PRI's The World: 09/02/2016

President Barack Obama is traveling to China this weekend for the G20 summit. It's being billed as "the most significant gathering of world leaders in China's history." We'll have a preview. Plus, as Obama heads east, he's seeking to cement his legacy on protecting the environment. We take a look at what might happen to that legacy after he leaves office. We also catch up with some scientists studying a rare annular eclipse in East Africa.