The Nature of Light

Electromagnetic radiation emitted by astronomical objects

electromagnetic waves � transfer of energy� by a disturbance

Waves and charged particles

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Two main processes for e-m radiation

Blackbody Radiation

Blackbody (Planck) curves at different temperatures

Radiation laws � apply to astronomical sources

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e-m radiation � stellar properties

Measuring stellar distances

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e-m radiation: spectral lines

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Kirchhoff�s Laws

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