It"s Earth Day today and we are high above the blue marble looking down on the border between Arkansas and Mississippi. Those small, blocky shapes are towns, fields, and pastures, and the teal green is the mighty Mississippi River. Anyone who has flown in the window seat of an airplane and gazed down at Earth below might wonder why the colors in this image look so unreal. That"s because they are. This image was taken in 2013 by Landsat 7, a NASA satellite that uses thermal infrared sensors to help scientists better distinguish flora, fauna, water, and manmade objects. For almost 50 years, NASA has been using satellite imagery to understand how climate change and population growth are affecting our fragile planet. These satellites help NASA see where deforestation and wildfires are happening, where glaciers are melting, and how rising waters are encroaching on cities.