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The heiligenschein on bedewed reed, around the head of the photographer's shadow
(photo by I. Können-Jongman)
The heiligenschein is seen as a white aureole around its own shadow; it can be best observed on dewy reeds or grass. This phenomenon is reminiscent of the glory, but without its colours and regular structure. It is mainly the result of the dew-drops acting as lenses, projecting a small image of the sun onto the blade behind it. Looking in the same direction as the rays of the sun, one perceives this bright spot in the lens itself amplified to the size of the drop. At some distance from one's shadow, however, the drop shows us only the dark part of the blade in the shadow of the drop. A second cause of the heiligenschein is that, when we watch along the same direction as the sun's rays, we will never see the shadows of grass-blades on other grass-blades Oust as we never see shadows on the full moon; the full moon is after all nine times brighter than the half-moon!). Hence the heiligenschien may also appear on dry grass or even on rough surfaces, although it is considerably weaker than on bedewed grass. On the other hand, astronauts walking on the moon saw a bright heiligenschein: in this case glassy spheres in the and lunar soil take over the role of the dew-drops. Like the diffraction corona, the heiligenschein is un Polarized.
source: Polarized light in Nature