No easy answers? Decision-makers from Kissinger to Rice revisit how the US responded to conflicts from Rwanda to Iraq. Faced with human suffering – who has responsibility to act?

Two astronomers go on a media tour to warn humankind of a planet-killing comet hurtling toward Earth. The response from a distracted world: Meh.

On the eve of Earth Day, a precocious seven-year-old learns about the wonders of the planet from his parents—and a mysterious exhibit at the aptly named Museum of Everything.