Wikijunior:Solar System/Glossary

The Solar System

Our Solar System
The Sun
Asteroid belt
Kuiper Belt
Oort Cloud

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.
  • 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.
  • 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.
  • 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.