Eclipse Shadow Cone Over Patagonia . ... Called shadow cones, they are visible because the Earth's atmosphere is not completely transparent, scattering sunlight and hence appearing blue during the day. Shadow cones are particularly dramatic for eclipses near the horizon , as geometry creates a long corridor of sun-blocked air. Visible above is a shadow cone caught during a sunset total solar eclipse visible last month from Patagonia , Argentina . ... NASA Official: Jay Norris. ...