As much fun as I was having with the calendar I designed in Star Dates and Calendars, the system is a tad too unworkable. Yes, I can write a computer program to generate dates, but it is no fun to try to calculate those dates in Excel. (And odds are, whoever would be using this system in this world would have designed it for even simpler applications.)

Absolute Dates

Absolute time is kept in an adapted form of Julian Days.

As the standards board was meeting in the late 19th century, This blog entry was made on 2021-04-12, which would be star date 2459317.

If you have a handy Tcl interpreter, you can calculate star dates with the clock command:

clock format [clock scan $date] -format %J

In Excel, you can use the built in date functions. Excel uses a serial date system. Day 1 is the January 1, 1900. To convert between Sublight stardates and Excel serial dates, Subtract 2415018.5. (Julian dates are noon to noon.)

Humans are lazy, and will end up shortening that. This committee met in the late 19th century, and so the nearest rollover date in the past would be Julian Day 2400000 (Tue Nov 16, 1858). The next rollover day in the future will be 2500000 (Sun Aug 31, 2132). So it's standard practice to simply ditch the leading digits unless you are addressing dates well in the past, well into the future, or you happen to live in the years surrounding a rollover. And hope you aren't like the people in my second book who are on a ship that leaves Earth in 2490000 (2105-04-15) and won't get where they are going until 2510000 (2160-01-17).

Human Dates

While absolute dates are great for calculators, it's not very useful to people. No attempt is made to make metric years and months line up with Gregorian calendar years or months. They are just a way to break up absolute time into useful, user-friendly chunks.

To convert a stardate into an Excel serial date: DATE=(STARDATE-2415018.5)

A day is 24 hours long. A year is 364 days. The year is broken into 13 months of 28 days each. (13 * 28 = 364)

The names of the months are based on the Zodiac:

To calculate your Metric year:

int(floor(STARDATE/364))

This blog was posted in metric year: 6756

To calculate your Metric day of the year:

int(floor(STARDATE)) % 364

This blog was posted on the day of the year: 133

To calculate your Metric month:

(int(floor(STARDATE/28)) % 13)+1

This blog was posted on the month of : 5 (Taurus)

or

int(floor(DAY_OF_YEAR/28))+1

This blog was posted on the month of : 5 (Taurus)

To calculate the day of the month:

(int(floor(STARDATE)) % 28)+1}

This blog was posted on the day of: 22

or

(DAY_OR_YEAR % 28)+1

This blog was posted on the day of: 22

The days of the week are the traditional days, and the do line up with the days of the week back on Earth.

To calculate your Day of the week:

(int(STARDATE+1) % 7)+1

This blog was posted on a: 2 (Monday)

Example dates

proc FORMAT_DATE {STARDATE} {
  set YEAR 364
  set MONTH 28
  set MONTH_LIST {{} Capricorn Aquarius Pisces Aries Taurus Gemini Cancer Leo Virgo Libra Scorpio Sagittarius}
  set DAYS_OF_WEEK {{} Sunday Monday Tuesday Wednesday Thursday Friday Saturday}

  set year  [expr {int(floor($STARDATE/$YEAR))}]
  set monthidx [expr {(int(floor($STARDATE/$MONTH)) % 13)+1}]
  set month    [lindex $MONTH_LIST $monthidx]
  set dayweek [expr {(int($STARDATE+1) % 7)+1}]
  set dayofweek [lindex $DAYS_OF_WEEK $dayweek]
  set dom [expr {(int(floor($STARDATE)) % $MONTH)+1}]
  return "$dayofweek $month $dom, $year"
}

NOTE: All of the calculations for metric time use the full star date (2459317 VS 59317). You will get very different answers because 2400000 is not divisible by 364. Capricorn was chosen as the first month because, in the Zodiac, it is the constellation associated with the time of the Winter Solstice.

Calendar

Because every month is the same length, and every day of the year happens on the same day of the week, generating a calendar is very, very easy: