phys1160_telescopes.docx - 4.Techniques of Astronomy...

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4.Techniques of AstronomyTelescopesRefracting telescope: Earlier usedoUses a glass lens as its main light collecting elementoCan’t make it larger than 1m or the lens will bend under the weightReflecting telescope: used nowoUses curved mirror (not lens) to focus lightoCan support mirror and can make it very large sizesKey features of telescopesArea of mirror or lensoDetermines light collecting powerLight collecting poweroMore light = see more fainter stars and galaxiesAperture of telescopeoDiameter of the mirror or lensResolving power (Angular resolution)oAbility to see fine detailsoDepends on apertureSO: Lens that’s twice as big will collect four times as much light because its area isfour times largeroEnables us to see more far away into spaceoBIGGER IS BETTERExamples of telescopesMount Wilson, 5m Hale, 10m Keck, EL, AATHistory of observing spaceVisual observation using telescopes (done ages ago when first telescopes came out)oObserve and record with drawings, notesoNegatives: influenced by eyesight, optical illusions, pre-conceptionsPhotographyoUse photographic plates to record images of telescope viewsLong exposures (over hours, nights) to be able to record very faintobjects!

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Term
Three
Professor
Bailey
Tags
Light, Wavelength, radio telescopes

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