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| | NTIA Special Publication 98-35, Radio Astronomy Spectrum Planning Options, Chapter 1 |
 | | These wavelengths have been measured in the laboratory, and radio astronomers can identify the radiating atoms in a star as hydrogen, helium, carbon, etc., by measuring the wavelengths at which they emit or absorb energy, and comparing these wavelengths with those measured in the laboratory. |
 | | Spectral lines (wavelengths of electromagnetic radiation) are known to be affected by the motion of their source, just like the sound of an emergency vehicles siren increases or decreases in pitch as it moves toward or away from the observer, respectively. |
 | | In the electromagnetic spectrum, long wavelengths correspond to the radio frequency spectrum, intermediate wavelengths to millimeter and infrared radiation, short wavelengths to visible and ultraviolet light, and extremely short wavelengths to x-rays and gamma rays. |
| www.ntia.doc.gov /osmhome/reports/pub9835/Raspchp1.htm (3717 words) |
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