Earth Day, to be observed for the 40th time on April 22, ranks just below motherhood and ahead of baseball and apple pie on the American cultural hit parade. Gaylord Nelson.Photo: Fritz AlbertWorldwide, organizers say a billion people will observe Earth Day this year, making it the largest secular civic event in the world. So why doesn't it get more respect? "Screw Earth Day," says Grist. We should live every day like it's Earth Day, not just be on our best environmental behavior once a year. Wouldn't that be nice? In an ideal world, every day would be Earth Day …