Wikijunior:Solar System/Glossary

A glossary of words used in this book:


 * Antimatter: the opposite of normal matter. Not usually found outside of a laboratory. When mixed with matter they cancel each other out and release lots of energy.


 * Arachnoid: a scientific term for something shaped like a spider, like the legend of the weaving contest.


 * Asteroid: a large rocky object that orbits a star, but is too small to be a planet. It is found in space.


 * Astronomer: a person who studies stars and planets. Also a person who explores new planets and solar systems.


 * Astronaut: a person who travels beyond the atmosphere of the Earth.


 * Atmosphere: a layer of gases around a planet.


 * Atom: a very tiny particle that is the basic building block of matter. It is the tiniest thing on Earth.


 * Basalt lava: molten basalt, a kind of rock from a volcano.


 * Belt: A name used for bands of dark-colored cloud layers on Jupiter.


 * Binoculars: a folding pair of small telescopes with an eyepiece for each eye.


 * Carbon dioxide: a gas that animals breathe out and plants take in.


 * Carbonaceous chondrite: A type of meteorite that contains a lot of water and organic compounds.


 * Centaur: an icy planetoid that orbits the Sun between Jupiter and Neptune.


 * Channel: a groove in the surface of something.


 * Comet: a small icy object orbiting a star.


 * Conjunction: when two objects orbiting the same body come closest together.


 * Continent: a huge landmass on a planet, usually made of tectonic plates that have locked together.


 * Convection: a type of movement in a gas or liquid that carries heat toward a cooler location. When the gas or liquid cools, it sinks back down again.


 * Core: the center of a planet or star.


 * Corona: a region of very hot gas that surrounds the photosphere of a star.


 * Crater: a dent in a planet's surface made by a meteorite falling on it.


 * Crust: the outermost layer of a planet's surface.


 * Dwarf planet: a rounded body that is in orbit around the Sun. It is not a moon and it is not big enough to sweep up the other objects along its orbit.


 * Eclipse: the shadow made when one object comes between another object and the Sun.


 * Energy: what you use to do work.


 * Environment: the conditions on a planet.


 * Equator: an imaginary line around a planet, perpendicular to the axis of rotation.


 * Erosion: the slow wearing away of a surface, usually from wind, water, and temperature changes.


 * Galaxy: a huge mix of gas, dust, stars, planets and other objects that are held together by their own gravity.


 * Gas giant: one of the four outer planets made out of giant balls of gas.


 * Gravity: the force that pulls on anything with mass (see the About gravity, mass, and weight section).


 * Hemisphere: one half of a planet's surface.


 * Ice cap: A huge body of ice at the pole of a planet.


 * Lagrange point: the places where the gravity from two orbiting objects balance each other.


 * Lava: molten rock above a planet's surface.


 * Latin: the language of the Roman Empire that was later used by scientists to name things.


 * Mantle: a layer of molten rock below a planet's crust.


 * Maria: a large sea of magma that has cooled into solid rock.


 * Mass: the amount of matter that something is made of (see the About gravity, mass, and weight section).


 * Matter: a scientific word for 'stuff'.


 * Meteor: a small or medium-size rock from space that has entered a planet's atmosphere but has not reached the ground.


 * Meteor shower: a large number of meteors that enter a planet's atmosphere at about the same time.


 * Meteorite: A meteorite that made it through a planet's atmosphere and landed on the ground.


 * Methane: a gas that makes up most of the gas giants.


 * Near Earth asteroid: an asteroid that has an orbit that brings it very close to the earth.


 * Newton: a unit of measurement the describes how hard gravity is pulling you down (see the About gravity, mass, and weight section).


 * Observatory: A special building where astronomers keep their telescopes ready for use.


 * Orbit: the path that an object takes around a larger object.


 * Orbit System: a planet and its moons rotating around a star.


 * Organic compounds: compounds (collections of atoms) containing carbon.


 * Phase: how a planet or moon looks to us at some part of its orbit, when it is lit by the Sun.


 * Planet: the celestial body that has a greater mass than all other objects of the same orbit system together and that describes a well-defined, special orbit around a star.


 * Planetary nebula: a great cloud of gas that was blown off by an old star.


 * Photosphere: the layer of a star that releases light and other energy into space.


 * Prominence: an eruption of hot gas at the surface of the Sun.


 * Provisional designation: a temporary name given to a newly-found object. Later a permanent name may be picked.


 * Radar: radio waves used to find distances to and make maps of things.


 * Regolith: loose soil on the Moon created by rocks hitting the surface at very high speed.


 * Retrograde motion: a rotation that is the opposite way from the rotation of most of the Solar System.


 * Retrograde orbit: an orbit that is the opposite way from the orbit of most of the planets and moons in the Solar System.


 * Ring: A flat, circular band of many small, loose objects that orbit a planet.


 * Rotate: to spin around on an axis.


 * Satellite: an object in a stable orbit around a much larger object.


 * Scarp: a type of cliff.


 * Sidereal day: the time for a planet or moon to rotate so that a distant star overhead is again overhead.


 * Silicate: an object composed mostly of the element silicon, which makes rocks.


 * Shooting star: another name for a meteor.


 * Solar day: the time for a planet or moon to rotate so that the Sun is again overhead.


 * Solar wind: a very hot gas that is being blown away from the Sun at a high speed.


 * Spacesuit: A special sealed suit that protects an astronaut. It has its own air supply so the astronaut can breath, and is insulated against the cold of space.


 * Spectrum: the colored band of light made when white light passes through a prism.


 * Star: a huge ball of gas that is so heavy that it causes nuclear reactions inside itself. This produces heat and light.


 * Sulfuric acid: a strong type of acid that is used in car batteries, and contains the element sulphur.


 * Supergiant: a star near the end of its life that puffs out into a huge body many times larger than a normal star.


 * Surface area: the area on the outside of something.


 * Tectonic Plate: a solid part of the crust that very slowly moves across the surface of a planet


 * Telescope: a system of lenses or mirrors that are used to see distant objects.


 * Terrestrial planets: the four planets closest to the Sun.


 * Tether: A cord that is used to keep two things attached to each other, such as an astronaut to a spaceship.


 * Tide: the rise in the surface caused by gravity from another object, such as the Moon or Sun.


 * Tidal lock: when tides have slowed rotation so that a moon or planet is always facing the same side toward the planet or star.


 * Transit: When astronomers observe one object pass in front of a larger object.


 * Trojan asteroid: an asteroid in the same orbit as a planet or moon that always stays the same distance ahead or behind.


 * Volcanic: something that relates to volcanoes.


 * Volume: the size of a three-dimensional object.


 * White dwarf: a star that has run out of fuel to burn and is slowly cooling off.


 * Zone: A name used for bands of light-colored cloud layers on Jupiter.

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