"exosphere." Definitions.net. STANDS4 LLC, 2013. Web. 17 Apr. 2013. <http://www.definitions.net/definition/exosphere>.
"Science for Kids: Earth's Atmosphere." Ducksters. Jan. 2013. Web. 30 Jan. 2013. <http://www.ducksters.com/science/atmosphere.php>.
“The Layers of Our Atmosphere.” Kids Geo.com. n.d. Web. 17 Feb 2013. <http://www.kidsgeo.com/geography-for-kids/0046-layers-of-the-atmosphere.php>.
What is the exosphere?
The last layer of the Earth's atmosphere is called the exosphere. The word “exosphere” literally means “outer atmosphere,” from the Greek word “exo,” which means outer or exterior. There is no definite end to the exosphere; it just fades off into space. Most satellites (cable TV satellites, cell phone satellites, weather satellites) orbit in this layer.