A month approximates the moon's synodic orbital period. A common month comprises 29 or 30 days, depending on the type of year and its position within the year. Every so often, a leap month is inserted at the end of the year, named Aurora, which has 30 days. The average length of a month across a whole cycle is ≈29.5306 days.
| Year Length | Month Length | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | |
| 354 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | 29 | - |
| 355 | 30 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | - |
| 384 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | 29 | 30 | 29 | 30 |
Take the cycle index (which is the year number mod 1021, explained later), and look up which type it is in the appendix.
A year may contain 12 or 13 months, and total 354 (44%), 355 (19%), or 384 days (37%).
A year approximates Earth's tropical orbital period. A MLSC year is approximately ≈365.2419 days long, on average.
There is some predictability to the length of a year. A long leap year (384 days) can only be followed by a common year (354 days). A short leap year (355 days) can only be followed by a long leap year or a common year. Two common years are always followed by a long leap year. A short month is always followed by a long month, and two long months are always followed by a short month.
Knowing the current and previous year is helpful in predicting the following year:
| Last year | This year | Next year |
|---|---|---|
| 354 or 355 | 354 | 384 |
| 384 | 354 | any |
| any | 355 | 354 or 384 |
| any | 384 | 354 |
Additionally, knowing the current index of the metonic cycle (the cycle index mod 19) can sometimes tell you the year length:
| Metonic cycle index | Year length |
|---|---|
| 1, 12 | 384 |
| 2, 13 | 354 |
A cycle comprises 1021 years. The length of the cycle was chosen because the number of lunar synodic months in 1021 tropical years is quite nearly a whole number, simplifying calculations. A precession comprises 25 cycles (and is thus 25,525 MLSC years or about 25,524 Julian years). The current cycle in the precession determines the age. A precession approximates Earth's axial precession, and thus what constellation the vernal equinox lies in. Ages range from 1-3 cycles as described below:
| Age | Length (cycles) |
|---|---|
| Aries | 2 |
| Pisces | 3 |
| Aquarius | 2 |
| Capricornus | 2 |
| Sagittarius | 2 |
| Ophiuchus | 2 |
| Libra | 2 |
| Virgo | 3 |
| Leo | 2 |
| Cancer | 1 |
| Gemini | 2 |
| Taurus | 2 |
The age determines the name of the starting month. It's cosmetic, and does not affect any ordinal numbers.
Precessions start with Aries and proceed backwards around the zodiac. The current Age of Pisces began , and will end .
The largest division of time is the gal. A gal is 8,800 precessions (and is thus 224,620,000 MLSC years or about 224,615,031 Julian years). A gal approximates the time taken for the sun to orbit the milky way once (the galactic year). The current precession's beginning of the age of Aries defines the start of gal 0. The solar system therefore formed in gal -20, and the universe in gal -61.
| Unit | Length | (SI) |
|---|---|---|
| Day | 86,400 s | 8.64 × 104 s |
| Month | 29-30 d | ~2.6 × 106 s |
| Year | 12-13 mo 354-384 d |
~3.2 × 107 s |
| Cycle | 1,021 yr 12,628 mo 372,912 d |
3.22195968 × 1010 s |
| Age | 2-3 Cycles 2,042-3,063 yr |
~7 × 1010 s |
| Precession | 12 Ages 25 cycles 25,525 yr |
8.0548992 × 1011 s |
| Gal | 8,800 precessions 224.62 Myr |
7.088311296 × 1015 s |
The epoch, or fixed, defined point in time for the calendar, is , defined as being the start of the third cycle of the age of Pisces, first precession in the 61st gal.
This was chosen due to being the closest alignment of a new moon with the vernal equinox since 1583. At an error of just 62 minutes, no better alignment will occur in the 21st century. As an added bonus, the vernal equinox on this year occurs only 17 seconds after midnight UTC.
The following information is not necessary to understand the calendar, but instead gives enhanced vocabulary to describe it.
The kalends are the first day of the month (roughly a new moon). The nones are the eighth day of the month (roughly a first quarter moon). The ides are the sixteenth day of the month (roughly a full moon). The icas is the twenty-third day of the month (roughly a third quarter moon). The terms kalends, nones, and ides are pluralia tantum, but icas is a normal countable noun.
The days following one of these dates are given the following names:
| Days after | Name | Kal. | Non. | Eid. | Ica. |
|---|---|---|---|---|---|
| 0 | - | 1st | 8th | 16th | 23rd |
| 1 | Sol’s Day | 2nd | 9th | 17th | 24th |
| 2 | Luna’s Day | 3rd | 10th | 18th | 25th |
| 3 | Mars’s Day | 4th | 12th | 19th | 26th |
| 4 | Mercury’s Day | 5th | 13th | 20th | 27th |
| 5 | Jupiter’s Day | 6th | 13th | 21st | 28th |
| 6 | Venus’s Day | 7th | 14th | 22nd | 29th |
| 7 | Saturn’s Day | - | 15th | - | 30th |
These could be treated as weekdays, if one wished. The length of a "week" would then be 7 or 8 days, and of the pattern 7-8-7-7 (47%) or 7-8-7-8 (53%). This also means Saturn’s Day is the least probable day of the week, occuring only about 6% of the time, compared to about 16% for the other days.
Convenient side effects of this calendar include:
A watch is a period of two hours, centered on even hours during the day. The names of watches are the same as the month names, and are in the same order. However, the starting watch of the day is dependent on the age and month.
The concept of a watch is based on what zodiacal constellation (approximately) appears in the east at a given time. Because of this, the starting watch is defined such that the third watch (ie., the one from 5 AM to 7 AM) of the first month of the year (ie., the one typically the vernal equinox) is the same as the current age. For example, in the month of Pisces during the age of Pisces, the third watch is Pisces’ watch.
Therefore, the first watch (ie., the one from 1 AM to 3 AM) is equivalent to month + watch - age
(possibly offset by some constant, depending on how you define the start of the zodiacal cycle).
For example, in the month of Ophiuchus during the age of Pisces, the ninth watch (5 PM to 7 PM) is Taurus’s watch.
Common year (354-day) indices: 0, 2, 5, 7, 10, 13, 14, 16, 18, 21, 24, 26, 29, 30, 32, 35, 37, 40, 42, 44, 46, 48, 51, 53, 56, 57, 59, 62, 64, 67, 70, 72, 75, 76, 78, 81, 83, 86, 87, 89, 92, 94, 97, 99, 101, 103, 105, 108, 110, 113, 116, 117, 119, 121, 124, 127, 129, 132, 133, 135, 138, 140, 143, 144, 146, 149, 151, 154, 156, 159, 160, 162, 165, 167, 170, 173, 174, 176, 178, 181, 184, 186, 188, 190, 192, 195, 197, 200, 201, 203, 206, 208, 211, 213, 216, 219, 220, 222, 225, 227, 230, 231, 233, 236, 238, 241, 243, 246, 247, 249, 252, 254, 257, 260, 261, 263, 265, 268, 271, 273, 276, 277, 279, 282, 284, 287, 288, 290, 293, 295, 298, 300, 303, 304, 306, 309, 311, 314, 317, 318, 320, 322, 325, 328, 330, 333, 334, 336, 339, 341, 344, 345, 347, 350, 352, 355, 357, 360, 361, 363, 366, 368, 371, 374, 375, 377, 379, 382, 385, 387, 390, 391, 393, 396, 398, 401, 403, 405, 407, 409, 412, 414, 417, 420, 421, 423, 426, 428, 431, 432, 434, 437, 439, 442, 444, 447, 448, 450, 453, 455, 458, 461, 462, 464, 466, 469, 472, 474, 477, 478, 480, 483, 485, 488, 490, 492, 494, 496, 499, 501, 504, 505, 507, 510, 512, 515, 518, 519, 521, 523, 526, 529, 531, 534, 535, 537, 540, 542, 545, 547, 549, 551, 553, 556, 558, 561, 564, 565, 567, 569, 572, 575, 577, 579, 581, 583, 586, 588, 591, 592, 594, 597, 599, 602, 604, 606, 608, 610, 613, 615, 618, 621, 622, 624, 626, 629, 632, 634, 636, 638, 640, 643, 645, 648, 649, 651, 654, 656, 659, 662, 664, 667, 668, 670, 673, 675, 678, 679, 681, 684, 686, 689, 691, 693, 695, 697, 700, 702, 705, 708, 709, 711, 713, 716, 719, 721, 724, 725, 727, 730, 732, 735, 736, 738, 741, 743, 746, 748, 751, 752, 754, 757, 759, 762, 765, 766, 768, 770, 773, 776, 778, 781, 782, 784, 787, 789, 792, 793, 795, 798, 800, 803, 805, 808, 809, 811, 814, 816, 819, 822, 823, 825, 827, 830, 833, 835, 838, 839, 841, 844, 846, 849, 850, 852, 855, 857, 860, 863, 865, 868, 869, 871, 874, 876, 879, 880, 882, 885, 887, 890, 892, 895, 896, 898, 901, 903, 906, 909, 910, 912, 914, 917, 920, 922, 925, 926, 928, 931, 933, 936, 937, 939, 942, 944, 947, 949, 952, 953, 955, 958, 960, 963, 966, 967, 969, 971, 974, 977, 979, 982, 983, 985, 988, 990, 993, 995, 997, 999, 1001, 1004, 1006, 1009, 1012, 1013, 1015, 1017, 1020
Short leap (355-day) indices: 3, 8, 11, 19, 22, 27, 33, 38, 43, 49, 54, 60, 65, 68, 73, 79, 84, 90, 95, 100, 106, 111, 114, 122, 125, 130, 136, 141, 147, 152, 157, 163, 168, 171, 179, 182, 187, 193, 198, 204, 209, 214, 217, 223, 228, 234, 239, 244, 250, 255, 258, 266, 269, 274, 280, 285, 291, 296, 301, 307, 312, 315, 323, 326, 331, 337, 342, 348, 353, 358, 364, 369, 372, 380, 383, 388, 394, 399, 404, 410, 415, 418, 424, 429, 435, 440, 445, 451, 456, 459, 467, 470, 475, 481, 486, 491, 497, 502, 508, 513, 516, 524, 527, 532, 538, 543, 548, 554, 559, 562, 570, 573, 578, 584, 589, 595, 600, 605, 611, 616, 619, 627, 630, 635, 641, 646, 652, 657, 660, 665, 671, 676, 682, 687, 692, 698, 703, 706, 714, 717, 722, 728, 733, 739, 744, 749, 755, 760, 763, 771, 774, 779, 785, 790, 796, 801, 806, 812, 817, 820, 828, 831, 836, 842, 847, 853, 858, 861, 866, 872, 877, 883, 888, 893, 899, 904, 907, 915, 918, 923, 929, 934, 940, 945, 950, 956, 961, 964, 972, 975, 980, 986, 991, 996, 1002, 1007, 1010, 1018
Long leap (384-day) indices: 1, 4, 6, 9, 12, 15, 17, 20, 23, 25, 28, 31, 34, 36, 39, 41, 45, 47, 50, 52, 55, 58, 61, 63, 66, 69, 71, 74, 77, 80, 82, 85, 88, 91, 93, 96, 98, 102, 104, 107, 109, 112, 115, 118, 120, 123, 126, 128, 131, 134, 137, 139, 142, 145, 148, 150, 153, 155, 158, 161, 164, 166, 169, 172, 175, 177, 180, 183, 185, 189, 191, 194, 196, 199, 202, 205, 207, 210, 212, 215, 218, 221, 224, 226, 229, 232, 235, 237, 240, 242, 245, 248, 251, 253, 256, 259, 262, 264, 267, 270, 272, 275, 278, 281, 283, 286, 289, 292, 294, 297, 299, 302, 305, 308, 310, 313, 316, 319, 321, 324, 327, 329, 332, 335, 338, 340, 343, 346, 349, 351, 354, 356, 359, 362, 365, 367, 370, 373, 376, 378, 381, 384, 386, 389, 392, 395, 397, 400, 402, 406, 408, 411, 413, 416, 419, 422, 425, 427, 430, 433, 436, 438, 441, 443, 446, 449, 452, 454, 457, 460, 463, 465, 468, 471, 473, 476, 479, 482, 484, 487, 489, 493, 495, 498, 500, 503, 506, 509, 511, 514, 517, 520, 522, 525, 528, 530, 533, 536, 539, 541, 544, 546, 550, 552, 555, 557, 560, 563, 566, 568, 571, 574, 576, 580, 582, 585, 587, 590, 593, 596, 598, 601, 603, 607, 609, 612, 614, 617, 620, 623, 625, 628, 631, 633, 637, 639, 642, 644, 647, 650, 653, 655, 658, 661, 663, 666, 669, 672, 674, 677, 680, 683, 685, 688, 690, 694, 696, 699, 701, 704, 707, 710, 712, 715, 718, 720, 723, 726, 729, 731, 734, 737, 740, 742, 745, 747, 750, 753, 756, 758, 761, 764, 767, 769, 772, 775, 777, 780, 783, 786, 788, 791, 794, 797, 799, 802, 804, 807, 810, 813, 815, 818, 821, 824, 826, 829, 832, 834, 837, 840, 843, 845, 848, 851, 854, 856, 859, 862, 864, 867, 870, 873, 875, 878, 881, 884, 886, 889, 891, 894, 897, 900, 902, 905, 908, 911, 913, 916, 919, 921, 924, 927, 930, 932, 935, 938, 941, 943, 946, 948, 951, 954, 957, 959, 962, 965, 968, 970, 973, 976, 978, 981, 984, 987, 989, 992, 994, 998, 1000, 1003, 1005, 1008, 1011, 1014, 1016, 1019