Not to be confused with Mars bar....
A well-known Swiss watch maker is now selling a watch indicating Mars time. Which triggered an excursion into Mars time.
Time is relative, said a famous physicist. And indeed, time is passing on and we seldomly muse about things. Why does the year on Earth start on January 1st? It makes no astronomical sense on the orbit of the Earth.
And we know that a second is no longer 1/86400 of a terrestial solar day, but rather some number of atomic oscillations. And solar years vary in length, leap years have funny rules, and leap seconds are totally arbitrary and may be banned in the future.
What then is the time on Mars, the neighboring outward planet in our solar system and sometimes a mere 62.07 million kilometers away?
Interestingly it has an almost identical solar day which is about 40 minutes (2.75% or 39 minutes 35 seconds to be more precise) longer than an average solar Earth day. So it makes sense to think of "Mars day" which is called sol. (All of this can be read-up of course in Wikipedia or on a NASA web-site.)
Mars hours, minutes, and seconds can be defined as on Earth by dividing things by 24, 60 and 60 again. There is a definition of longitude which defines a Martian Time Coordinate (MTC) similar to Earth's GMT for which London was assumed to be at longitude 0.
Mars years too can be defined similarly to Earth years: one trip around our beloved star, the sun. But this takes longer than on Earth: about 2 years (686.98 Earth solar days to be more precise). The problem however is to define the notion of Mars month. Although Mars has two moons, these are useless for a humanly comprehensible definition of a month since they whizz around the red planet rather quickly (and are scheduled to crash too in the case of Phobos).
This has lead to some tinkering by clever people to invent a calendar for Mars. The Darian Calendar by Thomas Gangale seems to comprehensible. It divides a Mars year into 24 "months", each of 27 or 28 days. Months are named according to the Zodiacs and their Sanskrit names. Leap years are also defined. Epoch of the Darian Calendar is March 11, 1609 - the year Mars was first observed via telescope by Galileo Galielei - and the calendar started with 1. Sagitarrius 0000.
Interestingly a week also has seven sols, named with Latin weekday names. Easy for many languages to grasp. A problem remains with months of 27 sols: not an integer number of 7 sol weeks.... The Darian Calendar fixes this by dropping the last Saturday (Saturni) and just starting with next first of the month on a Sunday (Solis). If we ever live on Mars, we might get used to it; a given sol of a Mars month is always on the same week-sol.
And another interesting fact on Mars time: the seasons are different in length, since the Mars orbit is not as well centered as the one of Earth. Which means winter or summer are not of equal length; given a preference for summer or winter you can move to the northern or southern Mars hemisphere, just in case.
So much for some ramblings on Mars time. Makes you wonder about the miracle of Earth (seasons, climate, life) when the next neighbor is already so different. Needless to say that pictures of the Webb telescope would make you wonder even more (unless they simply are the result of some AI gone wild? Just kidding!) about time, life, and the meanings thereof.
Last but not least, we can pour the Darian Calendar into some computer code and display it in your preferred browser (assuming it interpretes the JavaScript version du jour).