I also took a photograph of the Super Moon through net curtain. The weave on the net curtain is fine enough to act as a diffraction grating. There are both vertical and horizontal threads so the light is diffracted up and down by the horizontal threads and then side to side by the vertical threads. The result is the cross pattern. The weave is about 3 stitches per mm so say 0.3mm. Wavelength of light is of the order of 500nm. These figures give a tiny diffraction angle but since the Moon subtends 0.5 degrees, diffraction angle is of that order. The discrepancy is likely to be due to using a wide light source instead of a point source. I need to try it with a laser later.
