The
Darian Calendar is a proposed system of time-keeping designed to serve the needs of any possible future
human settlersA manned mission to Mars has not taken place but is the subject of science fiction, engineering, and scientific proposals and plans throughout the 20th Century and into the 21st Century...
on the planet
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
. It was created by
aerospace engineerAerospace engineering is the branch of engineering behind the design, construction and science of aircraft and spacecraft. It is broken into two major and overlapping branches: aeronautical engineering and astronautical engineering...
and
political scientistPolitical science is a social science concerned with the theory and practice of politics and the description and analysis of political systems and political behavior. It is often described as the pragmatic application of the art and science of politics defined as "who gets what, when and how",...
Thomas Gangale in 1985 and named by him after his son
DariusThe boy's name Darius \d-rius\ is pronounced da-RYE-us, DARE-ee-us. Etymologically it is an Iranian word with Greek s, and its meaning is "he possesses; rich, kingly"....
.
The basic time periods from which the calendar is constructed are the Martian solar day (sometimes called a
solVarious schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars.Mars has an axial tilt and a rotation period similar to those of Earth. Thus it experiences seasons of spring, summer, autumn and winter much like Earth, and its...
) and the Martian vernal equinox year, which is slightly different from the
tropical yearA tropical year is the length of time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice.A tropical year can equivalently be defined as the time taken...
.
The
Darian Calendar is a proposed system of time-keeping designed to serve the needs of any possible future
human settlersA manned mission to Mars has not taken place but is the subject of science fiction, engineering, and scientific proposals and plans throughout the 20th Century and into the 21st Century...
on the planet
MarsMars is the fourth planet from the Sun in the Solar System. The planet is named after Mars, the Roman god of war. It is also referred to as the "Red Planet" because of its reddish appearance, due to iron oxide prevalent on its surface....
. It was created by
aerospace engineerAerospace engineering is the branch of engineering behind the design, construction and science of aircraft and spacecraft. It is broken into two major and overlapping branches: aeronautical engineering and astronautical engineering...
and
political scientistPolitical science is a social science concerned with the theory and practice of politics and the description and analysis of political systems and political behavior. It is often described as the pragmatic application of the art and science of politics defined as "who gets what, when and how",...
Thomas Gangale in 1985 and named by him after his son
DariusThe boy's name Darius \d-rius\ is pronounced da-RYE-us, DARE-ee-us. Etymologically it is an Iranian word with Greek s, and its meaning is "he possesses; rich, kingly"....
.
Year length and intercalation
The basic time periods from which the calendar is constructed are the Martian solar day (sometimes called a
solVarious schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars.Mars has an axial tilt and a rotation period similar to those of Earth. Thus it experiences seasons of spring, summer, autumn and winter much like Earth, and its...
) and the Martian vernal equinox year, which is slightly different from the
tropical yearA tropical year is the length of time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice.A tropical year can equivalently be defined as the time taken...
. The sol is 39 minutes 35.244 seconds longer than the Terrestrial solar day and the Martian vernal equinox year is 668.5907 sols in length. The basic
intercalationIntercalation is the insertion of a leap day, week or month into some calendar years to make the calendar follow the seasons or moon phases. Lunisolar calendars may require intercalations of both days and months....
formula therefore allocates six 669-sol years and four 668-sol years to each Martian decade. The former (still called
leap yearsLeap Years is a 2001 drama television series that aired on the Showtime cable network. The show was created by Ron Cowen and Daniel Lipman, who had created the American version of the series Queer as Folk. It followed a group of friends in New York City...
even though they are more common than non-leap years) are years that are either odd (not evenly divisible by 2) or else are evenly divisible by 10. The calendar error from the actual seasons is small, but the calendar is too slow by about 13 sols every 1400 Martian tropical years.
Calendar layout
The year is divided into 24
monthThe month is a unit of time, used with calendars, which is approximately as long as some natural period related to the motion of the Moon; month and Moon are cognates. The traditional concept arose with the cycle of moon phases; such months are synodic months and last approximately 29.53 days...
s. The first 5 months in each quarter have 28 sols. The final month has only 27 sols unless it is the final month of a leap year when it contains the leap sol as its final sol.
The calendar maintains a seven-sol
weekA week is a time unit equal to a number of days, now usually seven days. Weeks of between 4 and 20 days have been used historically in various places.-Four-day:The Igbo of Nigeria have a traditional calendar with a 4 day week...
, but the week is restarted from its first sol at the start of each month. If a month has 27 sols, this causes the final sol of the week to be omitted. This is partly for tidiness. It can also be rationalised as making the average length of the Martian week close to the average length of the Terrestrial week, although it must be remembered that 28 Earth days is roughly equal to 27+1/4 Martian sols and not 27+5/6 Martian sols.
In the following table, the days of the week are Sol Solis, Sol Lunae, Sol Martius, Sol Mercurii, Sol Jovis, Sol Veneris, Sol Saturni.
| Sagittarius |
|
Dhanus |
|
Capricornus |
| So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
| 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 |
| |
|
|
|
|
| Makara |
|
Aquarius |
|
Kumbha |
| So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
| 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 |
|
| |
|
|
|
|
| Pisces |
|
Mina |
|
Aries |
| So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
| 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 |
| |
|
|
|
|
| Mesha |
|
Taurus |
|
Rishabha |
| So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
| 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 |
|
| |
|
|
|
|
| Gemini |
|
Mithuna |
|
Cancer |
| So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
| 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 |
| |
|
|
|
|
| Karka |
|
Leo |
|
Simha |
| So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
| 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 |
|
| |
|
|
|
|
| Virgo |
|
Kanya |
|
Libra |
| So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
| 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 |
| |
|
|
|
|
| Tula |
|
Scorpius |
|
Vrishika |
| So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
So |
Lu |
Ma |
Me |
Jo |
Ve |
Sa |
| 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 |
The last day of Vrishika is an intercalary day that does not occur in every year.
Start of year
The Martian year is treated as beginning near the
equinoxAn equinox occurs twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, the Sun being vertically above a point on the Equator...
marking spring in the northern hemisphere of the planet. Mars currently has an
axial inclinationIn astronomy, axial tilt is the angle between an object's rotational axis and a line perpendicular to its orbital plane. The angle is measured between the line perpendicular to object's orbital plane and object's rotational axis passing through north pole at which the planet appears to rotate...
similar to that of the
EarthEarth is the third planet from the Sun. It is the fifth largest of the eight planets in the solar system, and the largest of the terrestrial planets in the Solar System in terms of diameter, mass and density...
, so the Martian seasons are perceptible, though the greater eccentricity of Mars' orbit about the
SunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
compared with that of the Earth means that their significance is strongly amplified in the southern hemisphere and masked in the northern hemisphere. The most sophisticated calculations of the Darian calendar extend to the point of making allowance for the slight increase in the length of the Martian vernal equinox year over several thousand years. These prescribe a more complicated intercalation formula (for details see the link cited below).
Epoch
Gangale originally chose late 1975 as the
epochIn the fields of chronology and periodization, an epoch means an instant in time chosen as the origin of a particular era. The "epoch" then serves as a reference point from which time is measured...
of the calendar in recognition of the
AmericanThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
Viking programNASA's Viking program consisted of a pair of space probes sent to Mars, Viking 1 and Viking 2. Each vehicle was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface...
as the first fully successful soft landing mission to Mars. In 2002 he adopted the Telescopic Epoch, first suggested by Peter Kokh, which is in 1609 in recognition of
Johannes KeplerIn astronomy, Kepler's three laws of planetary motion are:#The orbit of every planet is an ellipse with the sun at a focus.#A line joining a planet and the sun sweeps out equal areas during equal intervals of time....
's use of
Tycho BraheTycho Brahe, born Tyge Ottesen Brahe , was a Danish nobleman known for his accurate and comprehensive astronomical and planetary observations...
's observations of Mars to elucidate the laws of planetary motion, and also
Galileo GalileiGalileo Galilei was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations, and support for Copernicanism...
's first observations of Mars with a
telescopeA telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. The first known practically functioning telescopes were invented in the Netherlands at the beginning of the 17th century...
. Selection of the Telescopic Epoch avoids the problem of the many telescopic observations of Mars over the past 400 years being relegated to negative dates.
Nomenclature
Suggested variations of the Darian calendar abound on the World Wide Web that use different nomenclature schemata for the days of the week and the months of the year. The names of the 24 months were provisionally chosen by Gangale as the
LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. Through the Roman conquest, Latin spread throughout the Mediterranean and a large part of Europe...
names of
constellationIn modern astronomy, a constellation is an area of the celestial sphere, defined by exact boundaries.The term "constellation" can also be used loosely to refer to just the more prominent visible stars that seem to form a pattern in that area.-Definitions:...
s of the
zodiacIn astronomy, the zodiac is the ring of constellations that lines the ecliptic, which is the apparent path of the Sun across the sky over the course of the year. The Moon and planets also lie within the ecliptic, and so are also within the constellations of the zodiac. In astrology, the zodiac...
and their
SanskritSanskrit is a historical Indo-Aryan language, one of the liturgical languages of Hinduism and Buddhism, and one of the 22 official languages of India. It is also declared as a classical language by the government of India....
equivalents in alternation. The 7 sols of the week, similarly, were provisionally named after the Sun,
MoonThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
and the 5 brightest planets as seen from Mars — including Earth. The
Darian Defrost Calendar, for instance, creates new names for the Martian months out of patterns relating letter choice and name length to month order and season. The
Utopian Calendar, devised by the Mars Time Group in 2001, has additional suggestions for nomenclature modification.
Martiana Calendar
In 2002 Gangale devised a variant of the Darian calendar that reconciles the months and the sols of the week in a repeating pattern and removes the need to omit days of the week. In the Martiana variant, all the months in a given quarter begin on the same sol of the week, but the sol that begins each month shifts from one quarter to the next.
The following table shows the sol of the week on which each month in the quarter begins. The first quarter corresponds to spring in the Martian northern hemisphere and autumn in the Martian southern hemisphere.
| |
First quarter |
Second quarter |
Third quarter |
Last quarter |
| Even-numbered years |
Sol Solis |
Sol Saturni |
Sol Veneris |
Sol Jovis |
| Odd-numbered years |
Sol Mercurii |
Sol Martis |
Sol Lunae |
Sol Solis |
The leap sol occurs at the end of odd-numbered years as in the original Darian calendar. Since the last month of odd-numbered years contains 28 sols, the following year also begins on Sol Solis, resulting in a two-year cycle over which the relationship of the sols of the week to the months repeats. The sol that is added every tenth year is epagomenal (not counted as part of the week), thus the two-year rotation of the sols of the week is not disrupted. The Martiana scheme avoids the Darian calendar's need to shorten the week to six sols three to four times per year. The disadvantage is that the scheme results in a two-year cycle for reconciling the sols of the week and the months, whereas the Darian calendar is repeatable from month to month.
Other Darian calendars
In 1998 Gangale adapted the Darian calendar for use on the four Galilean moons of
JupiterJupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with a mass slightly less than one-thousandth that of the Sun but is two and a half times the mass of all of the other planets in our Solar System combined. Jupiter is classified as a gas...
discovered by Galileo in 1610:
IoIo is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of 3,642 kilometres, the fourth-largest moon in the Solar System. It was named after Io, a priestess of Hera who became one of the lovers of Zeus.With over 400 active volcanoes, Io is the most...
,
EuropaEuropa is the sixth moon of the planet Jupiter. Europa was discovered in 1610 by Galileo Galilei , and named after a mythical Phoenician noblewoman, Europa, who was courted by Zeus and became the queen of Crete...
,
GanymedeGanymede is a moon of Jupiter and the largest moon in the Solar System. Completing an orbit in roughly seven days, it is the seventh moon and third Galilean moon from Jupiter. Ganymede participates in a 1:2:4 orbital resonance with the moons Europa and Io, respectively. It is larger in diameter...
, and
CallistoCallisto is a moon of the planet Jupiter, discovered in 1610 by Galileo Galilei. It is the third-largest moon in the Solar System and the second largest in the Jovian system, after Ganymede. Callisto has about 99% the diameter of the planet Mercury but only about a third of its mass...
. In 2003 he created a variant of the calendar for
TitanTitan , or Saturn VI, is the largest moon of Saturn, the only moon known to have a dense atmosphere,
and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
.
External links