From the book's forward:
Cosmos is a stand-alone solar system generator created in the finest traditions of science fiction. To paraphrase Arthur C Clarke, it isn't an accurate forecast, but rather an “exploration of possibilities”.
Cosmos totally replaces the Campaign Architecture chapter of the GMG. It attempts to make the sweeping discoveries in astronomy, made over the last decade, useful to the SF gamer; presenting new possibilities and a step-by-step guide to creating your own corner of the Universe.
This is not an official book, but a fan created book.