3 Colour in astronomy images

So far you have focused on brightness, size, shape and structure in astronomy images, but have neglected one of the most important methods for obtaining physical insights from images: the use of colour information. The colour of starlight encodes information about the temperature of a star. Indeed, colour provides clues to a range of physical processes of interest to astronomers.

This section will explore how telescopes record colour in the visible part of the spectrum, and how we can use that information. It will also examine the full range of light information astronomers can access, from radio waves to X-ray and gamma ray images.