In with Elder Scrolls games can The Firemament be found.
BTW is there any big different between this book in different games?

Oblivion and possibly Morrowind, with very little difference.

Oblivion has the constelations, Morrowind only the Gaurdians constelations. They're in a file name sky something.

The book "The Firmament" is in MW. It's the first book you will most likely see, and pick up during the whole make your character part.

There's one on the ground floor of Chorrol Mages Guild in Oblivion as well.