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:

Number Month Starts
1 Capricorn 1
2 Aquarius 29
3 Pisces 57
4 Aries 85
5 Taurus 113
6 Gemini 141
7 Cancer 169
8 Leo 197
9 Virgo 225
10 Libra 253
11 Scorpio 281
12 Ophiuchus 309
13 Sagittarius 337

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.

1 Sunday
2 Monday
3 Tuesday
4 Wednesday
5 Thursday
6 Friday
7 Saturday

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"
}

-1930000 9997 B.C. Saturday Scorpio 13, -5303 Oldest settlements in Damascus
918025 Thu Jun 01, 2200 B.C.E. Thursday Capricorn 18, 2522 Umm al Binni Crater formed
954550 Wed Jun 01, 2100 B.C.E. Wednesday Gemini 3, 2622 Epic of Gilgamesh Written
347724 Sun Jan 07, 3761 B.C.E. Sunday Aries 21, 955 Start of the Hebrew Calendar
1721424 Sat Jan 01, 0001 C.E. Saturday Pisces 13, 4729 Start of the Common Era (aka A.D.)
1720321 Tue Dec 25, 0004 B.C.E. Tuesday Pisces 2, 4726 Birth of Christ (Estimated)
2101070 Sun Jun 01, 1040 C.E. Sunday Pisces 7, 5772 Movable Type invented (China)
2400000 Tue Nov 16, 1858 C.E. Tuesday Gemini 9, 6593 Start of current epoch
2415386 Tue Jan 01, 1901 C.E. Tuesday Virgo 23, 6635 Turn of the 20th Century
2440423 Sun Jul 20, 1969 C.E. Sunday Gemini 28, 6704 Apollo 11 Touched down on the moon
2451911 Mon Jan 01, 2001 C.E. Monday Capricorn 8, 6736 Turn of the 21st Century
2459350 Sat May 15, 2021 C.E. Saturday Gemini 27, 6756 Page last Cached
2500000 Sun Aug 31, 2132 C.E. Sunday Aquarius 21, 6868 Start of next epoch
2536727 Fri Mar 22, 2233 C.E. Friday Capricorn 12, 6969 Birth of James T. Kirk

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:

Capricorn
Mon Tues Wed Thur Fri Sat Sun
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
11
12
12
13
13
14
14
15
15
16
16
17
17
18
18
19
19
20
20
21
21
22
22
23
23
24
24
25
25
26
26
27
27
28
28
Aquarius
Mon Tues Wed Thur Fri Sat Sun
1
29
2
30
3
31
4
32
5
33
6
34
7
35
8
36
9
37
10
38
11
39
12
40
13
41
14
42
15
43
16
44
17
45
18
46
19
47
20
48
21
49
22
50
23
51
24
52
25
53
26
54
27
55
28
56
Pisces
Mon Tues Wed Thur Fri Sat Sun
1
57
2
58
3
59
4
60
5
61
6
62
7
63
8
64
9
65
10
66
11
67
12
68
13
69
14
70
15
71
16
72
17
73
18
74
19
75
20
76
21
77
22
78
23
79
24
80
25
81
26
82
27
83
28
84
Aries
Mon Tues Wed Thur Fri Sat Sun
1
85
2
86
3
87
4
88
5
89
6
90
7
91
8
92
9
93
10
94
11
95
12
96
13
97
14
98
15
99
16
100
17
101
18
102
19
103
20
104
21
105
22
106
23
107
24
108
25
109
26
110
27
111
28
112
Taurus
Mon Tues Wed Thur Fri Sat Sun
1
113
2
114
3
115
4
116
5
117
6
118
7
119
8
120
9
121
10
122
11
123
12
124
13
125
14
126
15
127
16
128
17
129
18
130
19
131
20
132
21
133
22
134
23
135
24
136
25
137
26
138
27
139
28
140
Gemini
Mon Tues Wed Thur Fri Sat Sun
1
141
2
142
3
143
4
144
5
145
6
146
7
147
8
148
9
149
10
150
11
151
12
152
13
153
14
154
15
155
16
156
17
157
18
158
19
159
20
160
21
161
22
162
23
163
24
164
25
165
26
166
27
167
28
168
Cancer
Mon Tues Wed Thur Fri Sat Sun
1
169
2
170
3
171
4
172
5
173
6
174
7
175
8
176
9
177
10
178
11
179
12
180
13
181
14
182
15
183
16
184
17
185
18
186
19
187
20
188
21
189
22
190
23
191
24
192
25
193
26
194
27
195
28
196
Leo
Mon Tues Wed Thur Fri Sat Sun
1
197
2
198
3
199
4
200
5
201
6
202
7
203
8
204
9
205
10
206
11
207
12
208
13
209
14
210
15
211
16
212
17
213
18
214
19
215
20
216
21
217
22
218
23
219
24
220
25
221
26
222
27
223
28
224
Virgo
Mon Tues Wed Thur Fri Sat Sun
1
225
2
226
3
227
4
228
5
229
6
230
7
231
8
232
9
233
10
234
11
235
12
236
13
237
14
238
15
239
16
240
17
241
18
242
19
243
20
244
21
245
22
246
23
247
24
248
25
249
26
250
27
251
28
252
Libra
Mon Tues Wed Thur Fri Sat Sun
1
253
2
254
3
255
4
256
5
257
6
258
7
259
8
260
9
261
10
262
11
263
12
264
13
265
14
266
15
267
16
268
17
269
18
270
19
271
20
272
21
273
22
274
23
275
24
276
25
277
26
278
27
279
28
280
Scorpio
Mon Tues Wed Thur Fri Sat Sun
1
281
2
282
3
283
4
284
5
285
6
286
7
287
8
288
9
289
10
290
11
291
12
292
13
293
14
294
15
295
16
296
17
297
18
298
19
299
20
300
21
301
22
302
23
303
24
304
25
305
26
306
27
307
28
308
Ophiuchus
Mon Tues Wed Thur Fri Sat Sun
1
309
2
310
3
311
4
312
5
313
6
314
7
315
8
316
9
317
10
318
11
319
12
320
13
321
14
322
15
323
16
324
17
325
18
326
19
327
20
328
21
329
22
330
23
331
24
332
25
333
26
334
27
335
28
336
Sagittarius
Mon Tues Wed Thur Fri Sat Sun
1
337
2
338
3
339
4
340
5
341
6
342
7
343
8
344
9
345
10
346
11
347
12
348
13
349
14
350
15
351
16
352
17
353
18
354
19
355
20
356
21
357
22
358
23
359
24
360
25
361
26
362
27
363
28
364