We’ve all seen the iconic Blue Marble photo of the earth from space, the image that launched a thousand nature essays, but Bill Nelson and Piers Sellers are among the few people who have enjoyed that perspective on the planet in the flesh. Nelson is now a U.S. Senator from Florida, Sellers is a top NASA science official, and this morning, at an Earth Day hearing in my Miami Beach neighborhood, I got to hear the two former astronauts reminisce about the view from 10 million feet. MoreThe Earth Is Changing Rapidly.