Planets - Planets: The Imperium of Man is home to over 1,000,000 Human-settled planets scattered across over 100,000 light years of space in the Milky Way Galaxy. Most of these worlds were settled by Humans many centuries before the Great Crusade of the 30th and 31st Millenniums reunited the Human colony planets beneath the rulership of the Emperor of Mankind, though thousands more have been settled in the ten millennia since by Imperial colonists.The Imperium of Man is spread impossibly thin across an estimated two-thirds of the entire Milky Way Galaxy. The volume of space claimed in the name of the Emperor of Mankind contains hundreds of millions of stars, many host to their own planetary systems, and yet there are only an estimated million or so planetary governors occupying the thrones of the Imperium’s worlds.While it is true that some governors rule not just a single planet but an entire star system, and that other worlds have no governor at all, the fact is that the Imperium is stretched so thinly across the void that an interstellar traveller could make their way from one edge to the other, traversing a hundred thousand light years of space, and not once cross paths with another Human being.Instead of being scattered at random, the worlds of the Imperium are clustered around areas settled during the lost age of Mankind's first great wave of expansion into the galaxy during the Age of Technology. Worlds once colonised because of their location or some desirable natural resource have developed into the cores of sectors, many of which have swollen to include two hundred or more star systems.These sectors are connected to one another by relatively stable, if still hazardous, inter-sector Warp routes and the vast, uncharted reaches between each are referred to as Wilderness Space. These unexplored depths harbour all manner of terrors, from ravening pirates to unknown alien empires, as well as untold riches, from long-lost Human colonies to worlds strewn with the wealth of long-extinct xenos species.The Imperium encompasses countless worlds. No one has ever been able to map all of them and no one can truly even say how many there are beyond the figure of 1,000,000 normally cited above. Entire departments of the Adeptus Administratum are devoted to cataloguing the worlds in the Emperor's domains, a never-ending task, for it is in a state of eternal flux. Furthermore, the Adeptus Terra holds that the whole Human race and the entire galaxy are under the Emperor's rule -- the Imperium has a Manifest Destiny to unite Humanity, impose its laws on every Human world and destroy all alien forms of intelligent life.The true scope of the Imperium is, therefore, the entire galaxy, though this is far from actuality. The Imperium jealously guards its territory wherever it can but its sheer size means that it cannot react to every circumstance.Many planets live and die alone, with only the truly great threats commanding the attention of the Adeptus Terra. Worlds are frequently lost to aliens, rebellion or disasters, with news of their destruction sometimes taking centuries to reach Terra. The Imperium’s borders undergo constant change, with new worlds discovered, conquered or colonised and old ones lost to xenos invasion, Exterminatus, daemonic incursion or even to the Warp itself.