Space Calendars

Originally on the IFC calendar page, which has since become the 3-Way Calendar Converter page.

Smarch: A Calendar Misprint

It all started on the 13th hour, of the 13th day, of the 13th month. We were there to discuss the misprinted calendars the school had purchased.

"Smarch" is a fictional month featured in Treehouse of Horror VI

The month is a result of a misprinting of the calendars in Springifield, resulting in a 13th month which is 28 days long.

https://www.google.com/amp/s/amp.reddit.com/r/TheSimpsons/comments/765u6m/it_all_started_on_the_13th_hour_of_the_13th_day/

Despite Marge Explaining it is the 13th hour, that being 1 PM, the school meeting takes place at night. Specifically, 2 minutes and 39 seconds into the episode, an analog clock reads 9:05. Considering it is night time, it can be inferred it is 9:05 PM

Martian Calendar

The first 5 months of each quarter have 28-day months, the final month in each quarter has 27. The final month of the year also has only 27 days, unless its a leap year. Each year starts on Sunday for consistency and neatness. If the year doesn't end on Saturday, it goes to Sunday, anyway.

The calendar maintains a 7-sol week, and the months are the smae length as the months of the 13 month calendar (28 days = 4 weeks)

In the table, the sols of the week are Sol Solis, Sol Lunae, Sol Martis, Sol Mercurii, Sol Jovis, Sol Veneris, Sol Saturni.

The last sol of Vrishika is an intercalary sol that only occurs on leap years, much like February 29 in the Gregorian calendar.

Terranova - Mass Effect

*The video game doesn't feature a calendar for the planet.

1 year = 1.5 Earth years
1 day = 37.3 Earth hours
24/37.3 = 0.64343163538
1.5 * 365.24217 = 547.863255 Earth days
547.863255*0.64343163538 = 352.512550129 Terranova Days
1/0.512550129 = A leap day every 1.95102867685 years
352 days in a common year
352/7 = 50.2857142857 weeks
50 * 7 = 350
2 extra days.
350/28 = 12.5
12 months of 28
Two extra weeks and two extra days. One extra week and one extra day either added on 6th and 12th month.

Or:
10 months of 35 days
350/35 = 10
Two extra days: One extra day on 5th and 10th month.

*Intercalendary day: doesn't fall on any day of the week.

Length of the week is the same across all planets.