Sun Goes Down. Up Comes A Mystery Here's a question you probably
didn't know was a question: Why is the sky dark at night? My
daughter asked me this about 10 years ago. We were looking up at
the night sky, and she said, "There's lots of stars up there."
And I said, "Yes." Then she said, "Are there stars everywhere?"
And I said there were. Then she said, "Well, if there are stars
everywhere, all of them shining, why don't they fill the sky and
make the sky shiny?" In her mind, the sky, instead of being
dark, should look like this, brightness everywhere. Thirteen-
year-old girls aren't the only ones asking this question. In
1823, a German astronomer, Heinrich Olbers, wondered, "Why is
there dark between the stars?" And ever since, this is called
Olbers' Paradox (which sounds better than My Daughter's Too Hard
To Answer Question.) The key to the paradox is, if you look
closely at any patch of sky, you will see shining stars. If you
look through a telescope, you will see more. The nearer stars
will be brighter, of