Dr. Thomas Wagner, NASA Program Scientist for the cryosphere, gives a presentation on observing the Earth's Poles in front of the Hyperwall at at a NASA-sponsored Earth Day event at Union Station, Monday April 22, 2013 in Washington. Photo Credit: (NASA/Carla Cioffi)

Dr. Thomas Wagner, NASA Program Scientist for the cryosphere, gives a presentation on observing the Earth's Poles in front of the Hyperwall at at a NASA-sponsored Earth Day event at Union Station, Monday April 22, 2013 in Washington. Photo Credit: (NASA/Carla Cioffi)