Mars Needs Leap Days Too

The solution (adding a day every four years) doesn't seem specific to either.

Why, physically speaking, is the tropical year almost but not quite as long as the sidereal year?

5 gigaseconds is about 150 years, so your "graduated early" indicates some serious life extension technology.

Verner Vinge used that system in A Deepness in the Sky. You get used to it after awhile.

> A spacefaring civilization wouldn't care much at all about planetary motion and seasons.

Given france’s failed attempt at rational time, what does that say about us as a species?

Relativity says it’s impossible for two observers to agree on things like simultaneity, distance, duration, etc. Without reference to astronomical landmarks (observed within a given proximity of the solar system, at low speed) how could anyone agree on the meanings of time intervals?

When you go from Casablanca to Detroit, when you arrive, you adjust to Detroit time (as well as weather, etc.) because this is the place your are in, and only take the pain to compute/represent yourself time in Singapore when you communicate with someone over there (instantly in that case).

When you travel by boat from Southampton to Auckland, during the travel, you mostly only care about the flow of time on the boat, where it is, regardless of the time in the departure & arrival places. You only expect to be in Auckland, around a certain local time.

Going from Earth to Mars, or from the solar system to an Aldebaran planet is slightly the same (but that the flow of time itself may be relative between the places you left/arrived at, and the place you are):

- you expect to be somewhere in the future in about a relative time to where you are (I'll be there in what I know/can represent myself to be X-earth-years);

- you will account for inevitable delays during travel, that might be significant at your scale, but not to others';

- when arrived there, you'll try adjust to the local time keeping method that makes sense to locals - if only because that's how you will interact with them about the flow of time.

You may get to compute what's the relative time on Earth, at the same instant, or when they will get your message. Just as everyone do today (and before) when communicating through slow (aka, human-borne) package & mail delivery.

We can consider having an atomic (or similar) clock that pulse at the same rate, on both Aldebaran & Earth. But:

1. would they be still in sync? experience seems to say no; do we know how we would be even in a position to check that remotely?

2. would it be relevant, relative to Aldebaran-time-keeping? (the atomic second as it is used on Earth is 1/86400th of a full Earth day; it may be wildly on a different planet)

I bet those watches sell for a pretty penny

> The term sol is used by planetary scientists to refer to the duration of a solar day on Mars. The term was adopted during the Viking project in order to avoid confusion with an Earth day. By inference, Mars' "solar hour" is 1/24 of a sol, and a solar minute 1/60 of a solar hour.

I wish they would have picked another name. As a Spanish speaker, I can't stop my mind translating "sol" to "sun". I can already imagine hearing someone say, "how was your sun today?"

I do all my Martian timekeeping by Kim Stanley Robinson rules, obviously. Haven't been late for an appointment yet.

I'd be more interested to see if a more generalised PlanetDate module could be written. Perhaps outside of Earth we could do away with months and just stick to days (based on rotations, assuming the planet rotates) and years, with leap days added in between? And if the planet doesn't rotate, just count by hours and years (with hours having a logical separator at 10 or 100)?

We haven't figured out how to deal with time on Earth yet!

https://infiniteundo.com/post/25326999628/falsehoods-program...

You also have to somehow synchronize second counters in a way that accounts for relativistic effects.

In fact, it was the Catholic church that officially declared the Gregorian calendar we use today. The motivation was to make sure Easter always fell on the same day.

Saying that it's mostly cultural IMHO misses the point - having certain days happening in the same season is the whole point of having calendars; unlike the length of weeks and months (which are arbitrary and cultural) there are practical reasons to require an accurate metric for years that doesn't shift seasons around because that affects our agriculture.

For much of human history, farmers needed to know that (for example) this spring is later or earlier than usual, because that affects the length of the growing season they'll see - if they would just start planting solely based on the weather conditions, that's not the best way to go.

Nowadays we could just "directly" make weather predictions based on all kinds of factors, so today we could decouple calendar from seasons if we wanted to, but historically having a calendar that is (for example) two weeks off of traditional seasons would be a bad thing. Sure, you could just learn to adjust, but if you're adjusting anyway, why not adjust the calendar directly - since the vast majority of people were either farmers or derived their income from farming (i.e. landlords / aristocrats), the practical needs of the farming industry outweighed pretty much every other factor.

> But there is one planet where the calendar would need zero finessing: Mercury. The small planet revolves exactly three times, or days, over the course of two years — allowing its calendar to naturally align every other year.

I would imagine that this is some form of resonance, like the tidal locking of the moon, but i can't explain it myself.