Earth Day: How a senator's idea more than 50 years ago got people fighting for their planet

Millions of people around the world will pause on Monday, at least for a moment, to mark Earth Day. It’s an annual event founded by people who hoped to stir activism to clean up and preserve a planet that is now home to some 8 billion humans and trillions of other organisms. Earth Day has its roots in growing concern over pollution in the 1960s. That's when author Rachel Carson’s 1962 book “Silent Spring,” about the pesticide DDT and its damaging effects on the food chain, hit bestseller lists and raised awareness about nature’s delicate balance. But it was a senator from Wisconsin, Democrat Gaylord Nelson, who had the idea that would become the first Earth Day in 1970.