I think the wikipedia explanation is much better. https://en.wikipedia.org/wiki/Diffraction_spike https://en.wikipedia.org/wiki/Diffraction_spike One deficien

I think the wikipedia explanation is much better. https://en.wikipedia.org/wiki/Diffraction_spike https://en.wikipedia.org/wiki/Diffraction_spike One deficiency is why apertures (effectively, the support structure in a telescope is an aperture) observe this behavior. > No matter how fine these support rods are they diffract the incoming light from a subject star and this appears as diffraction spikes which are the Fourier transform of the support struts. Like why is that the case? https://en.wikipedia.org/wiki/Airy_disk https://en.wikipedia.org/wiki/Airy_disk Read this if you don't immediately understand why. This is the shape of the image you see when the aperture is circular. This is the Fourier transform of a circular aperture, which, in 1D, is a sinc function. I can't give a straightfoward answer to elucidate further, but if you've done signal processing stuff before you can probably handwavey explain that if there is a Fourier-transform relationship with one function, due to linearity and spacial invariance, you can say that it holds for all functions.