A search for “Earth Day” on Flickr brought up a remarkable array of pictures from dirty cities to windmills to castles to things I could not really recognize. And as I perused them, I decided that for today’s photo of the day, I’d keep it simple. This photo, by Jennifer Esperanza shows only clouds, fluffy white clouds hovering in a blue sky. It’s simple, pretty and yet says a lot about why we should think more about protecting this spinning blue ball we call home.