• Question: How do you get data from a telescope?

    Asked by part362paw to Heidi on 9 Nov 2019.
    • Photo: Heidi Thiemann

      Heidi Thiemann answered on 9 Nov 2019:


      Hey, great question!

      So there’s two ways I get data from a telescope:

      1) Taking photos using visible light – called “photometry”.

      With this method, I work out what star I want to look at and put the coordinates of the star into the computer that controls the telescope. I also work out how long I want to observe the star, and what wavelength (or colour) of light I want to see the star in.

      The telescope then moves to the coordinates of the star (we call it “slewing”) and takes photos. The light from the star is collected by a camera (astronomers call these “CCDs” and they’re basically more powerful cameras than in the back of your phone). We see the light from the star as an image is stored on the computer.

      We can get loads of data from this image, and if we observe the star over many nights, we can see how the light from the star is changing.

      2) Splitting light up – called “spectroscopy”.

      This method is a bit different from taking photos using visible light! We start off the same way, putting the coordinates of the star into the computer and moving the telescope to observe the star, but what we do with the light from the star is different.

      Instead of taking photos of the star in the normal way, we “split” the light through a grating or a prism, and we call this a “spectrum”. You’ll have seen something like this before – a rainbow! This is the light from the Sun being split through water droplets in the air, and it splits white light into all the different colours in light.

      So, in a telescope, we split the light from a star into a “spectrum”. Instead of getting photos, we see the “spectrum” as a graph, and from this we can work out what the star is made up of, whether it is moving, and also detect whether there is a planet orbiting that star.

      Hope this makes sense. 🙂

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