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Mars Needs Leap Days Too
- labster 7y agohttps://en.m.wikipedia.org/wiki/Timekeeping_on_Mars https://en.m.wikipedia.org/wiki/Timekeeping_on_Mars I think you’ll want more detail than the article gave.
- jolmg 7y ago> 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?"
- maemilius 7y agoThat may have actually been (slightly?) intentional. When talking about our Sun in the greater context of stars, I've often seen it referred to as "Sol". The best immediate example I have are games like Stellaris or Elite: Dangerous which refer to our home system as the "Sol System" and our star as "Sol", but I recall hearing it in non-sci-fi contexts as well. I'm not really sure how the etymology works out on all of that, though.
- stevula 7y agoIt’s from Latin for “sun”.
- strbean 7y agoIt truly seems like an awful convention compared to the common "<planet> day" or "<planet> hour".
- piinbinary 7y agoMars day Jupiter day Saturn day => Saturnday => Saturday
- irrational 7y agoWe just need to combine English and Spanish: Sun => Sunday Moon (Lunar) => Lunes => Monday Mars => Martes => Tuesday Mercury => Miercoles => Wednesday Jupiter (Jovian) => Jueves => Thursday Venus => Viernes => Friday Saturn => Saturday
- labster 7y agoEnglish already has the same names. Wednesday is Woden's day. Thursday is Thor's Day, Friday is Frigg's day. These are just English translations of the planets associated with the gods. The names of the days of the week are fairly uniform on Earth. Monday (Moon-day) = lunes (spanish) = 月曜日 (japanese - getsuyoubi, moon day). Sunday = 日曜日 (sunday, or almost "sun sun"). These came through China and are very old names -- tying the seven objects you can see move against the background stars (ignoring Uranus if you know where to look) is an idea going back the the classical era.
- btilly 7y agoNote for those reading my sibling comment. As https://norse-mythology.org/gods-and-creatures/the-vanir-gods-and-goddesses/freya/ https://norse-mythology.org/gods-and-creatures/the-vanir-god... points out, Frigg and Freya are ultimately the same goddess.
- thaumasiotes 7y ago> These came through China and are very old names -- tying the seven objects you can see move against the background stars (ignoring Uranus if you know where to look) is an idea going back the the classical era. Well, the Japanese weekday names come to Japanese through China. They don't originate there; the fact that they occur in the same order as the Western days of the week strongly suggests that they didn't develop independently. The native (old) Chinese system divides months into three roughly equal 旬 periods; seven-day weeks aren't part of it.
- reaperducer 7y ago"Today," or "tosol?"
- samatman 7y agoWhich is perfect, by analogy with month and moon. If you spoke a language where the word for sun and day were the same, you'd barely notice.
- SilasX 7y agoAlso (kind of) analogous to the expression “many moons ago” referring to the cycles of the moon.
- deleted 7y ago[deleted]
- bobbylarrybobby 7y agoChinese is one such language. Both “sky” and “sun” are also used for “day”
- samatman 7y agoYep! Ming (明) is my favorite Hanzi, thanks to a lovely weekend spent at Sun-Moon Lake in Taiwan.
- glup 7y agoI do all my Martian timekeeping by Kim Stanley Robinson rules, obviously. Haven't been late for an appointment yet.
- deleted 7y ago[deleted]
- wcoenen 7y ago> That means that when the clock strikes midnight on New Year’s Eve, Earth hasn’t quite circled all the way back to its starting point. Circling back to the starting point would be a sidereal year, which isn't what we want either. What the calendar is trying to synchronize to is not the sidereal year, but the tropical year: the equinoxes and solstices should occur around the same date each year, and the seasons shouldn't shift relative to the calendar over the years. Because of the precession of the earth's axis, this tropical year is about 20 minutes shorter than the sidereal year.
- mertd 7y agoThe solution (adding a day every four years) doesn't seem specific to either.
- nitrogen 7y agoThe exception cases (skip centuries, except every 4th century, etc.) would be different due to the extra 20 minutes.
- im3w1l 7y agoWhy, physically speaking, is the tropical year almost but not quite as long as the sidereal year?
- wcoenen 7y agoThe seasons are caused by the orientation of the Earth's tilted axis relative to the sun. E.g the north pole is tilted towards the sun during summer of the northern hemisphere, and away from the sun in winter. Now imagine the Earth being magically held in place, instead of orbiting around the sun. This would almost stop the seasons from advancing, but not entirely. There would still be a slow 26000 year cycle of the seasons, because the Earth's axis precesses much like a spinning top. It's this effect that speeds up the cycle of the seasons by about 20 minutes each year. (1 year/26000 is about 20 minutes)
- 7y ago
- skizm 7y agoI assume there are people at NASA / SpaceX/ etc. in charge of writing custom MarsDate modules for various languages. Sounds horrible. I'm not even sure we've solved how to deal with dates on earth yet.
- ShinTakuya 7y agoI'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)?
- dahfizz 7y agoI think any interplanetary civilization will be practically forced to use a planet-agnostic time system - a true UTC
- wahern 7y agoThat'd be TCB--https://en.wikipedia.org/wiki/Barycentric_Coordinate_Time https://en.wikipedia.org/wiki/Barycentric_Coordinate_Time But we'd need a different standard if we colonized planets outside our solar system.
- peterburkimsher 7y agoWe haven't figured out how to deal with time on Earth yet! https://infiniteundo.com/post/25326999628/falsehoods-programmers-believe-about-time https://infiniteundo.com/post/25326999628/falsehoods-program...
- dehrmann 7y agoYou also have to somehow synchronize second counters in a way that accounts for relativistic effects.
- jedberg 7y ago“There may come a time — if you have cultural civilizations that are living in this environment and you want to preserve the seasonal significance of a particular date on the calendar — that you would likely introduce some sort of a leap system,” It never occurred to me until reading this that the main reason we care about syncing our calendar to the seasons is mostly cultural. We could easily just count days and have equal months and be done with it if we didn't care about certain days happening in the same season. Very interesting!
- dahfizz 7y agoIn 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.
- btilly 7y agoNot quite on the same day as may be seen that it didn't fall on the same day before or after. But he wanted it to stay close to the equinox.
- PeterisP 7y agoSaying 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.
- JoeAltmaier 7y agoA spacefaring civilization wouldn't care much at all about planetary motion and seasons. They'd likely go 'metric' with time. "See you in a kilosec!" "Oh she got promoted a couple megasecs ago, transferred out." "I've been up for a hectasec; I have to catch some Z's!"\ "I graduated early, only 5 gigasecs old!"
- btilly 7y ago5 gigaseconds is about 150 years, so your "graduated early" indicates some serious life extension technology.
- adeeds 7y agoor relativistic travel
- Aenyn 7y agoAnd a hectosecond (which I assume is what a hectasec is) is just one minute and forty seconds... I hope he would be able to stay awake a little longer than that.
- JoeAltmaier 7y agoWhat would the name be for 100,000 seconds? An earth day is 86400 seconds...
- chrononaut 7y agoSomewhat related to this, back in 2004 the JPL team working on Spirit and Opportunity were given specially-designed wristwatches that matched the 24 hour and 39 minute day on Mars in order to better match the daily working schedule that Mars required.[0] [0] https://mars.jpl.nasa.gov/mer/spotlight/spirit/a3_20040108.html https://mars.jpl.nasa.gov/mer/spotlight/spirit/a3_20040108.h...
- lxmorj 7y agoI bet those watches sell for a pretty penny
- sudhirj 7y agoDoesn't every planet? I'd be astonished if every planet completed a revolution in a perfect multiple of rotation time. Wouldn't it would have to be an engineered system if it did. Or is that just tidal locking? I know the moon does something similar but there it seems like revolution time = rotation time, not perfect multiple.
- twic 7y ago> 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.
- Sharlin 7y agoIt is indeed: > In some cases where the orbit is eccentric and the tidal effect is relatively weak, the smaller body may end up in a so-called spin–orbit resonance, rather than being tidally locked. Here, the ratio of the rotation period of a body to its own orbital period is some simple fraction different from 1:1. A well known case is the rotation of Mercury, which is locked to its own orbit around the Sun in a 3:2 resonance. https://en.wikipedia.org/wiki/Tidal_locking https://en.wikipedia.org/wiki/Tidal_locking
- gowld 7y agoIt rotates three times per 2 revolutions, right?