Wayne N. White, the lawyer who's specializing on Space law, explains in his article "Interpreting Article II of the Outer Space Treaty", that the Treaty permits states to apply jurisdiction over their space objects, personnel who works on those objects, and zones of safety that are adjoined to the researched space objects and in zones where their citizens are currently holding any activities. Governments have no jurisdiction or authority over other areas of Outer Space or celestial bodies that don't fit the descripted above, therefore they cannot grant or claim permanent property rights for those areas.
In his article "Homesteading the high frontier", published in Ad Astra magazine at fall 2005, Wayne White notice that Article II of the Treaty doesn't mention private appropriation, therefore private appropriation is not forbidden. Also, Article I of the Treaty says that Outer Space is free for use: "Outer space, including the moon and other celestial bodies, shall be free for exploration and use". White also points out that many lawyers believe that space resources have a legal commercial meaning under the Treaty. The analogy that is brought by Wayne in the article is "commercial fishing in international waters: although no one owns the oceans, individuals and corporations can catch seafood and sell it for a profit".
In the 1970's UN COPUOS delegation held negotiations to develop and adopt an "Agreement Governing the Activities of States on the Moon and Other Celestial Bodies" known also as the Moon Treaty or the Moon Agreement (we'll call it "Moon Treaty"). It opened for signature in 1979. The Moon Treaty disapproved any property rights claims and states in Article 11 that celestial bodies and their natural resources are "the common heritage of mankind". The spacefarers could only utilize resources or claim property rights under the international regime which should have been established by the Moon Treaty.
The Moon Treaty did not achieved the acceptance level of signatures so it couldn't get valid. The UN COPUOS committee failed to reach agreement in establishing a new complex space treaty that would effectively regulate property claims about space bodies, and even more - it failed for several times.
Stephen Gorove in his article "Interpreting Article II of the Outer Space Treaty", describes this situation as a lack of wide international law, which would completely regulate the matter of Outer Space bodies' appropriation. For now, every "individual or a private association or an international organization could lawfully appropriate any part of outer space, including the moon and other celestial bodies".
Alan Wasser, the Chairman of The Space Settlement Institute and a former CEO of the National Space Society, and Douglas Jobes, the President of The Space Settlement Institute and a promoter of space exploration and settlement, mentioned in their article "Space settlements, property rights, and international law: could a lunar settlement claim the lunar real estate it needs to survive?", that according to nowadays International Space law, claiming ownership of Outer Space body would be perfectly legal: "Land claims recognition legislation would, therefore, be perfectly legal under existing international law".
This actually allows private persons to claim and own Outer Space lands, while property rights can be admitted by giving the property a permanent title and they do not require actual presence of people or facilities in the areas which title was conferred. It is worth noting, that such actions have significant financial consequence, so a person who does not disposes an appropriate resources can not implement this idea.
There are many people like us , who believe that Space belongs to everyone. Indeed, there was founded a non-profit association, The Space Settlement, while the general purpose of it is to "help promote the human colonization and settlement of outer space". The association proposed an Act, which promotes legal land ownership on Moon, Mars and other Outer Space bodies. The Space Settlement Prize Act says that "the ratification failure of the Moon Treaty means there is no legal prohibition in force against private ownership of land on the Moon, Mars, etc., as long as the ownership is not derived from a claim of national appropriation or sovereignty".
At July 23, 2015, NASA held a teleconference, announcing a new planet discovery - Kepler-452b. Kepler-452b is considered as the Earth oldest cousin, and might be suitable for life. It is near-Earth-size planet and it has right temperatures for water - an essential ingredient for life as we know it. It also has nearly the same temperature and mass as the Earth.
The Outer Space and the Moon Treaties, that were quoted and interpreted above, state that Kepler-452b, as well as other Outer Space bodies that were discovered and will be discovered in future by Kepler space observatory, could not be a governmental property. According the Treaty, they do not belong to any government. This is why we've claimed their appropriation. We were the first to apply legally and regulatory in a supervised way (and as much as we know, the only ones who applied till the time these lines were written) to all of the 9 leading countries, members of UNOOSA: USA, Germany, Russian Federation, France, United Kingdom, Japan, Korea, India and People's Republic of China. The application was made in a detailed and thorough legal way, as it is required by each country regulations and treaties, including international agreements, and according to all regulations and supervision rules.
Therefore, we can now make it clear that we are the owners of Kepler planets both those that have already been discovered and those that will be discovered in the future, and Kepler-452b in particular.