A simplified calendar for the scientific age.  Proposed in an Omni magazine article, this calendar features a regular cycle of 13 months of 28 days each and an origin point that is not based on a religious event.  The months are named alphabetically after scientists, Archimedes to Mendel, instead of for ancient gods and emperors.  The origin point is the moment Neil Armstrong uttered the word Tranquility in the broadcast from the surface of the moon:  "Houston ... Tranquility Base here.  The Eagle has landed."  The day this happened, July 20, 1969 AD, is known as Moon Landing Day in the new calendar, and is not part of any year.  Years begin on Archimedes 1, and the last day of the year, on the anniversary of Moon Landing Day,  is Armstrong Day.  The intercalary day corresponding to February 29th is known as Aldrin Day for the moon walker Edwin "Buzz" Aldrin, and falls between Hippocrates 27 & 28.

Instead of taking as its epoch an event of religious significance and uncertain time, the epochal point of the Tranquility calendar is a non-religious event that is historically significant for all humanity, the timing of which is known to a very high degree of accuracy.

The year 1 A.T. (After Tranquility) began the day after Moon Landing Day, on Archimedes 1, and ended on the first anniversary of the moon landing, Armstrong Day, 1 A.T. (July 20, 1970).  The 34th anniversary of the moon landing will be on July 20, 2003, making it Armstrong Day, 34 A.T.

Months of the Tranquility calendar:

Handy table of dates in the Tranquility calendar:

Source: "Lunar Timekeeper", Jeff Siggins, Omni July 1989, pp. 96-102.