Is dark matter really a purple cloud?
This picture is actually done using "false color imaging." What this
means is that the colors in the picture are not what is actually seen
with the human eye.
Satellite experiments generate an image by assigning each location on its detector to a certain "grid number". The amount of light which then hits this particular location on the detector is counted, and this number (i.e. intensity) is associated with its grid number and telemetered down to Earth. Scientists then assign a color to a certain range of intensity values and plot the information so that it looks like a normal image or photograph. This makes the numbers
easier to interpret.