Stardate

Several different systems for calculating stardates have been used.

Prior to 2265, stardates were based on Earth's calendar. This system used the Earth calendar year as the base unit, with the day (numbered between 01-365/366) following the decimal. For example, Stardate 2233.04 was 4 January 2233, while Stardate 2259.246 was 3 September 2259.

Sometime prior to the U.S.S. Enterprise NCC-1701's Five-Year Mission under Captain James T. Kirk in 2265, the stardate system changed, and was no longer linked to the Earth calendar. This system remained in use until the 24th century.

In 2322, another new stardate system was introduced. This married the previous two systems by having 1000 stardates be equivalent to one Earth year, but remained otherwise independent from the Earth calendar. Each stardate is approximately 8 hours, 45 minutes long, and is subdivided by a decimal; the number of digits following the decimal point can be used to calculate the precise time with great detail. The first day of each "stardate year" (when Stardate x999 becomes Stardate y000, where x and y represent the current "stardate years," e.g. 51999 and 52000) falls on 23 May of each Earth year; the First Contact Day holiday falls on Stardate x868 of each year (e.g. Stardate 54868.6 was 5 April 2377).

Reference Stardates

Also in use during the 23rd and early 24th centuries was the Reference Stardate system. Unrelated to the other stardate systems, the Reference Stardates were also based on the Earth calendar and could be calculated retroactively, but were not widely used. Using the Earth year 2000 as a baseline, Reference Stardates marked centuries ahead of a forward slash, followed by two digits for the year, two for the month, a decimal, and the date (e.g. Reference Stardate 1/5104.16 for 16 April 2151, or -1/6609.08 for 8 September 1966).