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The Moon and Durin's Day, 2941 TA

by Lalaith <>



Synchronising calendars with the real astronomical events is already a sophisticated problem. In Middle-earth, it was worsened by the fact that different nations and species used individual calendars that were difficult to correlate with each other. The Dwarves, for example, once had a lunar calendar that was replaced by a solar one. But since the moon does not orbit Earth within an exact fraction of a solar year, the lunar calendar shifts against the solar one by a couple of days. Locating an important lunar holiday in a solar calendar system therefore poses a little challenge. Calculating Easter Sunday is based upon that very problem.

Another such date is month and day of Durin's Day, the dwarvish New Year, in the solar year 2941 TA. It played a crucial rôle in the historical events and therefore, historians are of course interested in determining it exactly. Unfortunately, the sources do not provide an accurate time-table. Therefore, the determination of Durin's Day in 2941 TA has to be based upon secondary evidence. For an analysis of the individual calendar systems of Middle-earth including the Dwarvish reckoning, see The Reckoning of Time.

Establishing the lunar phases

At midsummer's eve in Rivendell, Thorin Oakenshield declared himself utterly unable to predict Durin's Day: "The first day of the dwarves' New Year is as all should know the first day of the last moon of Autumn on the threshold of Winter. We still call it Durin's Day when the last moon of Autumn and the sun are in the sky together. But this will not help us much, I fear, for it passes our skill in these days to guess when such a time will come again." (H III)

Gandalf and Elrond must have been hardly forced to suppress a chuckle. A simple lunar ephemeris - no doubt available in Rivendell - would have told the Dwarf precisely when to expect the new moon so that he could have set up his observational site at Erebor and wait for a clear sky to observe the setting young moon (no, I do not know what happened to the Dwarvish calendar during extended periods of bad weather). Gandalf's reply "That remains to be seen" (ibid.) was therefore probably given under utmost constraint so as not to insult the honourable Dwarf. And worse: the comment heard from some fellow a few days later about the "very next first moon of autumn - 'and perhaps it will be Durin's Day'" (IV) testifies an astronomical ignorance of such vastness that it cannot be excused any longer even by living underground. We have to assume several reasons why "Gandalf had shaken his head and said nothing" (ibid.)...

HH1 attests that the „next first moon of autumn“ was an error that escaped proofreading. In editions later than 1995 it was finally amended to read „next last moon of autumn“.

Lacking the ephemeris that Elrond for diplomatic courtesy did not supply, we have thus to use whatever observational observations are provided. One lunar phase is recorded quite exactly in H III: at midsummer's eve 2941, the moon was "a broad silver crescent" in the evening. That translates into a late first quarter moon, approximately between 4 and 6 days old, for before it would have been a narrow silver crescent, while later it would have been described as gibbous.

Durin's Day itself assists in narrowing down the lunar phases on the day precise. We know that the Company arrived via barrel in Esgaroth at 22.IX.(FR) and stayed there at least "a fortnight" (H, X). Durin's Day thus occurred at least two days after the new moon of month X., 2941., precisely on the first day of "the last week of autumn at the threshold of winter" (ibid.). Since all data in H are given in Shire Reckoning, there is only one way to reconcile these data: Durin's Day occurred precisely on Monday, 22.X., two days after a new moon at 20.X. The crescent of midsummer's eve was then by consequence a six-day-old moon, the latest possible configuration.

We may set these observations against the quite exact data provided by LR. Two of them will be sufficient to determine the lunar ephemeris(the roman numerals refer to the months of the Shire Reckoning, in contrast to those of the Gregorian calendar):

9.I.3019 TA: "The Moon, now at the full, rose over the mountains." (FR. Six days later, 15.I., the Company reached Moria.)

23.II.3019, Aragorn to Frodo: "And yestereve a new moon came again. Winter is nearly gone."

Drawing a function that links all mentioned observations, we find a surprising result: The orbital period of the moon was in the late Third Age of the Sun about 20 minutes shorter than today, being approximately 29.518 days in contrast to the modern value of 29.530879 days. This difference arises because the moon is gradually slowed down by tidal friction (and at the same time, receding from earth). This should allow even to compute the geological period to which the Third Age belomgs.

The lunar phases of 2941 TA can thus be given like that:

Full Moon:

12.I. 12.II. 11.III. 11.IV. 10.V. 10.VI. 06.VII. 06.VIII. 05.IX. 05.X. 04.XI. 04.XII.

New Moon:

27.I. 27.II. 26.III. 26.IV. 25.V. 25.IV. 21.VII. 21.VIII. 20.IX. 20.X. 19.XI. 19.XII.

The lunar observations of 2941 TA

The following tables give the absolute chronology of 2941 TA (F = Full Moon; N = New Moon).


Lunar phase




Gandalf meets Thorin in Bree (DF)

Beginning of IV.


Gandalf in Ered Luin (DF)



Bilbo leaves home for days (QE)



"Elves‘ New Year" (QE). Around this time Gandalf meets Holman Greenhand in the Shire.



100th anniversary of Thrain's departure for Erebor, never seen again (the date was amended in the second edition of H to fit the Shire Reckoning; the usage of Thursday rather than Friday is likely a slip without significance).

25.IV. Tu


Gandalf meets Bilbo

26.IV. We


The unexpected party

27.IV. 11:00


Leaving Hobbiton

ca. 29.V.


The Stone-trolls

ca. 15.VI.


Arrival in Rivendell

1 Lithe
(midsummer's eve)


Elrond reads the moon-runes

Midyear's Day
(midsummer day)


Leaving Rivendell, hoping for "the very next first moon of Autumn" (IV), i. e. end of VIII.

09.VII. Mo


Captured in Goblin-town

12.VII. Th


Escape from Goblin-town. Eagle rescue.



Arrival in Beorn's Hall



leaving Beorn



Edge of Mirkwood; Gandalf departs

Early VIII.


Meeting of the White Council. Attack on Dol Guldur before 10.VIII.(DF)



Beginning of the season of Yávië/autumn (Imladris calendar).

late VIII.


Imprisoned by the Silvan Elves

21. IX.


Escape from Thranduil's Halls

22. IX.


Arrival in Lake-town; Bilbo's birthday.



Thorin decides to leave Lake-town

ca. 12. X.


fourth day after leaving; camp at Ravenhill

22. X.


Durin's Day, first day of "the last week of autumn"

23. X.


Death of Smaug

26. X.


Elves set out; Roäc informs Thorin of Smaug's death

28. X.


Elves arrive at Lake-town



Beginning of winter in the North. Fili and Kili sent out to retrieve lost ponies



Fili and Kili return; Elves and Men set out for Erebor



Elves and Men in Dale. Scouts examine Erebor



Thorin rejects the claims of Bard and Thranduil

mid XI.


Battle of Five Armies; a few days later leaving Erebor






Yule-tide in Beorn's Hall

2.V. 2942


First night in Rivendell

A day-by-day calendar of 2941 TA is displayed in the accompanying document.


The timeline in TAMe

In TAMe, Fonstad gives 30.X. as Durin's Day. This date is, as she admits, pure conjecture based on assumed travel times and does not correspond to the lunar phases at all. Fonstad felt herself utterly unable to calculate the dwarvish New Year any more precise.

List of Abbreviations