1 Lithe: The moon-letters and the moon's broad crescent

"A broad silver crescent" on 1 Lithe

On this day, in 2789 T. A., Thrór, dethroned King of the Mountain, wrote the moon-letters on his map. It was within the last year of Thrór's life before he was slain by Azog.

On this day, in 2865 T. A., the moon-letters became visible for the first time. Thrór's map was in the hands of Gandalf the wizard, but it did not occur to him to hold the map against the moonlight. It may have been a cloudy evening, anyway.

On this day, in 2941 T.A., the moon-letters became visible for the second time. Elrond detected them and read them aloud.

On all three days, the moon was "a broad silver crescent", a description that survived all revisions of "The Hobbit" unscathed. The best fit with the other lunar phases stated in the book is a moon that is 6 days and 9 hours old at 7.00 p.m. of midsummer's eve, with an illumination that is about 45 %, looking like the image given here that I just shot with my daughter's camera on 10.45 p.m. CEST. The deviation of the lunar phase that Elrond saw from that which Thrór saw at the same time of the day in 2789 T.A. is 11.8 hours, clearly a tolerable error margin.

(I cannot give the details of the calculations here; if you are interested, they are all included in my companion volume "The Moon in 'The Hobbit'", ISBN: 149756056X.)

The dates of 2789 and 2865 T.A. emerge from calculating the Callippic Cycle backwards, a period of 76 years after which the lunar phase repeats on the same day, with a deviation of a few hours. In ancient Greece, the Callippic Cycles were applied to base calendars on, with the first year of the first Callippic cycle beginning at the summer solstice of 330 BC. It may be plausible to assume that the Dwarves of Erebor used a similar calendar to devise the moon-letters.