Let's take Earth's borders on an absurd ride through the Universe, and use what we discover to examine what borders really mean. We think of property lines and boundary lines as enclosing 2D space, but let's say for the sake of argument that they extend right down to the center of the Earth, and infinitely into space.
This is my current southwestern sky. I live in Brooklyn, so there's no tractor, and with 60% sky cover and a fair bit of light pollution, I can really only see Sirius, the brightest stars of Orion, and Jupiter off to the east. But each of these worlds, and the trillion trillion trillion I can't see, are at the zenith—directly overhead—from some other point on Earth.
For Rigel, that is some 800 light years above the Amazon Rainforest in Pará, Brazil. Jupiter is 4.48 astronomical units above the Sahara Desert in Mali's Gao Region. The entire Andromeda Galaxy is a few miles northeast of Redding, California. Perhaps some unknown object in Perseus, maybe as large as a galaxy, is a few megaparsecs above my yard--and thus owned by my landlord. Just kidding, it's federal territory.
If nation-states had the pretense that they extended infinitely (and thank the heavens they don't), all these objects would rotate through national sovereignties as Earth rotates, revolves, and precesses. National borders, projected onto the celestial sphere, would be visible like in this orthographic projection, where each spot on Earth can see every zenith less than 1/4 Earth circumference away.
The Outer Space Treaty of 1967 limits absurd claims like this, naturally enough, as borders are all about resources and power. As far as I'm aware, the only attempted claim that attempted to go around the Outer Space Treaty's language was when 8 equatorial countries claimed in 1971's Bogotá Declaration that geostationary orbits were not, in fact, space, but a natural resource created by the unique characteristic of the planet below. This would have interesting implications, as Big Telecom would owe a great deal of money to countries like Brazil, Indonesia, and the Democratic Republic of the Congo, sovereign over the equatorial orbits that make your internet possible.
Tropical countries would also, by definition, be the joint owners of the sun. Sol is only ever above regions between the Tropic of Cancer and the Tropic of Capricorn. So sometimes it belongs to the United States, but rarely. Countries like Canada and Germany should clearly be paying the light and heat bill to countries in the global South.
All this to say that borders are what we agree on, and we agree on certain constructions of power. The implications are much more real for how we decide that sovereignty goes down, as in toward the deep crust. Companies like Exxon are already drilling at 12.5 kilometers, like the Sakhalin-I project toward the offshore oil and gas deposits in the Sea of Okhotsk. Unlike Deepwater Horizon, Sakhalin-I actually drills on land, then proceeds horizontally to the dangerous profits below the sea.
The principle Cuius est solum, eius est usque ad coelum et ad inferos ("Whose is the soil, it is theirs up to the heavens and to the depths") is often said to apply to personal property. It doesn't, because, as Sprankling argues, all tests of this principle have fallen to more reasonable common use. You are, correctly, unable to control airplanes over your home. The same should be true, according to Spranking, of the depths, for
the deeper the disputed region, the less likely courts are to recognize the surface owner’s title. The emergence of new technologies for use of the deep subsurface—such as
heat mining and carbon sequestration, both of which may help mitigate global
climate change—requires that we develop a new model of subsurface ownership.
Yet national ownership of these volumes is, perhaps, unquestionable. A fascinating article by Stuart Elden,
"Secure the volume: Vertical geopolitics and the depth of power" traces nations' relatively new attempts to do this. It is, of course, projection of power, much like the increased emphasis on sea resources in Exclusive Economic Zones placed in maps of the world. The world looks very different in this map by Rafi Segal and Yonatan Cohen [
original article].
As borders progress in 2D, so in 3D, or so we hope not. The Outer Space Treaty has language that declares space the domain of "cooperation and mutual assistance" for the "benefit of all peoples." It's about time we realize that Earth is part of space too, the only space we have, before all the depths are gone.
I have a little video on the topic here: