Original Air Date: Initial Airdate: March 30, 2007. In this awe-inspiring episode, Oprah dives into one of her greatest fascinations: Planet Earth, the groundbreaking Discovery Channel nature series that redefined how we see our world. The series explores a different corner of the globe  from the deepest oceans to the highest mountains. Oprah shares how the series forever changed the way she sees nature, and she sits down with its narrator, the talented actress, Sigourney Weaver, for a conversation that’s as eye-opening as the series itself. Together, they reflect on the wonder, wisdom, and jaw-dropping surprises the Earth still holds.