A Calendar for Indigenous Martians

A discussion came up on the world build mailing list (my original mail) about time keeping on Mars. Most of the responses tried to stick our calendar onto Mars and tweak it. Since the designer had indigenous Martians who were not too technologically advanced it seemed more logical to use their astronomical observations to build a calendar. Hence the calendar should maintain some relation to the seasons on Mars and not be entirely artificial, yet have a few tweaks to make it more convenient for them to use. I've found several different sets of data for the length of the seasons so I used the ones that came closest to the calendar anyway.

Since Mars's moons aren't the big honkers ours is and revolve to fast to be useful I didn't use them for months. Instead the length of a month is based on the length of the orb - the 4 holidays and the martian length of the week 8 sol. This gives us a standard 32 sol month. By shifting the holidays a sol or two forward every month can start on the same sol name.

Ideally the Martians should have their own words for days, months and years. I used sol for a Martian day based on NASA use during the Viking missions. Mensis comes from Latin for month. Orb is short for orbit, I found it used on a Mars calendar page and like it better than the Latin annus for a year. Weekday names are similar to many Earth cultures using the "planets", including the Sun and both of Mar's moons in order of what I think would be their brightness in the sky.

Many orbs would have 669 sols. A few 668. Priests/Astronomers on Mars should determine each orb if the 669th sol is the Last sol of an orb or the First sol of a new one by observation and later calculation of the sunrise on that day. Martian culture would use this day culturally; if its the 669th sol celebrations as the gods make the orb longer or the opposite as the spring has been postponed.

Leap Years I'm still working on this part
After calculations each odd orb is 669 sols long. Each even 668. If the orb is divisible by 11 add an additional sol. If divisible by 750 add another. This cycle will gain almost 1 day every 10,000 orbs. Someone should invent an atomic clock by then. Leap orb calculation Yes it is possible to have leap orbs, 11 leap orbs and 750 leap orbs in the same orb.

2004-01-26: Actually its much easier than that there is a system to do 668/699 days all the time for thousands of years, the defaults for the calculation program show this now. I just havent updated this calendar.


Raw Data:

1 Sol = 1 rotation of Mars on its axis = 24.6229 Earth days
1 Orb = 1 revolution of Mars about the Sun
Number of sols in 1 orb: 668.5921 = 686.98 Earth days
1 revolution of Deimos around Mars: 30 earth hrs
1 revolution of Phobos around Mars: 7.6 earth hrs
Spring lasts 193.30 sols or 194 sols
Summer lasts 178.64 sols or 178 sols
Autumn lasts 142.70 sols or 142 sols
Winter lasts 153.94 sols or 154 sols

First Sol
Intercalary Sol
  • Sol 1
Vernal Equinox
Mensis 1-6
Sunsol Earthsol Venussol Jupitersol Satrunsol Phobossol Demiossol Mercurysol
1
  • Sol 2
  • Sol 34
  • Sol 66
  • Sol 98
  • Sol 130
  • Sol 162
2
  • Sol 3
  • Sol 35
  • Sol 67
  • Sol 99
  • Sol 131
  • Sol 163
3
  • Sol 4
  • Sol 36
  • Sol 68
  • Sol 100
  • Sol 132
  • Sol 164
4
  • Sol 5
  • Sol 37
  • Sol 69
  • Sol 101
  • Sol 133
  • Sol 165
5
  • Sol 6
  • Sol 38
  • Sol 70
  • Sol 102
  • Sol 134
  • Sol 166
6
  • Sol 7
  • Sol 39
  • Sol 71
  • Sol 103
  • Sol 135
  • Sol 167
7
  • Sol 8
  • Sol 40
  • Sol 72
  • Sol 104
  • Sol 136
  • Sol 168
8
  • Sol 9
  • Sol 41
  • Sol 73
  • Sol 105
  • Sol 137
  • Sol 169
9
  • Sol 10
  • Sol 42
  • Sol 74
  • Sol 106
  • Sol 138
  • Sol 170
10
  • Sol 11
  • Sol 43
  • Sol 75
  • Sol 107
  • Sol 139
  • Sol 171
11
  • Sol 12
  • Sol 44
  • Sol 76
  • Sol 108
  • Sol 140
  • Sol 172
12
  • Sol 13
  • Sol 45
  • Sol 77
  • Sol 109
  • Sol 141
  • Sol 173
13
  • Sol 14
  • Sol 46
  • Sol 78
  • Sol 110
  • Sol 142
  • Sol 174
14
  • Sol 15
  • Sol 47
  • Sol 79
  • Sol 111
  • Sol 143
  • Sol 175
15
  • Sol 16
  • Sol 48
  • Sol 80
  • Sol 112
  • Sol 144
  • Sol 176
16
  • Sol 17
  • Sol 49
  • Sol 81
  • Sol 113
  • Sol 145
  • Sol 177
17
  • Sol 18
  • Sol 50
  • Sol 82
  • Sol 114
  • Sol 146
  • Sol 178
18
  • Sol 19
  • Sol 51
  • Sol 83
  • Sol 115
  • Sol 147
  • Sol 179
19
  • Sol 20
  • Sol 52
  • Sol 84
  • Sol 116
  • Sol 148
  • Sol 180
20
  • Sol 21
  • Sol 53
  • Sol 85
  • Sol 117
  • Sol 149
  • Sol 181
21
  • Sol 22
  • Sol 54
  • Sol 86
  • Sol 118
  • Sol 150
  • Sol 182
22
  • Sol 23
  • Sol 55
  • Sol 87
  • Sol 119
  • Sol 151
  • Sol 183
23
  • Sol 24
  • Sol 56
  • Sol 88
  • Sol 120
  • Sol 152
  • Sol 184
24
  • Sol 25
  • Sol 57
  • Sol 89
  • Sol 121
  • Sol 153
  • Sol 185
25
  • Sol 26
  • Sol 58
  • Sol 90
  • Sol 122
  • Sol 154
  • Sol 186
26
  • Sol 27
  • Sol 59
  • Sol 91
  • Sol 123
  • Sol 155
  • Sol 187
27
  • Sol 28
  • Sol 60
  • Sol 92
  • Sol 124
  • Sol 156
  • Sol 188
28
  • Sol 29
  • Sol 61
  • Sol 93
  • Sol 125
  • Sol 157
  • Sol 189
29
  • Sol 30
  • Sol 62
  • Sol 94
  • Sol 126
  • Sol 158
  • Sol 190
30
  • Sol 31
  • Sol 63
  • Sol 95
  • Sol 127
  • Sol 159
  • Sol 191
31
  • Sol 32
  • Sol 64
  • Sol 96
  • Sol 128
  • Sol 160
  • Sol 192
32
  • Sol 33
  • Sol 65
  • Sol 97
  • Sol 129
  • Sol 161
  • Sol 193
Summer Sol
Intercalary Sol
  • Sol 194
Summer Solstice
Mensis 7-12
Sun Deimos Phobos Mercury Venus Earth Jupiter Saturn
1
  • Sol 195
  • Sol 227
  • Sol 259
  • Sol 291
  • Sol 323
2
  • Sol 196
  • Sol 228
  • Sol 260
  • Sol 292
  • Sol 324
3
  • Sol 197
  • Sol 229
  • Sol 261
  • Sol 293
  • Sol 325
4
  • Sol 198
  • Sol 230
  • Sol 262
  • Sol 294
  • Sol 326
5
  • Sol 199
  • Sol 231
  • Sol 263
  • Sol 295
  • Sol 327
6
  • Sol 200
  • Sol 232
  • Sol 264
  • Sol 296
  • Sol 328
7
  • Sol 201
  • Sol 233
  • Sol 265
  • Sol 297
  • Sol 329
8
  • Sol 202
  • Sol 234
  • Sol 266
  • Sol 298
  • Sol 330
9
  • Sol 203
  • Sol 235
  • Sol 267
  • Sol 299
  • Sol 331
10
  • Sol 204
  • Sol 236
  • Sol 268
  • Sol 300
  • Sol 332
11
  • Sol 205
  • Sol 237
  • Sol 269
  • Sol 301
  • Sol 333
12
  • Sol 206
  • Sol 238
  • Sol 270
  • Sol 302
  • Sol 334
13
  • Sol 207
  • Sol 239
  • Sol 271
  • Sol 303
  • Sol 335
14
  • Sol 208
  • Sol 240
  • Sol 272
  • Sol 304
  • Sol 336
15
  • Sol 209
  • Sol 241
  • Sol 273
  • Sol 305
  • Sol 337
16
  • Sol 210
  • Sol 242
  • Sol 274
  • Sol 306
  • Sol 338
17
  • Sol 211
  • Sol 243
  • Sol 275
  • Sol 307
  • Sol 339
18
  • Sol 212
  • Sol 244
  • Sol 276
  • Sol 308
  • Sol 340
19
  • Sol 213
  • Sol 245
  • Sol 277
  • Sol 309
  • Sol 341
20
  • Sol 214
  • Sol 246
  • Sol 278
  • Sol 310
  • Sol 342
21
  • Sol 215
  • Sol 247
  • Sol 279
  • Sol 311
  • Sol 343
22
  • Sol 216
  • Sol 248
  • Sol 280
  • Sol 312
  • Sol 344
23
  • Sol 217
  • Sol 249
  • Sol 281
  • Sol 313
  • Sol 345
24
  • Sol 218
  • Sol 250
  • Sol 282
  • Sol 314
  • Sol 346
25
  • Sol 219
  • Sol 251
  • Sol 283
  • Sol 315
  • Sol 347
26
  • Sol 220
  • Sol 252
  • Sol 284
  • Sol 316
  • Sol 348
27
  • Sol 221
  • Sol 253
  • Sol 285
  • Sol 317
  • Sol 349
28
  • Sol 222
  • Sol 254
  • Sol 286
  • Sol 318
  • Sol 350
29
  • Sol 223
  • Sol 255
  • Sol 287
  • Sol 319
  • Sol 351
30
  • Sol 224
  • Sol 256
  • Sol 288
  • Sol 320
  • Sol 352
31
  • Sol 225
  • Sol 257
  • Sol 289
  • Sol 321
  • Sol 353
32
  • Sol 226
  • Sol 258
  • Sol 290
  • Sol 322
  • Sol 354
Mensis 13
Sun Deimos Phobos Mercury Venus Earth Jupiter Saturn
1
  • Sol 355
2
  • Sol 356
3
  • Sol 357
4
  • Sol 358
5
  • Sol 359
6
  • Sol 360
7
  • Sol 361
8
  • Sol 362
9
  • Sol 363
10
  • Sol 364
11
  • Sol 365
12
  • Sol 366
13
  • Sol 367
14
  • Sol 368
15
  • Sol 369
16
  • Sol 370
Autumnal Sol
Intercalary Sol
  • Sol 371
Autumnal Equinox
Mensis 14-18
Sun Deimos Phobos Mercury Venus Earth Jupiter Saturn
1
  • Sol 372
  • Sol 404
  • Sol 436
  • Sol 468
2
  • Sol 373
  • Sol 405
  • Sol 437
  • Sol 469
3
  • Sol 374
  • Sol 406
  • Sol 438
  • Sol 470
4
  • Sol 375
  • Sol 407
  • Sol 439
  • Sol 471
5
  • Sol 376
  • Sol 408
  • Sol 440
  • Sol 472
6
  • Sol 377
  • Sol 409
  • Sol 441
  • Sol 473
7
  • Sol 378
  • Sol 410
  • Sol 442
  • Sol 474
8
  • Sol 379
  • Sol 411
  • Sol 443
  • Sol 475
9
  • Sol 380
  • Sol 412
  • Sol 444
  • Sol 476
10
  • Sol 381
  • Sol 413
  • Sol 445
  • Sol 477
11
  • Sol 382
  • Sol 414
  • Sol 446
  • Sol 478
12
  • Sol 383
  • Sol 415
  • Sol 447
  • Sol 479
13
  • Sol 384
  • Sol 416
  • Sol 448
  • Sol 480
14
  • Sol 385
  • Sol 417
  • Sol 449
  • Sol 481
15
  • Sol 386
  • Sol 418
  • Sol 450
  • Sol 482
16
  • Sol 387
  • Sol 419
  • Sol 451
  • Sol 483
17
  • Sol 388
  • Sol 420
  • Sol 452
  • Sol 484
18
  • Sol 389
  • Sol 421
  • Sol 453
  • Sol 485
19
  • Sol 390
  • Sol 422
  • Sol 454
  • Sol 486
20
  • Sol 391
  • Sol 423
  • Sol 455
  • Sol 487
21
  • Sol 392
  • Sol 424
  • Sol 456
  • Sol 488
22
  • Sol 393
  • Sol 425
  • Sol 457
  • Sol 489
23
  • Sol 394
  • Sol 426
  • Sol 458
  • Sol 490
24
  • Sol 395
  • Sol 427
  • Sol 459
  • Sol 491
25
  • Sol 396
  • Sol 428
  • Sol 460
  • Sol 492
26
  • Sol 397
  • Sol 429
  • Sol 461
  • Sol 493
27
  • Sol 398
  • Sol 430
  • Sol 462
  • Sol 494
28
  • Sol 399
  • Sol 431
  • Sol 463
  • Sol 495
29
  • Sol 400
  • Sol 432
  • Sol 464
  • Sol 496
30
  • Sol 401
  • Sol 433
  • Sol 465
  • Sol 497
31
  • Sol 402
  • Sol 434
  • Sol 466
  • Sol 498
32
  • Sol 403
  • Sol 435
  • Sol 467
  • Sol 499
Mensis 19
Sun Deimos Phobos Mercury Venus Earth Jupiter Saturn
1
  • Sol 500
2
  • Sol 501
3
  • Sol 502
4
  • Sol 503
5
  • Sol 504
6
  • Sol 505
7
  • Sol 506
8
  • Sol 507
9
  • Sol 508
10
  • Sol 509
11
  • Sol 510
12
  • Sol 511
13
  • Sol 512
14
  • Sol 513
15
  • Sol 514
16
  • Sol 515
Winter Sol
Intercalary Sol
  • Sol 516
2 days after Winter Solstice
Mensis 20-24
Sun Deimos Phobos Mercury Venus Earth Jupiter Saturn
1
  • Sol 517
  • Sol 549
  • Sol 581
  • Sol 613
2
  • Sol 518
  • Sol 550
  • Sol 582
  • Sol 614
3
  • Sol 519
  • Sol 551
  • Sol 583
  • Sol 615
4
  • Sol 520
  • Sol 552
  • Sol 584
  • Sol 616
5
  • Sol 521
  • Sol 553
  • Sol 585
  • Sol 617
6
  • Sol 522
  • Sol 554
  • Sol 586
  • Sol 618
7
  • Sol 523
  • Sol 555
  • Sol 587
  • Sol 619
8
  • Sol 524
  • Sol 556
  • Sol 588
  • Sol 620
9
  • Sol 525
  • Sol 557
  • Sol 589
  • Sol 621
10
  • Sol 526
  • Sol 558
  • Sol 590
  • Sol 622
11
  • Sol 527
  • Sol 559
  • Sol 591
  • Sol 623
12
  • Sol 528
  • Sol 560
  • Sol 592
  • Sol 624
13
  • Sol 529
  • Sol 561
  • Sol 593
  • Sol 625
14
  • Sol 530
  • Sol 562
  • Sol 594
  • Sol 626
15
  • Sol 531
  • Sol 563
  • Sol 595
  • Sol 627
16
  • Sol 532
  • Sol 564
  • Sol 596
  • Sol 628
17
  • Sol 533
  • Sol 565
  • Sol 597
  • Sol 629
18
  • Sol 534
  • Sol 566
  • Sol 598
  • Sol 630
19
  • Sol 535
  • Sol 567
  • Sol 599
  • Sol 631
20
  • Sol 536
  • Sol 568
  • Sol 600
  • Sol 632
21
  • Sol 537
  • Sol 569
  • Sol 601
  • Sol 633
22
  • Sol 538
  • Sol 570
  • Sol 602
  • Sol 634
23
  • Sol 539
  • Sol 571
  • Sol 603
  • Sol 635
24
  • Sol 540
  • Sol 572
  • Sol 604
  • Sol 636
25
  • Sol 541
  • Sol 573
  • Sol 605
  • Sol 637
26
  • Sol 542
  • Sol 574
  • Sol 606
  • Sol 638
27
  • Sol 543
  • Sol 575
  • Sol 607
  • Sol 639
28
  • Sol 544
  • Sol 576
  • Sol 608
  • Sol 640
29
  • Sol 545
  • Sol 577
  • Sol 609
  • Sol 641
30
  • Sol 546
  • Sol 578
  • Sol 610
  • Sol 642
31
  • Sol 547
  • Sol 579
  • Sol 611
  • Sol 643
32
  • Sol 548
  • Sol 580
  • Sol 612
  • Sol 644
Mensis 25
Sun Deimos Phobos Mercury Venus Earth Jupiter Saturn
1
  • Sol 645
2
  • Sol 646
3
  • Sol 647
4
  • Sol 648
5
  • Sol 649
6
  • Sol 650
7
  • Sol 651
8
  • Sol 652
9
  • Sol 653
10
  • Sol 654
11
  • Sol 655
12
  • Sol 656
13
  • Sol 657
14
  • Sol 658
15
  • Sol 659
16
  • Sol 660
17
  • Sol 661
18
  • Sol 662
19
  • Sol 663
20
  • Sol 664
21
  • Sol 665
22
  • Sol 666
23
  • Sol 667
24
  • Sol 668
Leap Sol
Intercalary Sol
  • Sol 669
Only occurs in odd numbered orbs
11 Orb Leap Sol
Intercalary Sol
  • Sol 669 or 670
Only occurs in orbs divisible by 11
750 Orb Leap Sol
Intercalary Sol
  • Sol 669 or 670 or 671
Only occurs in orbs divisible by 750


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