Who Speaks for Earth?

Who Speaks for Earth? is the thirteenth and final episode of Cosmos A Personal Voyage. It first aired 21 December 1980 on PBS.

Summary
Carl Sagan reflects on the future of humanity and the question of "who speaks for Earth?" when meeting extraterrestrials. He discusses the very different meetings of the Tlingit people and explorer Jean-François de La Pérouse with the destruction of the Aztecs by Spanish conquistadors, the looming threat of nuclear warfare, and the threats shown by his historically-inaccurate retelling of the destruction of the Library of Alexandria and the murder of Hypatia. He concludes with an overview of the beginning of the universe, the evolution of life, and the accomplishments of humanity and makes a plea to mankind to cherish life and continue its journey in the cosmos.

Cosmos Update
The preliminary reconnaissance of planets with spacecraft, the fall of the Berlin Wall, the end of apartheid in South Africa, and measures towards the reduction of nuclear weapons are discussed.