So I just had a quick question and I was wondering how we convert other waves of the electromagnetic spectrum to visible light waves. For example we use X-ray's or radio waves to see things in space like nebulae that we wouldn't normally be able to see with just visible light waves. But how do we convert those waves to visible light so we can actually see them. I don't know if I'm staying this right but another example that just came to me is pictures of the Sun we see that was taken with radio waves, we see them, which must mean that they were covered into visible light some how, so I was just wondering how, thanks in return =)
It's just as simple as taking the flux at some wavelength (just a number) and using this number to represent a visible intensity.
If you only have one wavelength then you can only get a monochrome picture. However, if you have flux information at more than one wavelength, let's say three, you can use the flux at the longest wavelength to represent red (r), the middle wavelength to represent green (g) and the shortest wavelength to represent blue (b).
Put this together and you have 3 numbers representing a visible rgb signal that can be used to create a picture. Of course there may be lots of fiddling that goes on with the colour balance and the contrast to produce an effective picture, but this is the basic process.