How does the Hubble Space Telescope take pictures?
Hubble takes lots of small grey scale images which are assembled into a mosaic.
The Hubble telescope has relatively small charge coupled device (CCD) cameras which are a few megapixels. They only take grey scale images.
A lot of small images are taken, each covering a small area of the sky. Also several images are taken using different wavelength filters. Some of the images are taken in the infra red and ultraviolet which aren't visible to the human eye.
Each of the images is coloured. False colours are used for the invisible wavelengths. The different wavelength images of the same area are overlaid to produce a full colour image.
The small images are assembled into a mosaic which covers the feature which is being imaged.