[otoburb]

It seems that if you bought a star earlier then Tlon will "[...] write [Ethereum smart-] contracts that help galaxies and stars distribute their stars and planets" such that the "[...] star owner configures the planet sale contract with two parameters: the price in ether of a planet, and the number of planets available."

Basically, star owners will be handed a mechanism to run their own mini-ICO, where planets represent ICO tokens.

Why would you want to buy a planet from star owner X? I presume the answer lies somewhere in the statement: "Galaxies and stars are network infrastructure. Regular users have planets."