Black Holes to Blackboards: Getting a Global Sense Despite
assertions by some of a flat Earth, we really do live on a ball
that's spinning through space. Here's a an exercise in
visualizing our rotating planet. The twilight zone is not just
an old television series. It is a real place: the belt around
Earth separating day from night. This globe-encircling band
between light and dark is always present, creating morning or
evening for whichever part of Earth is sliding under it. Most
places on Earth pass through the twilight zone twice a day; the
result is an enchanting hour at dawn and dusk of low sunlight
and long shadows. That special quality of morning and evening
light seen in the zone is produced by sunbeams that were headed
toward Earth but just missed. Captured by our atmosphere and
scattered by gases and particulates, these light rays are
stripped of shorter wavelengths. High clouds catch the light,
revealing its residual reddish hue and creating a continuous
circle of majestic sunsets and promising su