side reveals a very subtle grey-blue hue. Note: Because of individual color sensitivity, some people may not be able to see the bluish hue.

For Further Research:

When energized by sunlight, oxygen and nitrogen atoms in the atmosphere re-emit (scatter) light in all direc-Earth's tions, causing the entire atmosphere above us to be lighted by sunlight. Violet light is scattered the most and red light the least (1/10th as much). Because our eyes are not very sensitive to violet light, the sky appears blue.

  • Draw a diagram on a chalkboard or overhead transparency like the one shown below in which you are looking down at Earth from a position far above the North Pole. Measure the difference in atmospheric thickness the Sun's rays must penetrate to reach each location on Earth's surface in the diagram below. Which ray has the greatest distance to travel through the atmosphere to reach surface?
  • Pretend you are standing at each location looking toward the Sun. What color should the Sun be?
  • What is the approximate local time for each location?

Next page Teacher Resources


Last modified prior to September, 2000 by the Windows Team

The source of this material is Windows to the Universe, at http://windows2universe.org/ from the National Earth Science Teachers Association (NESTA). The Website was developed in part with the support of UCAR and NCAR, where it resided from 2000 - 2010. © 2010 National Earth Science Teachers Association. Windows to the Universe® is a registered trademark of NESTA. All Rights Reserved. Site policies and disclaimer.