View of Mars at its 2001 opposition from Hubble Space Telescope on June 26, 2001. "The colors have been carefully balanced to give a realistic view of Mars' hues as they might appear through a telescope."

THE THING ABOUT CALENDARS

 

From Wikipedia, the free encyclopedia

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.

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.

 

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.

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.

 

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 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.

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MORE SPACE TRIPPING CALENDAR INFORMATION AT

http://en.wikipedia.org/wiki/Darian_calendar

 

Image: http://en.wikipedia.org/wiki/Image:Mars_Hubble.jpg

NASA Image PIA03154; Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) [1] Acknowledgment: J. Bell (Cornell U.); This file is in the public domain because it was created by NASA. NASA copyright policy states that "NASA material is not protected by copyright unless noted".