In 1977, two NASA spacecraft left Earth's orbit to afford scientists a closer look at Jupiter and Saturn. And then these celestial-bound twin craft did something even more extraordinary: They transported our message to the universe.
The spacecraft were part of the Voyager Interstellar Mission, and each carried a gold-plated disc designed to survive for a billion years in the hopes an alien civilization might receive it as a greeting. The recorded sounds spanned many possibilities, including the first words uttered to a newborn, greetings in 59 different languages, and music from new and ancient civilizations.
It was Sagan who came up with the idea to add a message to the universe, a "bottle cast into the cosmic ocean," as he put it. Although Sagan's voice isn't heard on the record, he was certainly a part of its creation.
The recording also captured one of science's most famous love stories, the one between Sagan and the project's creative director, Ann Druyan. On the next page, you can discover how their personal voyage began with this interstellar one [sources: Kiger, Krulwich].