Keywords

__**Key Terms**__

The definitions for these terms have come from [|www.wordsmyth.net]

__Asteroid__ A small planet that circles the sun mostly between the orbits of Jupiter and Mars. The size of an asteroid can range from less than one mile to five hundred miles across.

__Atmosphere__ The gases surrounding the Earth or another planet. __Autumn__ The season of the year between summer and winter. __Axis__ The real or imaginary line through the centre of an object, around which an object turns. Earth makes a complete turn on its' axis every 24 hours.

__Comet__ An object in space which travels around the sun. A comet is made up of dust and gas, and sometimes forms a long bright tail. __Corona__ A ring or series of rings seen around a heavenly body, caused by light diffraction due to fine mist or dust in the atmosphere or a region of ionised gases surrounding a star. __Eclipse__ The blocking from view of the sun, a moon, or a planet by another heavenly body. In an eclipse of the sun, the sun is hidden from the Earth's view by the moon passing between the sun and the Earth. __Ecliptic__ The apparent path of the sun as seen from the Earth against the backdrop of stars. __Equator__ The imaginary circle around the middle of the Earth. __Equinox__ Either of the two times of the year when the sun's ray are perpendicular to the Earth's equator, occuring in March and September. During the equinox, day and night are both 12 hours long all over the world. __Full Moon__ The moon when it is on the side of the Earth that is opposite the sun and looks from Earth like a complete circle.

__Galaxy__ A collection of billions of stars and other matter held together by gravity. Earth and the Sun belong to the Milky Way galaxy. They are only tiny parts of this galaxy. __Gravitational Force__ The force that pulls planets, stars or particles toward one another. Gravitional force holds people and other objects to the surface of the Earth. __High Tide__ The highest point reached by a tide, or time of the day when this happens. __Light Year__ A unit of distance equal to the distance light can travel in one year, about six trillion miles. __Low Tide__ The tide at it's lowest level, or the time when this happens. __Meteor / Meteorite__ A piece of matter travelling through space. Upon entering a planet's atmosphere, a meteor can be seen as a bright streak in the sky and is called a meteorite or shooting star. __New Moon__ The phase of the moon when it cannot be seen because it passes directly between the sun and the Earth.

__Orbit__ The curved path in which a planet, satellite or spacecraft moves in a circle around another body. The Earth makes one orbit around the sun each year. __Phases__ A particular stage of development. __Planet__ A large object in outer space that moves around the Sun or another star. There are nine planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. __Rotate__ To turn on or around a central point. __Satellite__ Defintion One: A heavenly body that moves around a planet or another larger body. The moon is a satellite of Earth. Definition Two: A spacecraft that is sent into orbit around a planet or other heavenly body to gather or send back information. __Solar System__ A system that includes a star and all mater which orbits that star, including planets and their moons. __Solstice__ Either of two times of the year when the sun is furthest from the celestial equator, occuring in June and December. __Spring__ The season of the year between Winter and Summer. __Summer__ The season of the year between Spring and Autumn. __Star__ Things that we usually see as points of light in the night sky. The sun is a star. __Tilt__ To move or place so that one side is higher than the other. __Winter__ The season of the year between Autumn and Spring.