NASA sent out the unmanned Pioneer 10 as a sort of calling card to the universe. It was the first spacecraft to leave the solar system. This plaque was mounted on Pioneer 10 to help aliens figure out something about the beings that launched Pioneer.
So we have a nude male and female. The man raises his hand in the classic "How" position. Even if the aliens don't know this is our way of saying hello, at least they'll be able to check out our opposable thumbs.
There's a couple of diagrams including "a schematic representation of the hyperfine transition of hydrogen, which is the most abundant element in the universe" and "hydrogen spin-flip transition frequency."
Then there's the nifty diagram of our solar system.
This infographic reveals almost as much about the era it was created in as about the location of our home planet.
If it was created today, would the content differ?
Hopefully the aliens will be able to figure it out.