9:17:09 Light and Telescopes

9:17:09 Light and Telescopes - LightandTelescopes...

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Light and Telescopes 17/09/2009 07:31:00 How does light tell us the temperature of planets and stars? Thermal Radiation o Most objects emit thermal radiation, including; you, planets, stars, etc. o An objects thermal radiation spectrum depends on only one property:  its temperature Two Properties of Thermal Radiation 1. Hotter objects emit more light at all frequencies per unit area 2. Hotter objects emit photons with a higher average energy Spectroscopy Spectrograph : instrument that separates light by its wavelength o Uses the principles of diffraction and refraction o Prism o Can make similar measurements with radio, infrared, UV, and x-ray  light  Different chemical elements have different spectrums Lines come from the physics of atoms Lines at different wavelengths for different elements because their atoms are  set up different Lines are important- determining what kind of elements are present by 
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9:17:09 Light and Telescopes - LightandTelescopes...

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