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 Earth, but also contains a plaque designed by Carl Sagan, upon

which is written the numbers 1 to 10 in the binary, and the arrangement of the Earth's continents 250 million years ago,

today and their estimated arrangement in 8.4 million years, which is how long we believe

the satellite's orbit will be stable. Drag caused by the thin atmosphere up where it orbits and

influences like solar activity

will eventually cause it to fall back down to Earth, but its plaque will serve as a

time capsule - a message from us today to whatever happens to be alive or

intelligent here on Earth

8 million years in the future. To put that in perspective, the pyramids

were only built about 5,000 years ago. 8 million years ago, there weren't even

humans on the Earth. The latest common ancestor of humans and chimpanzees was around though.

8 million years from today, when LAGEOS returns, what will intelligent life on

Earth look like? If Earth's surface is barren of life at that point, LAGEOS-1

will be alone. But what about satellites in geostationary orbits? These

orbits are far enough out that they're much safer from atmospheric drag and

could remain above Earth much much longer than satellites like LAGEOS.

These satellites are our pyramids. They're smaller than monuments built by past

civilizations, but impervious to anything that might go wrong on the less stable

surface of our planet. If alien archaeologists come by in a billion

years or so, these satellites may be what their alien encyclopedias use as the

picture for the humans article. So far we have erected about 450

of these geostationary monuments. When such a satellite wears down and

ceases to be operational, it takes a lot of energy to slow it down so it can move

out of the way and fall to Earth to burn up in the atmosphere. So instead, they're

usually pushed into what's known as a graveyard orbit.

A shell around the planet where they can be part without interfering with

important operational satellites. It's fitting that we call these graveyard

orbits because tombs are often the most stunning things we have from previous

civilizations. These graveyard orbits are tombs in a way. Not for kings, but for

machines. Junkyards that will out-exist the very societies and people they so

largely define. Luckily, a few contain more than just our craftsmanship. They

also contain a record, like EchoStar XVI, a communications satellite launched into

geostationary orbit in 2012. Aboard it is a silicon disc created by artist Trevor

Paglen, containing 100 images of Earth and Earthlings. Now, unlike LAGEOS,

EchoStar XVI will likely remain in orbit for billions of years,

safe from discord and change down here. But here's the thing. What if our entire

solar system is lost? Or what if life out there doesn't decide to ever visit our

system? Well, in that case, we have sent interstellar messages. At this moment, so

far, there are 11 distinct human made things on trajectories out of the

solar system into interstellar space. They're all related to five probes.

Pioneer 10, Pioneer 11, Voyager 1 and Voyager 2 and New Horizons, the thing

that recently made a Pluto flyby. These objects are our most distant hellos.

Over the next ten thousand, million, billion years, they'll pass close enough

to other star systems, maybe even planets, to possibly be discovered by other

intelligent life forms. We had the foresight to include special messages on

these probes. The Pioneer plaques are attached to Pioneer 10 and 11, which

launched in the early 1970's, were the first human-made objects to

ever be sent on a trajectory to not just leave Earth, but to leave the solar

system entirely. If discovered by other life out there, these plaques, designed by

Frank Drake and Carl Sagan, could be our first chance to say "hello,

we exist," or, depending on how long humanity lasts, our only chance to say

"Hello,

we existed. This is what we were." But will the plaques makes sense to aliens? Many

humans scientists have had trouble deciphering their meaning, but here's

what they say. At the bottom is a map of our solar system with a path showing the

Pioneer probe itself and where it came from. This element has been particularly

criticized for being human centric. I mean, an arrow? Who's to say aliens will know

that this depicts a path and not some structure in our solar system? Also, it's

an arrow. Arrows might convey this way only two civilizations that hunted or

developed pointy projectiles. Anyway. Up here, we define units. You can't tell

aliens about humans or Earth by using seconds, kilometres or light years,

because we made those measurements up. Instead, the plaque uses hyperfine

transitions to communicate distances and time. The hope is that curious

intelligent life forms who find this will understand that this is a hydrogen

atom - one proton, one electron. Hydrogen is the most abundant element in the

universe, so hopefully its properties will be a common point of understanding.

Now sometimes, if you've got enough hydrogen around, you can catch atoms in

the heap transitioning between particles with parallel spins and antiparallel

spins. Now, whenever this transition happens, electromagnetic radiation is

released with a period of about 2.7 nanoseconds and a wavelength of about

21 centimetres. It's hoped that aliens equate this tick mark with these

two units of measurement. For example, the woman is said to be, in binary, eight of

these units tall. 21 centimetres times eight is a 168 centimetres.

You would think that putting the probe itself behind them for scale

would be enough to show our size, but having both might help solidify the

connection. This diagram is meant to show where we live. We are in the middle.

The direction and proportional length of the lines show where distant pulsars are.

A tick-mark near the ends of each line shows the third direction, behind or in

front of the plaque, that the line should go in. In binary, next to each line is the

period of each pulsar. Again, in the time units described above. If aliens

make this connection they could possibly match the periods with the correct

pulsars in real life,

triangulate our position and come say hello.

Also, since the period of a pulsar changes over time, they could use our

observed periods to date back how long ago this plaque was made. So that's how

the plaque works. It kind of feels like we're just sending out a bunch of

science homework to space, but how else can you find common ground with

something that might not resemble you in any way you could even imagine? Despite

heading out first,

the Pioneer plaques are not the first physical messages made by us to go

interstellar.

That title belongs to Voyager 1. Currently moving at 17 km/s, it is

the most far-out thing humans have ever made.

Literally. In about 40,000 years, both Voyagers will pass within less than

two light years of other stars. If aliens find them, or if future

humans find them, a golden record is attached to both that contains information about

humanity. The record is made of gold plated copper with an aluminum cover,

containing some uranium 238. Given its half-life, smart aliens could analyze it

to determine how long ago the record was made. On the record is the inscription to

the makers of music All Worlds All Times. The record contains 116 images, as well

as audio and video recordings of humans, animals, songs and greetings in fifty

five languages. Printed on the record are instructions for playback and info about

us. The hydrogen hyperfine transition unit definition and the Pulsar map,

included on the Pioneer plaques, but the record also comes with a stylus and

platter to play it. Instructions for using the stylus are on the record. This is a

picture of the stylus being used correctly and then in binary using the

transition units, the record tells the aliens that the stylus should go around

the record once every 3.6 seconds to play back correctly and in

total should take about one hour to do so. For the video portion, instructions

are given in a circle. The first video image is displayed, so they know they did

it right.

Also included on the record is a message from then-president of the United States,

Jimmy Carter. There's something vulnerable about the message. It's

delivered to an unknown recipient, like when someone in a horror movie asks

into the darkness "Is anyone there?

Hello?" This is what it says. "We cast this message into the cosmos. It is likely to survive

a billion years into the future, when our civilization is profoundly altered and

the surface of the Earth

may be vastly changed. Of the two hundred billion stars in the Milky Way galaxy,

some, perhaps many, may have inhabited planets and space faring civilizations.

If one such civilization intercepts Voyager and can understand these

recorded contents, here is our message. This is a present from a small, distant

world. A token of our sounds, our science, our images, our music, our thoughts and

our feelings. We are attempting to survive our time, so we may live into

yours. We hope someday, having solved the problems we face, to join a community of

galactic civilizations. This record represents our hope and our

determination and our goodwill in a vast and awesome universe." Are these messages

enough?

Should we send more? Well, why not send everything? We could, if we sent the

Library of Babel.

It's a website built by Jonathan Basile that currently offers everything that

has been or could be written.

Seriously. Divided into pages, it is built to produce and locate on demand any 3200

character combination of English letters and the comma, space and period. Basile

has organized it all into hexagon-shaped rooms, each with four walls of books

containing five shelves with 32 volumes of four hundred and ten pages each.

Everything's arranged in a pseudo-random fashion, so browsing the online library

feels like a treasure hunt. Here's how it works.