Telling Time on Mars

The Martian day is (approximately) 24 hours, 39 minutes, and 35.26
seconds long.

Given that the second is one of the basic units of the metric system,
it would be desirable to use the Earth second as part of Martian
timekeeping if people from Earth were to live on Mars.

One scheme that has been suggested is to have the Martian day consist
of 25 hours, each hour consisting of 53 minutes, and each minute
consisting of 67 seconds.

This accounts for the 88775 seconds in a day, but there would need to be a leap second every four days or so.

However, all these odd numbers are reminiscent of the Hogwarts currency system. And leap seconds are a pain. So if one is going to avoid them with a Martian civil second that is slightly different from the SI second - a remedy that could also be used to avoid the potential for Internet chaos with the leap second on Earth - perhaps an even larger discrepancy could permit a timekeeping system more fully in accord with Earthly habits of thought.

Given that the Martian day is very close to 24 hours and 40 minutes,
I thought, why not just do this:

The hour hand sweeps out a full circle, once a Martian day, past 74
tick marks on the clock face. 0, 1, 2... 24 would mark every third
tick, but the span from 24 to 0 would only be two ticks long.

The minute hand would go around the face of the clock once every 20
Martian minutes, and the second hand would take one Martian minute,
so they'd go past 60 ticks, with every third tick being bigger.

12h 00m would be noon; 24h 20m would be midnight. 0h 00m would be one
second after 24h 39m 59s.

This was pretty good, but it still had one shortcoming; usually, with
Earthly habits of thought, we divide the hour into halves and
quarters rather than thirds.

So an even cuter idea occurred to me: Let a Martian watch look almost
exactly like an Earth watch, but with one of those small extra dials.

The small extra dial contains a hand that goes around once every 20
minutes. That hand, and the second hand, move continuously.

The conventional hour hand and minute hand, however, stop moving for
40 minutes each day, between 24h one day and 0h the next day. That's
easy enough to achieve with simple gearing, and so when those hands
show midnight, you would look at the little dial to see what time it
really was.

John Savard

On Thu, 21 Jan 2016 10:01:13 -0800 (PST), Quadibloc
wrote:

The Martian day is (approximately) 24 hours, 39 minutes, and 35.26
seconds long...

Some cute solutions, and a fun thing to play around with. But I
suspect that if we ever colonize other bodies, we'll simply adopt
timekeeping systems that are dynamically convenient (on Mars, that
means the same one we use on Earth with everything adjusted for the
different day length), and simply no worry about the disconnect
between those civil systems and SI seconds. We're not far from doing
that right here on Earth- disconnecting the second from civil time.

Quadibloc:
The Martian day is (approximately) 24 hours, 39 minutes, and 35.26
seconds long.

Given that the second is one of the basic units of the metric system,
it would be desirable to use the Earth second as part of Martian
timekeeping if people from Earth were to live on Mars.

Since humans won't be living on Mars, and Mars cannot be made
habitable, the whole question is moot for most purposes. I'm sure it's
of concern to those who manage Mars-orbiting observatories and rovers
on Mars, but for the rest of us the time of day on Mars is utterly
irrelevant, except possibly as a curiosity. I'm a curious person, but
the time of day on Mars is not on the list of things I'm curious about.
If I were, however, there's are apps for that
https://itunes.apple.com/us/app/mars-clock/id532009322?mt=8.

--
I agree with almost everything that you have said and almost everything that
you will say in your entire life.

usenet *at* davidillig dawt cawm

On Thursday, January 21, 2016 at 1:01:17 PM UTC-5, Quadibloc wrote:

So an even cuter idea occurred to me: Let a Martian watch look almost
exactly like an Earth watch, but with one of those small extra dials.

The small extra dial contains a hand that goes around once every 20
minutes. That hand, and the second hand, move continuously.

The conventional hour hand and minute hand, however, stop moving for
40 minutes each day, between 24h one day and 0h the next day.

That idea was used in the Mars Trilogy (Red, Green & Blue Mars) by Robinson.

Quadibloc wrote:
The Martian day is (approximately) 24 hours, 39 minutes, and 35.26
seconds long.

Given that the second is one of the basic units of the metric system,
it would be desirable to use the Earth second as part of Martian
timekeeping if people from Earth were to live on Mars.

One scheme that has been suggested is to have the Martian day consist
of 25 hours, each hour consisting of 53 minutes, and each minute
consisting of 67 seconds.

This accounts for the 88775 seconds in a day, but there would need to be
a leap second every four days or so.

However, all these odd numbers are reminiscent of the Hogwarts currency
system. And leap seconds are a pain. So if one is going to avoid them
with a Martian civil second that is slightly different from the SI second
- a remedy that could also be used to avoid the potential for Internet
chaos with the leap second on Earth - perhaps an even larger discrepancy
could permit a timekeeping system more fully in accord with Earthly habits of thought.

Given that the Martian day is very close to 24 hours and 40 minutes,
I thought, why not just do this:

The hour hand sweeps out a full circle, once a Martian day, past 74
tick marks on the clock face. 0, 1, 2... 24 would mark every third
tick, but the span from 24 to 0 would only be two ticks long.

The minute hand would go around the face of the clock once every 20
Martian minutes, and the second hand would take one Martian minute,
so they'd go past 60 ticks, with every third tick being bigger.

12h 00m would be noon; 24h 20m would be midnight. 0h 00m would be one
second after 24h 39m 59s.

This was pretty good, but it still had one shortcoming; usually, with
Earthly habits of thought, we divide the hour into halves and
quarters rather than thirds.

So an even cuter idea occurred to me: Let a Martian watch look almost
exactly like an Earth watch, but with one of those small extra dials.

The small extra dial contains a hand that goes around once every 20
minutes. That hand, and the second hand, move continuously.

The conventional hour hand and minute hand, however, stop moving for
40 minutes each day, between 24h one day and 0h the next day. That's
easy enough to achieve with simple gearing, and so when those hands
show midnight, you would look at the little dial to see what time it
really was.

John Savard


People working with Mars rovers use watches calibrated to Martian time with
one Martian day as 24 hours and therefore a longer second.
These are set to local mean solar time zones.

On Thursday, January 21, 2016 at 1:54:00 PM UTC-7, wrote:

That idea was used in the Mars Trilogy (Red, Green & Blue Mars) by
Robinson.

Really? I must have forgotten.

Actually, though, I wouldn't be surprised if in those novels, they
used watches that stopped for 39 minutes and 35.26 seconds each
day.

My idea was a bit more complicated than that.

First, I proposed that Martian watches be calibrated to a slightly
shorter second, so that a Martian day would be _exactly_ 24 hours
and 40 minutes.

Then, I proposed that while the hour and minute hands would be
disengaged for 40 minutes each day - and otherwise work like those
on a conventional Earth watch - a second hand, and a hand on a
smaller dial the circumference of which covered a span of 20
minutes - would continue to move. Thus, during the entire day, not
just the day exclusive of the 'dead' 40 minutes, one could look at
the watch and see the exact time.

I don't _think_ I've ever seen _that_ idea before, although it's
entirely possible that someone could have come up with it before
me.

John Savard

On Thursday, January 21, 2016 at 11:12:58 AM UTC-7, Chris L Peterson wrote:
But I
suspect that if we ever colonize other bodies, we'll simply adopt
timekeeping systems that are dynamically convenient (on Mars, that
means the same one we use on Earth with everything adjusted for the
different day length), and simply no worry about the disconnect
between those civil systems and SI seconds.

That may be.

But under some sets of circumstances - and, of course, if Mars is
ever colonized, which itself is not certain, the precise
circumstances of that colonization could take many forms - instead
of trying to start fresh, and adapt a timekeeping system to Mars'
own natural rhythms, it could well be that the Martian colonists
would feel a pressing need to keep their clocks and calendars as
closely related to Earth timekeeping as possible.

For example, they might import all their TV shows from Earth, and
so using the Earth hour or a very close approximation thereto
would facilitate scheduling programs! (Of course, who watches TV
today now that we have the Internet - but they might also import
school textbooks and lesson plans and union contracts and
cookbooks...)

Similarly, the Jewish and Chinese calendars use a year that can be
either 12 or 13 months, so that they can use both solar years and
lunar months.

So I proposed a Martian calendar might have either 22 or 23
months, so that they could use a month that's exactly 1/12 of an
_Earth_ year - to facilitate calculating rents, paycheques, bank
interest, whether someone is old enough to vote, and so on and so
forth. So in addition to the year, the "twelvemonth", basically an
Earth year, would be an important Martian unit of time.

Basically, this makes sense if, instead of being isolated and independent, Mars is closely and intimately tied in with the Earth economy and so on, so that it is necessary to design a Martian timekeeping system so that it somehow accomplishes the contradictory goals of reflecting Mars' orbital and rotational cycles on the one hand, and interoperating with the clocks and calendars of Earth on the other.

That seems to be the case which would be nontrivial, and require
some ingenuity.

John Savard

On Thursday, January 21, 2016 at 3:51:42 PM UTC-7, Quadibloc wrote:

Basically, this makes sense if, instead of being isolated and
independent, Mars is closely and intimately tied in with the Earth
economy and so on, so that it is necessary to design a Martian
timekeeping system so that it somehow accomplishes the
contradictory goals of reflecting Mars' orbital and rotational
cycles on the one hand, and interoperating with the clocks and
calendars of Earth on the other.

I missed adding line breaks to that paragraph to make it easy to
read for everyone.

John Savard