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the study of the universe


time for Earth to make a complete rotation on its axis


an event in which the shadow of one celestial body falls on another

electromagnetic spectrum

all of the frequencies or wavelengths of electromagnetic radiation; all of the forms of energy released from the sun


a division of the year that is based on the orbit of the moon around the earth


the path that a body follows as it travels around another body in space


the change in the sunlit or illuminated area of one celestial body as seen from another celestial body

reflecting telescope

a telescope that uses a curved mirror to gather and focus light from distant objects

refracting telescope

a telescope that uses a set of lenses to gather and focus light from distant objects


the motion of a body that travels around another body in space; one complete trip along an orbit


the spin of a body on its axis


a natural or artificial body that revolves around a planet


an instrument that collects electromagnetic radiation from the sky and concentrates it for better observation


the time required for Earth to revolve once around the sun

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