Astrophysics professor Kristine Larsen used clues and hints scattered through the books of J.R.R. Tolkein to create this model of the solar system of the Lord of the Rings universe. As is clearly visible, the solar system takes much inspiration from our own, except a few changes and the different names.
As Kristine Larsen describes it:
One gets an immediate appreciation of just how deeply astronomical ideas are ingrained in the texture and fabric of Middle-earth from a study of the chronology of events in “The Lord of the Rings.” Christopher Tolkien’s edited volumes of the “first drafts” of this classic tale (published as volumes in The History of Middle-earth) are bursting with references to the moon and its phases. It appears that much, if not all, of the internal chronology of Frodo’s journey across Middle-earth was timed by and to the phases of the moon. For example, consider the following section from Tolkien’s own notes from the first draft of the Lothlórien section of FOTR:
Nov. 24 Leave Rivendell
Dec. 6 Hollin (Full Moon)
9 Snows on Caradras
11 reach Moria
13 Escape to Lothlórien (Moon’s last quarter)
14 Go to Caras Galadon
15 Night at Caras Galadon
16 Mirror of Galadrien
17-21 Stay at Caras Galadon (Dec. 21 New Moon)
Dec. 22-31 Remain at Caras Galadon, leave with the New Year (Dec. 28 Moon’s first quarter).
These chronologies were changed many times, eventually settling on the lunar phases of 1941-2 (although unfortunately many references to the phases of the moon were edited out of the final published version).
Tolkien was so “wedded” to his lunar chronology that he sometimes reached impasses in his work. In an April 26, 1944 letter to his son, Tolkien said he had “struggled with a recalcitrant passage in ‘The Ring’,” and then went on to say that “at this point I require to know how much later the moon gets up each night when nearing full, and how to stew a rabbit.” (TTT). A letter to his son six months later spoke of a “most awkward error in the synchronization… of the movement of Frodo and the others” which temporarily halted progress on LOTR. According to Chris Tolkien’s research, it appears to be a problem with Pippin and Frodo both seeing the same full moon from different locations in Middle-earth, and on what date this occurred. Tolkien’s own notes say “Whole of Frodo’s and Sam’s adventures must be set back one day, so that Frodo sees moon-set on morning (early hours) of Feb. 6, and Faramir reaches Minas Tirith on the night of the 7th…. (This can be done by making Frodo and Sam only wander four days in Emyn Muil). The next night Frodo would see from far away the full moon set beyond Gondor and wonder where he was in the mists of the west….”