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How do space telescopes work?

  1. Aug 5, 2009 #1
    How do space telescopes work???

    How do all of these space telescopes work with frequencies other than visible light?
    For example, the Spitzer Space Telescope launched by NASA works on the Infrared frequency....but how?
    We can't see anything but visible light, so how does it convert infrared rediation into things we can see in wierd neon colours? Does it actually refract or reflect infrared in the same way that normal telescopes do with light? And if that does happen, how does it happen...because I don't think it will behave like light or do they use special lenses?
    If light travels to us from light years away, do all other EMRs do also? But I thought the EMR spectrum was unique to our sun. And as far as it goes with infrared radiation, (which are just heat radiations, right) they should be absorbed by surrounding dark matter before they reach us, right?
    And these questions are not restricted to only the Spitzer telescope. It is about all the space telescopes, including the Chandra X-ray Observatory, Hubble,etc.
    Any help will be appreciated.
  2. jcsd
  3. Aug 5, 2009 #2


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    Re: How do space telescopes work???

    Light is light, splitting up EMR into UV, visible, IR, XRay, Radio etc are just labels for convenience.

    The Hubble and it's replacements use pretty much the same detector technology over the UV-IR wavelength = silicon semiconductor's, essentially the same as the CCD in your digital camera.
    For longer IR you use slightly different chemicals and need to cool the detector to reduce the background.
    The X-ray camera on chandra also uses CCDs. Normally an x-ray photon hitting a CCD is a problem because it generates a large background signal and so for astronomical cameras you have to be very careful not to use any material (glass) that is slightly radioactive - but for an x-ray telescope the effect is great.

    The colour pictures produced are often 'false color', you make different brightnesses different colours to make them stand out more clearly. Or you show particular energies (ie. resulting from particular chemicals) in a different colour.

    Scientific cameras are monochrome, you take a colored pictures by putting filters in front of them and taking a red, then blue then green picture one after the other - after all the object isn't going to move/change - combine to get a true colour image.
    Last edited: Aug 5, 2009
  4. Aug 5, 2009 #3


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    Re: How do space telescopes work???

    Got a digital camera? Turn it on and point your TV remote at it and push one of the buttons while watching the camera's viewscreen.

    Same thing; we use a sensor to convert a form of EM we can't see into data we can either analyze directly or covert into an image we can see.
  5. Aug 5, 2009 #4


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    Re: How do space telescopes work???

    Why do you assume that just because the human eye can't see something, nothing can? The only reason the eye can see the visible spectrum is because we live around a star that emits the visible spectrum, and our eyes would not have evolved just so we can't see anything.
  6. Aug 5, 2009 #5
    Re: How do space telescopes work???

    We're also lucky that the cis-trans transition energy of organic molecules is in the visual range.

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