In this Vsauce video, Michael Stevens runs through the various messages humans have sent into space, as hopeful time capsules for possible alien civilizations. He also discusses the bizarre Library of Babel, a sort of "infinite monkeys typing on infinite typewriters" project that contains all possible written English language (!), in short chunks.
If you're curious what messages we've sent into space—the specifics of what's on them, where they are, and when they'll get to various locations—this is the video for you. Enjoy: