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What is a heiligenschein?
Heiligenschein – which means holy light in German – is a phenomenon that occurs when you look down at your shadow and see a glowing light around your head. This can happen when the ground is wet, for example when there is dew on the grass. But it can also happen when the ground is dry. It can happen in other worlds too!
The heiligenschein phenomenon also has many other names, including shadow hiding, oppositional surge, and so on Seeliger effect.
The most common form of heiligenschein occurs when you look down at your shadow on a day when the grass is wet with dew. You may see a slight brightening around your head, as if a halo is reflecting back at you. Do I know what’s going on? In this case, the sun is behind you and the bright sunlight passes through these dew drops and is reflected back to the observer the way it came.
In the video below, notice the shadow of the cameraman’s head and camera below the golfer. There is a brightening around their head that gives them a subtle halo. This is an example of a heiligenschein.
Dry heiligenschein
So how can you see a similar halo effect around your head when looking at your shadow on dry land? A more accurate term is dry heiligenschein. In the book Weather Storm Dunlop describes the effect as follows:
A similar effect occurs on dry grass, trees and other rough surfaces. When looking in the same direction as the sun’s ray, a blade of grass (for example) hides its own shadow, but when looking to the side, the shadows of other blades of grass (or leaves) become visible. This hot spots it can often be seen from an airplane, apparently gliding over the surface of the fields and forests below.
This means that when a light source is directly behind you, such as the sun, the ground in front of you is shadowless. But just a little further away, the objects start to have shadows again. So the place directly in your view without any shadows is brighter and creates a halo-like phenomenon.
If that sounds a bit like the fame phenomenon, that’s because they’re created similarly. The glume is not just a bright point, but an iridescent ring around the antisolar point.
I saw both the dry heiligenschein and the glory from the planes. The first time I saw a dry heiligenschein, I was flying over Chicago and noticed the sparks from cars, buildings, and other objects below reflected in my eye. This bright place traveled with me.
More pictures
Halos on other worlds
But you can see the heiligenschein phenomenon on other worlds too! This is because, of course, the physics of light works the same throughout our solar system.
As seen above, astronauts on the moon took pictures showing a dry heiligenschein. And Japan’s Hayabusa2 probe captured a remarkable image of its own shadow on asteroid Ryugu along with the heiligenschein during its visit. These are places in the solar system with little or no moisture. But the light source behind the observer and the dry, dusty ground still create a halo effect.
Bottom line: Have you ever looked down at your shadow and noticed that it looks like you have a bright halo around your head? That’s a heiligenschein.
Read more: Aircraft glory: What is it and how to recognize it?
Read more: Can you see a full circular rainbow? Everything you need to know
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