Current Tranquility Date: Your browser is not able to support Java objects it seems.

Please note that the names of the days of the week and Gregorian months are presented in English. Also note that the mappings from Tranquility dates are to the Gregorian calendar. The author hopes to eventually make this a more international page by being able to provide more mappings in the future.

What is the Tranquility Date?

It is the date represented in the Tranquility Calendar.

What is the Tranquility Calendar?

The Tranquility Calendar is a calendar that has its roots in science. Its center date in history is called Moon Landing Day. The actual center point in time is the exact moment the word tranquility is mentioned in this somewhat famous 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.

The Tranquility Calendar is logically structured so that days of the week do not vary from month to month, and there are no changes in calendar structure based on year (e.g., there is no change from Julian to Gregorian calendars in the past).

The Tranquility Calendar originally appeared in the July 1989 (Mendel 19 A.T.) issue of Omni Magazine in an article written by Jeff Siggins. Here is the ">text of the article posted with permission of the author.

What are the names of the months?

The 13 months of the Tranquility Calendar are named after famous scientists.


What are the names of the days of the week?


How many days are in each of the months?

Each month has exactly 28 days. The first of each month is always a Friday. The twenty-eighth of each month is always a Thursday.

How many days are in each year?

There are 365 days in each year, except for leap years, in which there are 366 days.

How does one resolve the discrepancy that 13 months of 28 days each is only 364 days?

Each year on the anniversary of Moon Landing Day there is a special day of the year called Armstrong Day. 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. This day also has no day of the week. It falls between Hippocrates 27 and Hippocrates 28.

How does the Tranquility Calendar map to the Gregorian?

Gregorian DateTranquility Date
July 19, 1969Mendel 28, 1 B.T.
July 20, 1969Moon Landing Day
July 21, 1969Archimedes 1, 1 A.T.
July 19Mendel 28
July 20Armstrong Day (except 1969)
July 21Archimedes 1
October 31Darwin 19
December 25Faraday 18 (always a Monday)
January 1Faraday 25
February 28Hippocrates 27
February 29Aldrin Day
March 1Hippocrates 28

Is there any software out there that knows about the Tranquility Date?

tranquilityDate.gzcommand line NEXTSTEP 3.3 quad-fat executable (11561 bytes)
tranquilityDate.cC source code that prints the Tranquility date (3975 bytes)