Hi everyone! This is not directly related to Harry Potter, but I found it fascinating and thought I'd share it here.
The Talmud (Chagiga 12a) makes a cryptic statement about the creation of the universe: The Hebrew word "tohu" in the second verse of Genesis, usually translated "formless" or "void," is explained by the Talmud as refering to "the green line that surrounds the entire world." Since the year 300 or so when the Talmud was written, most commentaries give metaphorical or mystical explanations, and most people studying it shrug and move on.
Enter the space shuttle. Take a look at the attached video, which is time-lapse image of the world from the space shuttle. What you'll is, yes, a green line that seems to surround the entire world, apparently at the outer edge of the atmosphere.