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Satellite An object that orbits a planet
Star A ball of hot gas, primarily hydrogen and helium, that undergoes nuclear fusion
Constellation A pattern or grouping of stars that people imagine to represent a figure or object
Geocentric Term describing a model of the universe in which earth is the center of the revolving planets and stars
Heliocentric Term describing a model of the solar system in which Earth and the other planets revolve around the sun
Ellipse An oval shape,which may be elongated or nearly circular;the shape of the planets’ orbit
Rotation The spinning motion of a planet on its axis
Revolution The movement of an object around another object
Solstice Either of the two days of the year on which the sun reaches its greatest distance north or south of the equator
Equinox Either of the two days on which neither hemisphere is tilted toward or away from the sun
Gravity The attractive force between objects;the force that moves objects downhill
Law of Universal Gravitation The scientific law that states that every object in the universe attracts every other object
Inertia The tendency of an object to resist a change in motion
Eclipse The partial or total blocking of one in the space by another
Umbra The darkest part of a shadow
Penumbra The part of the shadow surrounding the darkest part
Tide The periodic rise and fall of the level of water in the ocean
Spring tide The tide with the greatest difference between consecutive low and high tides
Neap tide The tide with the least difference between consecutive low and high tides
Created by: EC3439