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Heiligenschein

To observe a heiligenschein (‘holy light’), look for a dew-covered lawn or meadow in the early morning when the Sun is still very low. You will notice a white glow around the shadow of your head. Each observer will see his or her own heiligenschein.

If you take photographs of a heiligenschein, the glow will be centered on the camera. Hold out your arm, the heiligenschein will be centered on the camera in your hand. The effect is best when a wide-angle lens is used.

The heiligenschein is produced by dew droplets acting as lenses. The droplets are suspended by tiny hairs on blades of grass or other leaves. The hairs keep the droplets away from the surface. The sunlight is brought into focus behind the droplet and is scattered by the leaf in all directions, but the brightest part of it is returned back through the droplet towards our eyes. There is no heiligenschein if there is no background to reflect the light.

The same effect makes animal eyes glow in the dark - the light is scattered back by the retina.
The heiligenschein takes on the colour of the reflected surface, but the heiligenschein appears white because the eye’s colour receptors are oversaturated.

There is another mechanism which contributes to the heiligenschein - the opposition effect. It is caused by shadow hiding (each object hides its own shadow). If the medium is cylindrical like blades of grass or straw, there will be a bright streak instead of a halo. This is why an opposition effect streak may occasionally be observed.


Heiligenschein and dew bow panorama on a wet meadow. Canon Powershot G2 digital camera with wide-angle lens. Processed with Adobe Photoshop Elements. Two exposures were blended manually.

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