Question: Why are super Novas colourful?

Hi treant,

A supernova is the explosion of a dying star. It makes a BIG MESS. All the different kinds of stuff that are thrown into space give off light of different colours: not only in the colours of the rainbow, but in the colours that are outside the rainbow and that people can’t see with their eyes. (The colours that are bluer than blue are called UV, X-rays, and gamma-rays; the colours that are redder than red are called infrared and radio.)

So supernovae are naturally colourful. And pictures of them — and of lots of other things like galaxies and big clouds of gas — are even more colourful in pictures than they would be if you looked at them with your eyes, because astronomers “look” at them using equipment that can “see” the colours outside the rainbow, and then show those colours as normal colours. So the colours you see on the picture are “not really” the colours coming from the object.

An example. The galaxy Centaurus A looks like this in normal light:
http://chandra.harvard.edu/photo/2002/0157/0157_optical.jpg

In radio (redder than red light) it looks like this:
http://chandra.harvard.edu/photo/2002/0157/0157_radio_continuum.jpg

In X-ray (bluer than blue light) it looks like this:
http://chandra.harvard.edu/photo/2002/0157/0157_xray.jpg

And if you put all three together, you can make a nice colourful picture:
http://chandra.harvard.edu/photo/2002/0157/0157_xray_opt_radio.jpg

Neat, eh?