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Telescopes - variation low in the earth's atmosphere o...

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Doppler Effect 1. Discovered in 1842 by Christian Doppler 2. Only operates in the direction of the motion 3. Astronomers can use it to measure the speed at which object is approaching (blue shift) or receding (red shift) 4. Astronomers call the speed during the line of sight the radial velocity Change in wavelength = speed of emitter Test wavelength speed of light 5. Only operates in a direct line of sight Earth's Atmosphere 6. Does not transmit all wavelengths of electromagnetic radiation o Refraction - bends light as it enters the earth's atmosphere o Suntillation - "twinkling" of stars is caused by atmospheric density variation high in the earth's atmosphere o "Seeing" - makes stellar images larger than point sources caused by atmospheric density
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Unformatted text preview: variation low in the earth's atmosphere o Scatters Light- more efficient at scattering blue light than red Telescopes Chapter 5 7. Astronomers use telescopes to collect as much light as possible 8. The amount of light collected depends on the diameter of the telescope 9. Magnification is not an important factor o Refractors- use a lens to focus light o Reflectors- use a mirror to focus light Reflectors Problems: 10. Expensive 40 inch in diameter 11. Only support the lens along the outer edges 12. Very long, so requires a large dome 13. Glasses do not transmit UV light o Chromatic Aberration - different wavelengths have different focus positions • This can be reduced using chromatic lenses...
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