Martian Calendar

Creating a Martian Calendar has been excellent practice in logical problem solving by extrapolating data from resources I found on the web. It involves using existing algorithms and ideas established in the space exploration community. The next step is to extrapolate from existing time periods of day (sol), week, month, year.

Below are a list of calendars I have created using Microsoft Excel and then exporting using Adobe Acrobat.

Mars Year 39 will run from September 30, 2026 to August 17, 2028 (UTC).
This Martian year is a non leap year at 668 sols.
MarsYear-39_24mo_EarthUT-Sol-Ls_Prohowich Reserved…

Mars Year 38 will run from November 11, 2024 to September 30, 2026 (UTC).
This Martian year is a leap year at 669 sols.
MarsYear-38_24mo_EarthUT-Sol-Ls_Prohowich (Added 2023-01-17)

Mars Year 37 runs from December 25, 2022 to November 11, 2024 (UTC).
This Martian year is a leap year at 669 sols.
MarsYear-37_24mo_EarthUT-Sol-Ls_Prohowich (Added 2023-01-15)

Mars Year 36 runs from February 7, 2021 to December 25, 2022 (UTC). 668 sols.
MarsYear-36_24mo_EarthUT-Sol-Ls_Prohowich_v2 (Errors fixed 2023-01-15)

Mars Year 35 ran from March 22, 2019 to February 7, 2021 (UTC). 669 sols.
MarsYear-35_24mo_EarthUT-Sol-Ls_Prohowich_v2 (Errors fixed 2021-02-21)

Mars Year 34 ran from May 5, 2017 to March 22, 2019 (UTC). 668 sols.

Questions that have been raised:

How is a work schedule already coordinated with Mars rovers?
One day, go to work at 8:00 am, the next day at 8:40 am, 9:20 am, etc. The length of your work day depends on a 2 to 15 minute one-way signal delay and how much daylight your assigned Mars rover is getting.

Are 668 or 669 days (sols) cumbersome?
Is the idea of a month limited to Earth (month /moon)?
12 months or 24 months or other?

Should the 12 months be the same size or 55 or 56 days?
668.8 divided by 12 = 55.73333333…

Should months be determined by the orbital longitude of Mars and seasons?
When does the new year start? (Northern Vernal Equinox seems to be the convention.)
0° = Northern Spring Equinox [/E] Northward bound Equinox.
90° = Northern Summer Solstice [NS] Northern Solstice.
180° = Northern Autumn Equinox [\E] Southward bound Equinox.
270° = Northern Winter Solstice [SS] Southern Solstice.

I have the MNYD: Mars New Years Day starting where the MSD: Mars Sol Day starts at midnight just prior to the Mars Northern Vernal Equinox (an orbital longitude between 359.487° and 0.000°).
MNYE NLD: Mars New Years Eve Non Leap Day is on the 668th sol of the year or 28th of 24 month*. About 41%.
MNYE LD: Mars New Years Eve Leap Day is on the 669th sol of the year or 29th of 24 month*.  About 59%.

Using orbital longitude with 12 months, creates months that range from 46 sols to 67 sols in length. 21 sols difference in the length of the shortest month to the longest month?
Using orbital longitude with 24 months, creates months that are somewhat familiar in length to Earth’s (28 days to 31 days) where they range from 23 sols to 34 sols in length (20 something to 30 something).

The shortest month is near perihelion and the longest month is near aphelion.

How do you determine when a leap year is held and can you call it a leap year if that’s what 59% of years are? Maybe deficient and abundant years?

Here are some external links to some of the places I used in this project.

Dr. Michael D. Allison, NASA Emeritus at GISS in New York City.

Mars24, a must have program for the Mars enthusiast.
Version 8.1.0 was released 2020-04-07 which required Java 8.
[2023-01-15 note: Version 8.3.0 was released 2022-12-30 requires Java 11.]

The Planetary Society’s “Mars’ Calendar” for the Year Number.

As a result of
MARCI and MOC observations of the atmosphere and surface cap in the north polar region of Mars
Bruce A. Cantora, Philip B.James and Wendy M.Calvin
From Icarus, Volume 208, Issue 1, Pages 61-81

This one is my favorite and where I derived my equations.

Other Twitter sites where you may see Mars related material.

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