Components of the Universe

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theory

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a unifying scientific explanation that explains a broad range of observations and is supported by experimental results

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origin

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point at which something begins or from which it comes

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universe

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all of space and the matter that is contained in it

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big bang theory

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a theory that says the universe began as a small point and expanded rapidly about 13.7 billion years ago

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hydrogen

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the most common element found in the universe; stars are made of it and use it as fuel

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star

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a self-luminous celestial body consisting of gas held together by its own gravity in which energy is generated by nuclear fusion

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Hertzsprung-Russell Diagram

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a plot of the surface temperature (color) of stars vs. their luminosity

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luminosity

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the intensity (strength) of light from a celestial body that can be used to identify the body's characteristics

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main sequence

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stable stars in the middle of their development that plot along a continuous diagonal belt on the H-R Diagram

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stellar nebula(e)

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large clouds of gas and dust in interstellar space; the location of star formation