Hey, Vsauce. Michael here. This is Earth as seen from Saturn. That is us right there. And if you look closely, ok, see this little protuberance? That's the Moon. This image was taken by the Cassini spacecraft on July 19th, 2013 at 21:27 Coordinated Universal Time. The thing is, NASA gave the public advanced warning of when it would be taken, which means that this image of Earth was the first ever taken from space that some people on Earth were actually posing for.

Our planet looks so small, insignificant, fragile. I recently attended the premiere of Sky 1's upcoming "You, Me and the Apocalypse" with some cool YouTubers and it got me thinking. In the show, the characters find out that they're only 34 days left before a comet smashes into Earth that's likely to end humanity. They all react in different interesting ways, but what would I do if I found out that there were only 34 days of human history left? Ok, my first priority would be to get back to America to be with my family. But after that? I don't really have a bucket list. Except that is exactly what I would want to spend my last few weeks doing. Making a list to put in a bucket that I would then send far out into space away from Earth's impending vaporization.

The list would contain information about us, all Earthlings. So that if libraries and monuments and YouTube videos were all destroyed, a record would still exist somewhere of what and who we were. Like a stone thrown into a lake, the ripples your life causes last long after you vanish, the tree you planted is climbed by future generations, the books you donated inform future readers. But what if it's not just your stone that vanishes, but the entire pond? Perhaps it's arrogance or vanity, but getting cosmic messages in a bottle out there, before the end, diversifies our archive and gives a better chance for future alien visitors, or whatever is left of humanity, to find out that we were once here, to show what we learned. Maybe even to warn future life forms of what we did or what we didn't prepare for. We have already sent some messages about humanity out there, beyond Earth, and if Earth is completely destroyed, those messages will be all that's left of us. What are they?

Ok, first things first. How do you write something for the future? I mean, the distant future. The message might not be found for millions of years or billions. It might be discovered by an audience that's completely different, not only in language, but in senses? What if they can't see or hear or feel or taste or smell like we do, or at all. What if their bodies destroy the very material we write the message on? What language do you even write it in? Well, in general, math and physics, which are believed to be the same everywhere in the universe, have been what we write outer space bound messages in.

Like the Arecibo message, written by Frank Drake, Carl Sagan and others, which was blasted towards the M13 star cluster in 1974. It's composed of a semi prime number of binary digits conveying some info about us and it should reach the center-ish of the M13 cluster in about 25,000 years, at which point, if something intelligent lives there and detects it, they can respond and their response will return to us another 25,000 years later. We won't be around for that.

But Earth has also been broadcasting its radio and TV signals into space. Currently it's about 200 light-years in diameter. Compared to the Milky Way, it's about this big. Aliens within that bubble could tune in and listen to programs we sent out through our airwaves, but these signals thin out as the bubble expands. Across very large distances they may be essentially impossible to tune into.

Maybe a physical time capsule would be more permanent, but it can't be buried on Earth if Earth is about to be ravaged. A time capsule in orbit might be smart, like LAGEOS-1, a satellite put into orbit in 1976 that allows for very precise laser measurements of positions on