The Darian Calendar is a system of time-keeping designed to serve the needs of any possible future human settlers on the planet Mars. It was created by aerospace engineer and political scientist Thomas Gangale in 1985 and named by him after his son Darius. A Martian is a hypothetical native inhabitant of the planet Mars. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... Aerospace engineering is the branch of engineering that concerns aircraft, spacecraft, and related topics. ... Political science is the field of the social sciences concerning the theory and practice of politics and the description and analysis of political systems and political behavior. ... 1985 (MCMLXXXV) was a common year starting on Tuesday of the Gregorian calendar. ...

Year Length and Intercalation

The basic time periods from which the calendar is constructed are the Martian solar day (sometimes called a sol) and the Martian vernal equinox year, which is slightly different from the tropical year. 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 intercalation formula therefore allocates six 669-sol years and four 668-sol years to each Martian decade. The former (still called leap years 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. Solar time is based on the idea that, when the sun reaches its highest point in the sky, it is noon. ... Various schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars. ... A tropical year is the length of time that the Sun, as viewed from the Earth, takes to return to the same position along the ecliptic (its path among the stars on the celestial sphere). ... Intercalation is the insertioffn of an extra day, week or month into some calendar years to make the calendar follow the seasons. ... A leap year (or intercalary year) is a year containing an extra day or month in order to keep the calendar year in sync with an astronomical or seasonal year. ...

Calendar layout

The year is divided into 24 months. 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. Look up Month in Wiktionary, the free dictionary. ...

The calendar maintains a seven-sol 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. A week is a [ PER [unit]] of time longer than a day and shorter than a month. ...

In the following table, the days of the week are Sol Solis, Sol Lunae, Sol Martius, Sol Mercurii, Sol Jovis, Sol Veneris, Sol Saturni.

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 equinox marking spring in the northern hemisphere of the planet. Mars currently has an axial inclination similar to that of the Earth, so the Martian seasons are perceptible, though the greater eccentricity of Mars' orbit about the Sun compared with that of the Earth means that their significance is strongly amplified in one hemisphere and masked in the other. 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). An equinox is one of two opposite points on the celestial sphere where the celestial equator and ecliptic intersect. ... Axial tilt is an astronomical term regarding the inclination angle of a planets rotational axis in relation to its orbital plane. ... Earth, also known as the Earth or Terra, is the third planet outward from the Sun. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... The Sun is the star of our solar system. ...

Disputed points

Certain details of the Darian calendar have been the subject of dispute. The greatest of these disputes surrounded the selection of the Martian epoch. Originally this was chosen as late 1975 in recognition of the American Viking program as the first fully successful soft landing mission to Mars. This selection came to be seen as excessively parochial, and also resulted in the many telescopic observations of Mars over the past 400 years being relegated to negative dates. The currently favoured epoch, first suggested by Peter Kokh, is in 1609 in recognition of Johannes Kepler's use of Tycho Brahe's observations of Mars to elucidate the laws of planetary motion, and also Galileo Galilei's first observations of Mars with a telescope. In chronology, an epoch is an instant chosen as the origin of a particular time scale. ... 1975 (MCMLXXV) was a common year starting on Wednesday. ... NASAs Viking program consisted of two unmanned space missions to Mars, Viking 1 and Viking 2. ... // Events April 4 – King of Spain signs an edit of expulsion of all moriscos from Spain April 9 – Spain recognizes Dutch independence May 23 - Official ratification of the Second Charter of Virginia. ... This article does not cite its references or sources. ... Tycho Brahe Monument of Tycho Brahe and Johannes Kepler in Prague   , born Tyge Ottesen Brahe (December 14, 1546 – October 24, 1601), was a Danish (Scanian) nobleman best known today as an early astronomer, though in his lifetime he was also well known as an astrologer and alchemist. ... Galileo Galilei (February 15, 1564 – January 8, 1642) was an Italian physicist, astronomer, and philosopher who is closely associated with the scientific revolution. ... 50 cm refracting telescope at Nice Observatory. ...

Nomenclature has also been a subject of dispute, although with somewhat less rancor. The names of the 24 months were provisionally chosen by Gangale as the Latin names of constellations of the zodiac and their Sanskrit equivalents in alternation. The 7 sols of the week, similarly, were provisionally named after the Sun, Moon and the 5 brightest planets as seen from Mars - including the Earth. These choices were also criticized as parochial. As a result, several alternate calendars, identical in design but differing in nomenclature, have been proposed. 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. Latin is an ancient [[Indo-European languages|Indo-well as the Roman CEuropean language originally spoken in Latium, the region immediately surrounding Rome. ... This article or section does not cite its references or sources. ... 360-degree panorama of the night sky with constellations superimposed. ... The Sanskrit language ( , ) is a classical language of India, a liturgical language of Hinduism, Buddhism, and Jainism, and one of the 22 official languages of India. ... Bulk composition of the Moons mantle and crust estimated, weight percent Oxygen 42. ... 2001: A Space Odyssey. ...

The calendar does not preserve the cycle of the days of the week. This would be unacceptable for members of religions that include the seven-day week in their beliefs. It was these religious grounds that prevented the adoption of the World Calendar. It would also be unacceptable for secular people accustomed to a two-day weekend, because the omitted day is always the Martian equivalent of Saturday. A week is a [ PER [unit]] of time longer than a day and shorter than a month. ... This 1768 parchment (612x502 mm) by Jekuthiel Sofer emulated the 1675 Decalogue at the Esnoga synagogue of Amsterdam The Ten Commandments, or Decalogue, are a list of religious and moral imperatives which, according to the Hebrew Bible, were written by God and given to Moses on Mount Sinai in the... The World Calendar is a proposed reform of the Gregorian calendar created by Elizabeth Achelis of Brooklyn, New York in 1930. ... The weekend is a part of the week lasting one or two days in which most paid workers do not work. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

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. For album titles with the same name, see 2002 (album). ...

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.

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 Jupiter discovered by Galileo in 1610: Io, Europa, Ganymede, and Callisto. In 2003, he created a variant of the calendar for Titan. 1998 (MCMXCVIII) was a common year starting on Thursday of the Gregorian calendar, and was designated the International Year of the Ocean. ... Jupiters 4 Galilean moons, in a composite image comparing their sizes and the size of Jupiter (Great Red Spot visible). ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... // Events January 7 - Galileo Galilei discovers the Galilean moons of Jupiter. ... Atmospheric characteristics Atmospheric pressure trace Sulfur dioxide 90% Io (eye-oe, IPA: , Greek Ῑώ) is the innermost of the four Galilean moons of Jupiter. ... Atmospheric characteristics Atmospheric pressure 1 µPa Oxygen 100% Europa (ew-roe-pÉ™, IPA:  ; Greek Ευρώπη) is a moon of the planet Jupiter. ... Atmospheric characteristics Atmospheric pressure trace Oxygen 100% Ganymede (gan-É™-meed, IPA: ; Greek Γανυμήδης) is Jupiters largest moon, and indeed the largest moon in the entire solar system; it is larger in diameter than Mercury but only about half its mass. ... Atmospheric characteristics Atmospheric pressure trace Carbon dioxide 100% Callisto (kÉ™-lis-toe, IPA: ; Greek Καλλιστώ) is a moon of the planet Jupiter, discovered in 1610 by Galileo Galilei. ... Atmospheric characteristics Pressure 146. ...

See also

• Astronomy on Mars
• Timekeeping on Mars

// Seasons Mars has an axial tilt of 25. ... Various schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars. ...

External links

• The Darian Calendar for Mars
• The Calendars of Jupiter
• The Darian Calendar for Titan