Astro Notes1

Astro Notes1 - Astro Notes October 1st Last time...

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Astro Notes October 1 st Last time Telescopes- look at the entire electromagnetic spectrum Universal design issues—Large diameter, D 1. Light gathering 2. Resolving Power D/ (Lambda) wavelength Optical telescopes- “The seeing” – Atmospheic turbulence in primary limit = SPACE (this is why we go) New Technology --- for next generation of telescope Adaptive optics Take a sample of atmosphere by either 1. watching the twinkling of a star 2. pointing a laser into sky and watching its beam (Very Poweful) Use this date to change shape of mirror in real time to compensate for atmospheric turbulence This will blind spy satellites RESULT: Ground based telescopes better (?) than Hubble (Maybe we don’t need telescopes in space.) Radio Astronomy Principal: Dish that collects and focuses radio waves Study concentrated and focused result History of this Started in 1932 Karl Jansky Bell Labs in New Jersey Detected Radio Nose (A hiss) coming from the center of our galaxy Just an antenna, not really a telescope 1936: Grote Reber Built a radio telescope 9.1 m (=30 feet) across (during great depression he was unemployed) !938-1944 “Mapped” the sky in the radio spectrum Worked at Lambda= 1.85m ; got down to lambda = 0.63 m The reason for this was that he didn’t have enough money the first time, then later he had more funds to build a better piece of equipment Not taken very seriously by the scientific community… because
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1. Resolving power. D/ Lambda = 9.1/ 0.63 = 15 2. Compared to the human eye the maximum dimeter of iris = 7mm and the wavelength lambda= 5 x 10 ^-7 3. D/ Lambda for human eye = 14,000 m 4. Thus Grote Rebers telescope was about 1000 times weaker than the human eye. He couldn’t really see anything through the telescope. 5.
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This note was uploaded on 12/01/2009 for the course ASTR 50800 at USC.

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Astro Notes1 - Astro Notes October 1st Last time...

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