized star has used up all its energy and begins to collapse.
REFRACTOR - a telescope in which the main light gathering element is a lens, known as the objective, or object lens.
REFLECTOR - a telescope in which the main light gathering element is a mirror.
REMOTE SENSING - the process of collecting information with instruments that record various forms of energy.

-the orbital motion of one object around another. The Earth revolves around the Sun in one year. The moon revolves around the Earth in approximately 28 days.

ROTATE -to turn around a center point, or axis, like a wheel turns on a bicycle.
SATELLITE - a small object revolving around a larger object. Satellites can be natural, such as moons, or they can be artificial objects sent into orbit around the earth, such as communication, weather and navigation satellites.
SHOOTING STAR - another name for a meteor.
SOLAR - something having to do with the sun.
SOLAR FLARE - a storm or eruption of hot gases on the sun.
SOLAR SYSTEM - the sun, and all the planets and other objects that orbit around it.
SOLAR WIND - streams of gas particles flowing out from the sun.
SPACE PROBE - an unmanned research spacecraft sent into space.
SPECTROSCOPE - an instrument that breaks up white light from a star into its different colors. This information is used to determine the surface temperature of the star which helps to determine its age.
SPECTRUM - The colors you see when white light is split apart. The order of colors is : violet, blue, green, yellow, orange, and red. A rainbow is a natural spectrum.
SPEED OF LIGHT - Light travels at 186,000 miles per second, or 299,792,458 meters per second. Albert Einstein predicted that nothing can go faster than the speed of light.
SUNSPOT - a dark area on the sun's surface that is cooler than the area around it.
SUPERNOVA - a great explosion that gives off tremendous amounts of light at the end of a star's life cycle. A supernova can become a neutron star or a black hole.
TELESCOPE - an instrument that can make faraway things appear closer. There are optical, reflecting, refracting, radio, and telescopes in space.
UNIVERSE - the space that contains all of the matter and energy in existence.
WHITE DWARF - the remains of an old star after it uses its energy. It is a small, faint, whitish star that is very dense.