Martian Leap Years

The previous post looked at one challenge with designing a calendar for Mars, namely how to vary the number of days per month so that each month corresponds to a change of 30 degrees with respect to the sun. This is a bigger problem on Mars than here on Earth.

That post assumed that a Martian year consisted of 669 sols (Martian days). But a Martin year is not an integer number of sols, just as an Earth year is not an integer number of days. In fact, a Martian year is 668.5991 sols.

One way to handle this would be for 3 out of every 5 years to have 669 sols, with the remaining years having 668 sols. So maybe if the year mod 5 equals 0, 1 or 2 the year would be long, 669 sols, and otherwise it would be short, 668 sols. (This alternation of 3 and 2 reminds me of Dave Brubeck's song Take Five.)

This scheme, which approximates 668.5991 by 668.6, is about as accurate as our Gregorian calendar, which approximates 365.2422 by 365.2425. For more accuracy, Martian's would need something like our leap seconds.

The post Martian Leap Years first appeared on John D. Cook.