Tranquility Calendar in Lojbannic Tengwar
Time Periods
This calendar uses the standard metric second (or snidu, or 
), consisting of 9,192,631,770 vibrations of caesium-133. From this is derived the 60-second minute (mentu, 
), 3,600-second hour (cacra, 
), 86,400-second day (djedi, 
), 604,800-second week (jeftu, 
), and 2,419,200-second month (masti, 
). (A year (nanca, 
) consists of 31,536,000 seconds, or 31,622,400 seconds for leap-years.)
Reference Moment
The center date in history is Moon Landing Day (tumklad, 
, or for short, TKD, tykydy, 
). The actual center point in time is the exact moment the word tranquility is mentioned in the original quote, "Houston, Tranquility Base Here. The Eagle Has Landed." Moon Landing Day has 20 hours, 18 minutes, and 1.2 seconds Before Tranquility and 3 hours, 41 minutes, 58.8 seconds After Tranquility. This approximately lines up Tranquility Calendar days with Greenwich Mean Time, though as the Tranquility Calendar does not use leap seconds, it runs more closely to International Atomic Time (TAI) than to Coordinated Universal Time (UTC).
General Arrangement
A year contains 13 months of 28 days each, plus one or two days that fall outside the months.
Each year on the anniversary of Moon Landing Day there is a special day of the year called Armstrong Day (armstrongyd, 
, or for short, ARD, aburydy, 
). This day has no day of the week. It falls between Mendel 28 and Archimedes 1 of the following year.
In each leap year there is a special day of the year called Aldrin Day (aldrinyd, 
, or for short, ALD, abulydy, 
). This day also has no day of the week. It falls between Hippocrates 27 and Hippocrates 28.
Year names
The year before Moon Landing Day was 1 Before Tranquility (pu lo trankuiliti, 
, or for short, PT, pyty, 
), and the year after was 1 After Tranquility (ba lo trankuiliti, 
, or for short, BT, byty, 
).
Since lerfu strings can be used as numbers, 12 Before Tranquility can be li parepyty (12 in past of Tranquility) and 31 After Tranquility would be li cipabyty (31 in the future of Tranquility).
Leap Years
Leap years are determined on a 400-year cycle, in which 31 After Tranquility is at one end. Every four years is a leap year; except for every 100 years, which is not; except for every 400 years, which is. 31 AT is one of the 400-year leap years; 131 AT, 231 AT, and 331 AT are not leap years; while 35 AT, 39 AT, 43 AT, and so forth are.
Days of the Week
| Friday |
Venus Day |
venusyd |
 |
 |
| Saturday |
Saturn Day |
saturnyd |
 |
 |
| Sunday |
Sol Day |
solyd |
 |
 |
| Monday |
Luna Day |
lunad |
 |
 |
| Tuesday |
Mars Day |
marsyd |
 |
 |
| Wednesday |
Mercury Day |
mercuryd |
 |
 |
| Thursday |
Jupiter Day |
djupiteryd |
 |
 |
Months
| Archimedes |
arkimedesym |
 |
 |
| Brahe |
bra'em |
 |
 |
| Copernicus |
kopernikusym |
 |
 |
| Darwin |
daruinym |
 |
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| Einstein |
ainstainym |
 |
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| Faraday |
faradeim |
 |
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| Galileo |
galileom |
 |
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| Hippocrates |
xipokratesym |
 |
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| Imhotep |
imy'otepym |
 |
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| Jung |
iungym |
 |
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| Kepler |
keplerym |
 |
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| Lavoisier |
lyvuasierym |
 |
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| Mendel |
mendelym |
 |
|
Annual calendar
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| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| 15 | 16 | 17 | 18 | 19 | 20 | 21 |
| 22 | 23 | 24 | 25 | 26 | 27 | 28 |
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| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| 15 | 16 | 17 | 18 | 19 | 20 | 21 |
| 22 | 23 | 24 | 25 | 26 | 27 | 28 |
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| 1 | 2 | 3 | 4 | 5 | 6 | 7 |
| 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| 15 | 16 | 17 | 18 | 19 | 20 | 21 |
| 22 | 23 | 24 | 25 | 26 | 27 | 28 |
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*: On leap years:
followed by
|
Friday, August 26, 2011 AD would be Saturnday, Brahe 9, 43 AT, or
saturnyd bra'em so pi'e vocipyty, or saturnyd bra'em 9 pi'e 43 PT.
And you could say:
lo cabdei cu detri lu saturnyd bra'em so pi'e vocipyty li'u
| Gregorian Date | Tranquility Date |
| July 19, 1968 | Mendel 28, 2 B.T. |
| July 20, 1968 | Armstrong Day, 1 B.T. |
| July 21, 1968 | Archimedes 1, 1 B.T. |
| July 19, 1969 | Mendel 28, 1 B.T. |
| July 20, 1969 | Moon Landing Day |
| July 21, 1969 | Archimedes 1, 1 A.T. |
| July 19, 1970 | Mendel 28, 1 A.T. |
| July 20, 1970 | Armstrong Day, 1 A.T. |
| July 21, 1970 | Archimedes 1, 2 A.T. |
| July 19 | Mendel 28 |
| July 20 | Armstrong Day (except 1969) |
| July 21 | Archimedes 1 |
| October 31 | Darwin 19 |
| December 25 | Faraday 18 (always a Monday) |
| January 1 | Faraday 25 |
| February 28 | Hippocrates 27 |
| February 29 | Aldrin Day |
| March 1 | Hippocrates 28 |