Why do the spikes that shoot out of stars form perfect crosses? | Science Questions with Surprising Answers— Link
The crossed spikes that you see in some images of stars are not actually parts of the stars. They are imaging artifacts that are created by the telescope itself and are called diffraction spikes. Certain telescopes have a large primary mirror that focuses the incoming beam of light onto a secondary mirror or a sensor that is held over the primary mirror. The secondary mirror diverts the light out of the telescope so it can be seen or further processed. Or, alternately, a sensor held above the primary mirror converts the image to an electrical signal that is delivered to a computer.