November 08, 2001
If you look at your shadow on grass covered with dew, you can see a phenomenon called the heiligenschein, which is a German word meaning "holy light." It's generally seen as a faint glow around the shadow of your head, but sometimes it can be quite bright, as shown on the photo above. Sunlight that passes through a dewdrop and strikes a blade of grass is reflected back toward the drop, which acts like a lens and returns the light towards the Sun and our head. Benvenuto Cellini, the famous Italian artist of the sixteenth century, saw this brightening about his head and, being the modest soul that he was, assumed that it was a divine sign confirming his belief that he was indeed a genius. So sometimes this phenomena is referred to as Cellini's halo. Most of us who have observed the heiligenschein or Cellini's halo have known beforehand that we're too dull to imagine that this glow has anything to do with our intelligence or divinity. You only see your own "halo" because you only see light that's reflected backward toward the Sun, which must be directly behind you.