• Question: What are infrared telescopes and are they similar to radio telescopes?

    Asked by Sylvia.rsc to Stefan, Anna on 17 Nov 2014.
    • Photo: Stefan Lines

      Stefan Lines answered on 17 Nov 2014:

      Telescopes look at different parts of the electromagnetic spectrum (Radio, IR, Visible, X-Ray… etc). So for one, IR telescopes would be looking at much shorter wavelength ‘light’ (Infra-Red) than Radio. But I’m pretty sure Anna will be able to give a much more defined answer as the exact differences!

      I think an interesting additional question might be, Anna – what can we see better with Radio Telescopes? And vice versa? 🙂

    • Photo: Anna Scaife

      Anna Scaife answered on 17 Nov 2014:

      Hey Sylvia – infrared telescopes are telescopes that receive radiation with wavelengths between 0.001 mm to about 0.1 mm. Radio telescopes receive radiation with wavelengths bigger than about 1 mm. The band in-between infrared and radio is called “sub-millimetre”.

      Some telescopes can cover both the sub millimetre and some of the infrared band – like the ALMA telescope (http://www.almaobservatory.org), which works in almost exactly the same way as a radio telescope.

      If you want to look at the top end of the infrared band (shorter wavelengths) then the Earth’s atmosphere becomes a problem and you need to use a satellite. So one big difference is that infrared telescopes are often satellites, whereas radio telescopes are always on the surface of the Earth.

      >>Anna – what can we see better with Radio Telescopes?

      People tend to use infrared telescopes to look at dusty things (dust clouds, young stars which are surrounded by dusty envelopes, dusty disks around young stars). Whereas radio telescopes are used for looking at very energetic objects – active galaxies with supermassive black holes, ionised gas around very massive young stars, relic radiation from the Big Bang… of course there are somethings that you can see in the infrared and in the radio band. Other galaxies that are similar to ours appear in both – because they have dusty stuff and energetic stuff!

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