Earth only contains 1066 people.

Earth, Texas.

The only place on Earth officially named Earth.

There are at least two places named Moon

but the Earth only has one astronomical Moon.

Or does it? From September 2006 to June 2007, Earth had an additional Moon

named 2006 RH120. It's a near Earth

asteroid that usually orbits around the Sun but for 13 months

it fell into an orbit around our planet and became

another Moon of Earth. We can call it that because technically

a Moon is just a natural satellite. Something in

orbit around a planet that humans didn't put there.

There's no official minimum size requirement for Moon status.

The Moon, it's a Moon.

Sputnik, space junk, the International Space Station -

not Moons, they are artificial satellites.

Astronomers believe that, most of the time,

Earth has additional Moons. These newcomers don't always stick around that

long and they tend to only be about

a meter in diameter, so we don't always

detect them and they could, less sensationally,

be called temporary asteroid moons. But,

the vagueness of the word Moon means that, yes, technically

Earth usually has more than one

and Earth is booking it. I mean we're moving through space

incredibly quickly. A light year is an almost

unfathomable distance to put in the human terms

but our solar system orbits around the center of the Milky Way

at about 782,000 kilometres an hour.

Which means, that from the perspective of the center of

our galaxy, about every 1300 years

Earth travels an entire light year.

In other words, the Great Pyramid of Giza,

wasn't just built 4500 years ago, it was also built

almost three-and-a-half light years away.

Big deal - what's it all worth?

Could we assign a price to the entire planet? To Earth itself?

Well, Greg Loughman, an astrophysicist at the University of California, Santa Cruz

devised a beautiful equation for assessing the

value of exoplanets we discover.

It considers their habitability, their ease of being studied

and, of course, how much money we've already spent

looking for them. Funny enough, you can solve

for Earth and find out that compared to what we've already spent looking for

exoplanets - and what we know about them - Earth is worth

about five quadrillion dollars.

The History Channel famously stuck to Earth and

rang up all of Earth's resources like water, lumber and granite using the

current market prices they arrived at a total

of seven quadrillion dollars. If you removed and

isolated all of the elements your body contains, and then solved them each

at market price, you could fetch about two thousand dollars.

Reddit user Shady Potato applied this map

to Earth. If we could mine the entire planet, and separate out all of it's

pure elements, and prices didn't change because of that, we could sell it all

for 15.8 sextillion dollars.

Of course calculations like these don't include every single possible

thing earth, or any other planet has to offer,

and they also don't consider supply and demand.

If someone here on Earth, or some extraterrestrial

group of planet shoppers, had quadrillions,

sextillions of dollars, or the equivalent amount of power,

well, they would have the option to shop in a much

larger store. For crying out loud, there are more than 10,000 asteroids right here

near Earth. And just one of them - 433 Eros -

is estimated to contain a half quintillion dollars worth of platinum

alone, and by weight, even more iron.

So to be more realistic, instead of calculating Earth's value

on Earth, let's calculate its value on the

galactic marketplace, or the universal

marketplace. If you, or some hypothetical group of

aliens, shopping for a planet could pick any planet

in the entire Milky Way galaxy, what about Earth would make it

worth anything? The Milky Way galaxy

is estimated to contain a supply of around 100

to 400 billion planets. As far as

Earth analogues go, Kepler space mission data suggests there were probably

40 billion Earth size planets orbiting within habitable zones

of stars in our galaxy. And within the observable universe?

Quadrillions.

So, from a raw materials and habitability stand point, Earth

probably isn't that rare. But Earth

does have some unique selling points.

For one, it's probably the only planet like itself within at least 12 light years.

So its location might be prime real estate

for an intergalactic rest stop or imminent

domain. And secondly, statistically speaking,

life as we know it might not be unique to Earth,

but there probably isn't life elsewhere that formed exactly like it did here

with jaguars, palm trees and hairless bipeds

who made the same buildings and jokes and art and music

that we have. These might be the truest unique selling points for Earth.

Aliens wouldn't have to understand, or appreciate any of it,

if it merely amused them it might be worth purchasing as a sort of

museum, or zoo at the least.

Of course, interstellar planet shoppers wouldn't have

Earth currency to buy it with, and space cash

isn't worth anything here. But

the technology it would take for them to get to us

would likely be at least thousands of years ahead of what we currently have. So,

an equitable trade might be, say, limited use of Earth

in exchange for their knowledge. Or full

use - or abuse - of Earth in exchange for their knowledge

and fair relocation of all

earthlings to some equally habitable exoplanet.

Boy, this type of speculation is totally

sci-fi. But you know what's not? The next part of

establishing Earth's value:

demand.

Despite what Earth has to offer,

despite what makes it unique, and despite National Geographic's list of

ten reasons other life forms might want Earth

so far we have received

0 offers.

The Fermi Paradox formally

phrases this puzzle. With so many friendly to life as we know it

planets out there, many of which have been around longer than

even Earth, why haven't we been visited by,

or heard from, intelligent life yet?

Maybe Earth, and its intelligent life, really are

rare and special. Or maybe Earth

is so typical, so unremarkable, no other intelligent advanced lifeforms

could be bothered to stop by. But this raises another question.

Even if something came by, what makes us think it would

make an offer? Why would it consider our wishes at all?

In Star Trek 4, the aliens wanted to talk to whales

and humans were just an awkward third wheel.

When Thomas Jefferson made the Louisiana Purchase, he didn't ask,

say, squirrels in Nebraska for permission. He just

did it. And all those squirrels were suddenly in America,

without knowing it. For all we know, that

may have already happened to us. Earth could be owned by some larger

interstellar landlord.

Furthermore, this entire question rests on an even more fundamental

assumption, the assumption that other intelligent life forms

share our concept of ownership;

and the belief that physical things can be bought

and sold. Amongst earthlings, human

bartering is pretty unique. Only we have developed

complicated, socially agreed-upon norms, for the barter of

goods, the use of currency for goods, or the concept that you can

own a piece of Earth's surface.

Sure, animals can be territorial, but they haven't developed that into a more rigorous

expansive sense of fair exchange.

And when it comes to an individual owning more things than they could possibly hold

or defend on their own, well, we humans have systems for that.

We can teach some animals to use tokens as currency to exchange for

treats, but left on their own they don't incorporate

economic ideas into their regular social lives. At the most, we observe animals bartering

amongst each other for services -

but not goods. Why? Well, they may lack the cognitive ability required to keep track of

long-term transactional histories. But they also lack

two other extremely important things: communication and enforcement.

Services, like

grooming, are difficult to steal, so animals can easily trade them.

But without a language to facilitate

snitching, non-humans can't easily

report thefts or devise systems for reporting

and punishing violations. Animals create some pretty beautiful things.

Bowerbird nests, Pufferfish circles,

termite mounds, or the dramatic costumes decorator crabs fashion

out of sea floor debris.

But ownership, and the right to buy or sell what you make,

is only as useful as the power you have to enforce it.

And if you don't have enough power, someone or something else will make decisions

for you. For instance, we have decided that animals

don't own the selfies they take.

Three years ago in Indonesia a monkey stole photojournalist

David Slaters' camera. He later retreived the camera and found that the monkey

had snapped these fantastic images.

Slater maintained that he should receive royalties from people who reproduce the images, like

Wikimedia, but US federal regulators recently ruled that since a

non-human animal created these photos, they're

officially in the public domain. They belong to all of us.

The same goes for selfies taken by elephants,

or lambs,

or Asian short-clawed otters, named Musa.

And it's not just selfies at play here, the same goes for paintings made by

chimpanzees

or dog artists.

So, maybe Earth is worth quadrillions

or sextillions of dollars. Maybe it's worth renting

in exchange for technological know-how. But the mere fact that we can conceive of ourselves

selling our own planet is pretty incredible.

I mean, we don't have a deed to planet Earth, we really only own it via finders, keepers.

But we didn't stumble upon Earth like a hermit crab in its shell,

we really just emerged from it. We didn't build Earth,

if anything, its selective pressures built us.

Does that mean Earth is sort of like a womb?

Does that mean us selling Earth would be the same as a child selling his or her

parents?

Well, not really. Because we aren't here

for the purpose of leaving, analogous to

being born. Honestly, the most fitting metaphor might be

not that we are Earth's owners, or children,

or one in the same with it, but rather that we are

Earth's first willful

effluvia.

In the context of the human body,

effluvia are little emissions of things

built-up within. They often make us

giggle and can be gross. And isn't that what we are?

A sometimes messy, stinky presence that has built up

within and will one day inevitably, and to the extent already have,

discharged out into space?

I guess what I'm saying is that putting a price tag

on Earth is all speculation. We don't know if we will never be

Earth's sales person. But what we do know

is that we are Earth's first

fart.

And as always,

thanks for watching.