Back to Page 1 Vocabulary

Science Unit 1 Space Vocabulary Definitions - Page 2

14. Radiation Energy that is released in electromagnetic waves. These waves vary in strength from the weakest to the strongest: radio waves, infrared waves, visible light, ultraviolet waves, x-rays, and gamma rays
15. Heliocentric model A model of the universe where the sun is at the center. Scientists today believe that the sun is at the center of our Solar system, not the universe. Helio – means sun   Centric – means center
16. Geocentric model: A model of the universe where the Earth is at the center. Ancient people believes that the Earth was at the center of the universe. Geo – means Earth   Centric – means center
17 Elliptical Orbit: When an object in space travels an oval-shaped path. Earth travels in an elliptical orbit around the sun
18: Inertia: The law of inertia says that anything moving will continue to move in the same path, unless another force changes or stops it.
19. Period of Revolution: The time it takes for a planet to make one complete orbit around the sun (or a moon to orbit its planet). This is one year on that planet.
20. Period of Rotation: The time it takes for a planet or moon to make one complete spin on its axis. This is one day on that planet.
21. Nebula: Massive cloud of dust and gas between the stars – It is the birth of a star
22. Nuclear Fusion: Most of the energy produced by the sun is from this chemical reaction in the sun’s core. Hydrogen atoms are joined together to form helium atoms and huge amounts of energy are released from this reaction.