Photo credit: Earth from Apollo 16, April 1972. Artist NASA. (Photo by Heritage Space/Heritage Images/Getty Images) – Representative Cover Image Source: NASA astronaut Bob Behnken (Photo by Joe Raedle/Getty Images)
Photo credit: Representative Cover Image Source: (L) A young woman is outdoors on a sunny day, shading her eyes with her hand as she looks upward (Stock photo/Getty Images); (R) Hot Sun warming the Earth (Stock Image/Getty Images) – Array
Photo credit: Representative Cover Image Source: The “Door to Hell” (also known as the Gate to Hell) is a natural gas field in Derweze, Turkmenistan, that collapsed into an underground cavern in 1971, becoming a natural gas crater. (Giles Clarke/Getty Images) – Array
