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As Voyager 1 sped toward the edge of our solar system, it took one last photo that included the blue dot called Earth.
In the event that the Voyagers would make the first encounter with an extraterrestrial being, NASA decided to send a "Golden Record" time capsule, or explanation of where Voyager came from and what our planet is like. Here's the gold-plated record they sent and instructions for how to use it. I guess today we'd send an iPhone and expect the aliens to text us back.
Carl Sagan, the most-recognized astronomer of the 1970s, produced the record. Here is Earth, which is labeled by the contents of our atmosphere.