Davidian Martian Calendar

The Davidian Martian Calendar is a proposed system of time-keeping designed to serve the needs of future human settlers on the planet Mars. It was established by David Powell in Gregorian Year 1988. In 1996, a system of converting dates between Gregorian and Davidian calendars was created.

Calendar Terms[]

The Davidian calendar uses the same terminology as that used by the Gregorian calendar:

Minute: Period of 60 Martian seconds (61.62s on Earth).

Hour: Period of 60 Martian minutes (61m 38.968s on Earth).

Day: Period of 24 Martian hours (24h 39m 35.244s on Earth).

Week: A period of 7 days, same as on Earth.

Month: A unit of time that on Mars simply means 1/12 of a year.

Year length and intercalation[]

The Martian year is 669.5907 Martian days long. Therefore, with very rare exceptions, every century must have 59 leap years. That means that unlike on Earth, leap years are actually more common than "common" years.

Leap years are as follows:

Every even numbered year except for those that end in "00"
Every odd-numbered year that is evenly divisible by 5.

Additionally, years that end in 0000, 2000, 4000, 5000, 6000, 8000, and 9000 begin with a January 0 or "Millennium Day" that does not belong to any day of the week.

Calendar Layout[]

The year is divided into 12 months. All months except for June and October have 56 days. February has 55 days during common years and 56 days during leap years. June and October have 55 days.

The days of the week are the same as the Gregorian calendar, with the exception of Tuesday, which has been replaced with Gaiaday. This is because Tuesday is named after Mars and it would be more appropriate to replace it on the Martian calendar with a day that is named after Earth.

January							February								March
Sun	Mon	Gai	Wed	Thu	Fri	Sat	Sun	Mon	Gai	Wed	Thu	Fri	Sat		Sun	Mon	Gai	Wed	Thu	Fri	Sat
1	2	3	4	5	6	7	1	2	3	4	5	6	7		1	2	3	4	5	6	7
8	9	10	11	12	13	14	8	9	10	11	12	13	14		8	9	10	11	12	13	14
15	16	17	18	19	20	21	15	16	17	18	19	20	21		15	16	17	18	19	20	21
22	23	24	25	26	27	28	22	23	24	25	26	27	28		22	23	24	25	26	27	28
29	30	31	32	33	34	35	29	30	31	32	33	34	35		29	30	31	32	33	34	35
36	37	38	39	40	41	42	36	37	38	39	40	41	42		36	37	38	39	40	41	42
43	44	45	46	47	48	49	43	44	45	46	47	48	49		43	44	45	46	47	48	49
50	51	52	53	54	55	56	50	51	52	53	54	55	56*		50	51	52	53	54	55	56

April							May									June
Sun	Mon	Gai	Wed	Thu	Fri	Sat	Sun	Mon	Gai	Wed	Thu	Fri	Sat	Sun		Mon	Gai	Wed	Thu	Fri	Sat
1	2	3	4	5	6	7	1	2	3	4	5	6	7	1		2	3	4	5	6	7
8	9	10	11	12	13	14	8	9	10	11	12	13	14	8		9	10	11	12	13	14
15	16	17	18	19	20	21	15	16	17	18	19	20	21	15		16	17	18	19	20	21
22	23	24	25	26	27	28	22	23	24	25	26	27	28	22		23	24	25	26	27	28
29	30	31	32	33	34	35	29	30	31	32	33	34	35	29		30	31	32	33	34	35
36	37	38	39	40	41	42	36	37	38	39	40	41	42	36		37	38	39	40	41	42
43	44	45	46	47	48	49	43	44	45	46	47	48	49	43		44	45	46	47	48	49
50	51	52	53	54	55	56	50	51	52	53	54	55	56	50		51	52	53	54	55

July							August								September
Sun	Mon	Gai	Wed	Thu	Fri	Sat	Sun	Mon	Gai	Wed	Thu	Fri	Sat		Sun	Mon	Gai	Wed	Thu	Fri	Sat
						1							1								1
2	3	4	5	6	7	8	2	3	4	5	6	7	8		2	3	4	5	6	7	8
9	10	11	12	13	14	15	9	10	11	12	13	14	15		9	10	11	12	13	14	15
16	17	18	19	20	21	22	16	17	18	19	20	21	22		16	17	18	19	20	21	22
23	24	25	26	27	28	29	23	24	25	26	27	28	29		23	24	25	26	27	28	29
30	31	32	33	34	35	36	30	31	32	33	34	35	36		30	31	32	33	34	35	36
37	38	39	40	41	42	43	37	38	39	40	41	42	43		37	38	39	40	41	42	43
44	45	46	47	48	49	50	44	45	46	47	48	49	50		44	45	46	47	48	49	50
51	52	53	54	55	56		51	52	53	54	55	56			51	52	53	54	55	56

October							November								December
Sun	Mon	Gai	Wed	Thu	Fri	Sat	Sun	Mon	Gai	Wed	Thu	Fri	Sat		Sun	Mon	Gai	Wed	Thu	Fri	Sat
						1						1	2							1	2
2	3	4	5	6	7	8	3	4	5	6	7	8	9		3	4	5	6	7	8	9
9	10	11	12	13	14	15	10	11	12	13	14	15	16		10	11	12	13	14	15	16
16	17	18	19	20	21	22	17	18	19	20	21	22	23		17	18	19	20	21	22	23
23	24	25	26	27	28	29	24	25	26	27	28	29	30		24	25	26	27	28	29	30
30	31	32	33	34	35	36	31	32	33	34	35	36	37		31	32	33	34	35	36	37
37	38	39	40	41	42	43	38	39	40	41	42	43	44		38	39	40	41	42	43	44
44	45	46	47	48	49	50	45	46	47	48	49	50	51		45	46	47	48	49	50	51
51	52	53	54	55			52	53	54	55	56				52	53	54	55	56

February 56th is an intercalary day that only occurs during leap years.

Epoch[]

To simplify the equation necessary to convert Gregorian dates to Martian dates, a common epoch is needed. Originally, the Gregorian epoch (January 1, 0001 CE) was used. However, it was later decided that the Davidian calendar would follow the same epoch as the Holocene calendar. This means that January 1, 0000 on the Davidian calendar is equivalent to January 1, 10001 BCE of the Gregorian calendar. This means that every date in recorded history is expressed in positive-numbered years.

Calendar dates use the suffix DM, to distinguish them from BCE/BC and CE/AD (Gregorian) and HE (Holocene). For dates that occurred before the epoch, negative numbers are used. For example, 20000 years before Year 0 would be expressed as -20000 DM.

Start of the year and Seasons[]

Because the Davidian epoch is based on a common January 1st between the Davidian and Holocene calendars, the beginning of the year is completely unrelated to seasons. In fact, Martian seasons begin in months that would be strange on Earth:

Date	Event (Northern Hemisphere)	Event (Southern Hemisphere)
January 35	Fall Equinox	Spring Equinox
April 10	Winter Solstice	Summer Solstice
June 51	Spring Equinox	Fall Equinox
October 22	Summer Solstice	Winter Solstice

Rationale[]

While other Martian calendars (notably the Darian calendar) incorporate very creative things like new names for months, days of the week, etc, the Davidian Calendar builds from what is already familiar to future settlers.

Conversion[]

The Davidian Calendar is unique among proposed Martian calendars in that it is designed to be converted back and forth between Davidian and Gregorian dates.

Gregorian to Davidian[]

The formula for converting Gregorian (Earth) dates to Davidian (Martian) dates:

( (ED + 10000) * 365.26) / 686.98

Where "ED" = Earth Date

For example:

July 20, 1969 (1969.5479) is equivalent to January 55, 6364 (6364.0820).

( (1969.5479 + 10000) X 365.26) / 686.98 = 6364.0820

Davidian to Gregorian[]

The formula for converting Davidian (Martian) dates to Gregorian (Earth) dates:

( (MD X 686.98) / 365.26) - 10000

Where "MD" = Martian Date

For example:

December 2, 6365 (6365.9178) is equivalent to January 1, 1973 (1973.0006)

( (6365.9178 X 686.98) / 365.26) - 10000 = 1973.0006

Historical Events[]

Major world historical events, shown in Davidian, Gregorian, and Holocene dates. Note: approximate "circa" dates are rounded and do not calculate directly.

Events	Davidian (Mars)	Gregorian (Earth)	Holocene (Earth)
End of the Paleolithic Period, All continents (except Antarctica) inhabited, Agriculture and the domestication of animals begins.	c. 0 DM	c. 10000 BCE	c. 0 HE
Earliest walled city (Jericho)	c. 530 DM	c. 9000 BCE	c. 1000 HE
First copper found in Middle East - beginning of Copper Age	c. 2100 DM	c. 6000 BCE	c. 4000
Beginning of Indus Valley Civilization	c. 3700	c. 3000 BCE	c. 7000
Probable date of the completion of the first Egyptian pyramid	3928	2611 BCE	7390
Moses leads the Hebrews out of Egypt	c. 4649	c. 1245 BCE	c. 8748
Foundation of Rome	4917	753 BCE	9248
Imperial China, Qin dynasty	5199	221 BCE	9780
Birth of Jesus Christ	5314	5 BCE	9996
Possible year of Jesus' crucifixion	5332	30 CE	10030
Fall of Rome	5569	476	10476
Muslim conquests begin	5652	632	10632
Black Death decimates Asia and Europe	6030s	1340s	11340s
European discovery of the New World	6110	1492	11492
The United States of America declares independence from Britain	June 18, 6261	July 4, 1776	July 4, 11776
French Revolution	May 24, 6268	July 14, 1789	July 14, 11789
American Civil War	6306-6308	1861-1865	11861-11865
World War I	6334-6336	1914-1918	11914-11918
World War II	6348-6351	1939-1945	11939-11945
First human landing on the Moon	January 55, 6364	July 20, 1969	July 20, 11969
Viking Landing on Mars	October 7, 6367	June 19, 1976	June 19, 11976
Pathfinder Landing on Mars	December 20, 6378	July 4, 1997	July 4, 11997
September 11 Terrorist Attacks	March 6, 6381	September 11, 2001	September 11, 12001
Current Year	6385	2010	12010

Holidays[]

Holidays present a dilemma in a multi-planetary civilization. Holidays that celebrate significant historical events will probably be celebrated once per Martian year on the same date each year. Holidays of religious significance, such as Christmas, Easter, Passover, and Ramadan will probably be celebrated when they occur on Earth, regardless of what the date happens to be on Mars. This means they will occur twice annually in varying months and seasons.

Holiday	Davidian (Mars)	Gregorian (Earth)
Ramadan 2010	Begins November 55, 6385	Begins August 11, 2010
Hanukkah 2010	January 53, 6386	December 2, 2010
Christmas 2010	February 20, 6386	December 25, 2010
Easter 2011	April 8, 6386*	April 4, 2011
Ramadan 2011	Begins June 9, 6386	Begins August 1, 2011
Hanukkah 2011	August 37, 6386	December 21, 2011
Christmas 2011	August 41, 6386	December 25, 2011
Easter 2012	October 30, 6386*	April 8, 2012

Easter on Mars presumably occurs on the Martian Sunday closest to the Earth Sunday it is observed on Earth, rather than on the actual calendar date.

External Links[]

http://akdave.wikia.com/wiki/Davidian_Martian_Calendar The Davidian Martian Calendar at the AKDave Wiki