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having the earth as the center


Polish astronomer who produced a workable model of the solar system with the sun in the center (1473-1543)


Proposed a geocentric model


having the sun as the center

Big Bang Theory

the theory that proposes that the universe originated as a single mass, which subsequently exploded

Spiral galaxy

galaxy that looks like a giant pinwheel spinning through space

Elliptical galaxy

a galaxy shaped like a round or flattened ball, generally containing only old stars

Irregular galaxy

A galaxy that goes not have the a regular shape.

Doppler Effect

the apparent change in frequency of electromagnetic or sound waves caused by the relative motions of the source and the observer

red shift

the change in the wavelength of light due to an object moving away from the observer.

blue shift

An increase in the measured frequency of light from an approaching source.

light year

the distance light travels in one year


bending of a ray of light


n. The throwing off or back of light, heat, sound, or any form of energy that travels in waves.

convex lens

a lens that is thicker in the middle than at the edges and bends light rays towards one another

concave lens

a lens that is thinner in the middle than at the edges


the number of complete wavelengths that pass a point in a given time


the spinning of an object on its axis


the act of splitting off into different directions


the state of separate elements joining or coming together

potential energy

Energy that is stored and held in readiness

kinetic energy

Energy in motion


The rate at which velocity changes


the movement of an object around another object

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