Can someone own the moon?

We have been dreaming about living on the moon for centuries, as this circa 1900 illustration attests. Are you in line for some lunar land? See more pictures of space exploration.
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"Buy land," the old saying goes. "They're not making it anymore." But that’s not entirely true. Across the cosmos, the accretion disks of young suns churn out new land all the time -- if you can wait a few billion years for it to finish baking.

The ether abounds with established acreage, too. As of February 2012, NASA’s planetary property birddog, the Kepler spacecraft, had found 2,326 planetary candidates (61 confirmed), one of them nestled in its star’s habitable zone [source: NASA]. You know what they say in real estate: location, location, location.

Closer to home, Mars offers more than 55.7 million square miles (144.3 million square kilometers) of prime desert property, and Venus balloons to roughly Earth size, but without all of those pesky oceans [source: NASA]. Granted, its runaway greenhouse effect and lead-melting surface temperatures might be a bit blistering for non-Floridians, but at least there are no mosquitoes.

All kidding aside, a space land rush is the most likely thing in the world (or, rather, out of it). As private companies gaze spaceward with dollar signs in their eyes, and as ever more countries pay the cosmic club’s hefty dues, the time to settle questions of space ownership, use and management might arrive sooner than we expect.

Can someone own the moon? Can you stake a claim to any part of a planet, asteroid or other celestial body, or exploit its resources for profit?

The short answer is no. International law and treaties governing space (that’s right -- we actually have space treaties) consider celestial objects the "common heritage of mankind." They argue that space should benefit everyone, and that all peoples should share free access to celestial bodies. Article II of the 1967 Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, including the Moon and Other Celestial Bodies (aka the Outer Space Treaty), settles the issue clearly:

Outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.

This prohibition extends to private parties, although not everyone shares this reading (more on this later) [sources: United Nations; Jakhu and Buzdugan]. It also encompasses the moon’s subsurface, orbital space and approach trajectories -- so no building lunar toll roads.

The documents also require that the moon be used in peace. All parties must preserve it for future generations, keep their activities transparent, avoid getting in each other’s way, warn each other about hazards (such as gun-toting space macaques), offer refuge and aid as needed, and report any resource they might stumble across.

As we’ll see, such legal realities haven’t stopped people from laying claim to the moon, or from selling it off one acre at a time.