Stars in Swindon: diffraction spikes

I was at a christening in Swindon considering the stars at the feet of the Virgin. Stars are always drawn pointed although they are actually spherical balls of hot gas. The problem is diffraction when light enters your eyeball. It's all slightly problematic because the aperture is a circle so you should get concentric circle diffraction with a bright central bit called the Airy Disc. But a dilated pupil would have far too big a diameter to do this. Some sources suggest it is to do with surface tension and the liquid on the surface of the eyeball. A more understandable phenomenon is that of "diffraction spikes" forming spiked rays on photographs of stars through telescopes. The lines are produced by diffraction of light round the struts that hold up the secondary mirrors. http://en.wikipedia.org/wiki/Diffraction_spike