Lat/Long and timekeeping system for Mars

It took many, many millions of years for life on Earth to adapt to the 24 hour cycle notwithstanding the annual day/night cycle.

The same system which applies on Earth can be transferred in principle to Mars although the proportion of rotations to an annual circuit is different (and the application of a leap day correction) , the orientation of the planet is slightly different giving a more polar climate spectrum to the planet.

On Saturday, December 1, 2018 at 4:46:52 AM UTC-7, Gerald Kelleher wrote:

The Martian Lat/Long system then fits inside this framework where the 24 hours 40 minutes

And, indeed, the Martian day - the solar day, which corresponds to the 24 hour
solar day on Earth - is 24 hours, 39 minutes, and about 35 1/4 seconds.

Whereas stellar circumpolar motion on Mars has a period of 24 hours, 37 minutes,
and about 22 2/3 seconds.

I was looking for an accurate value for Martian circumpolar motion - I thought I
had that on my site as well, and I did, but I just looked in the wrong place -
and found *this* web site...

https://www.windows2universe.org/kids_space/period.html

which says

" Earth's day (or rotational period) is exactly 23.9345 hours (or, 23 hours, 56
minutes, 4.2 seconds)."

If that were true, I would have to set my watch back four minutes every day.
While I disagree with you in that I think that there are good and proper reasons
to view the period of stellar circumpolar motion as the true period of the
Earth's rotation, I know very well, from the natural cycle between light and
dark, warm and cold, that a _day_ on Earth is 24 hours long.

I blame people like them getting the day wrong for the confusion in which you,
in reacting to their error, have placed yourself.

John Savard

The system for astronomical predictions on Earth is based on the calendar system allied with an implied correlation between the Lat/Long system and the 24 hour day hence people can predict events within that format as days and dates using the proportion of rotations to orbital circuits as an integer which can be reduced to a fraction. The Earth's proportion of rotations per orbital circuits is 1461 rotations for 4 orbital circuits.

To apply predictions to observations seen from Mars would require a copy of the structures that exist on Earth so the different frameworks outlined here would provide the necessary narrative for a Lat/Long system on Mars with its own day and leap day correction.

On Sat, 1 Dec 2018 19:04:20 -0800 (PST), Quadibloc
wrote:

I was looking for an accurate value for Martian circumpolar motion - I thought I
had that on my site as well, and I did, but I just looked in the wrong place -
and found *this* web site...

https://www.windows2universe.org/kids_space/period.html

which says

" Earth's day (or rotational period) is exactly 23.9345 hours (or, 23 hours, 56
minutes, 4.2 seconds)."

I'm not sure what you're objecting to. The failure to qualify "day" as
"stellar day"? That seems pretty minor considering that the sentence
immediately before the one you quote very explicitly defines "day" as
the rotational period... which obviously is the value they state.

In many contexts, "day" is reasonably assumed to mean "solar day", but
I don't see the problem if the context makes it clear what kind of day
is under discussion (and the word "day" in isolation is always
ambiguous in meaning).

On Sunday, December 2, 2018 at 3:33:31 PM UTC-7, Chris L Peterson wrote:
On Sat, 1 Dec 2018 19:04:20 -0800 (PST), Quadibloc
wrote:

I was looking for an accurate value for Martian circumpolar motion - I thought I
had that on my site as well, and I did, but I just looked in the wrong place -
and found *this* web site...

https://www.windows2universe.org/kids_space/period.html

which says
" Earth's day (or rotational period) is exactly 23.9345 hours (or, 23 hours, 56
minutes, 4.2 seconds)."

I'm not sure what you're objecting to. The failure to qualify "day" as
"stellar day"? That seems pretty minor considering that the sentence
immediately before the one you quote very explicitly defines "day" as
the rotational period... which obviously is the value they state.

The sentence immediately before was:

'We call the rotational period of Earth a "day".'

It was not obvious what value of "we" should be applied to that sentence. Usually, sentences like this beginning with "we" give it the meaning 'the general community of speakers of English', as in:

When the local government demands a portion of your earnings by force, we call it "taxes" rather than a protection racket.

Thus, I find that sentence to aggravate rather than ameliorate the issue.

In many contexts, "day" is reasonably assumed to mean "solar day", but
I don't see the problem if the context makes it clear what kind of day
is under discussion (and the word "day" in isolation is always
ambiguous in meaning).

Basically, although I recognize what he is wrong about, I still would stand with
Oriel on *this* point.

Earth's day is 24 hours. Period. Full stop. The only if, and, or but to that I
accept is the one he would call "pretentious" - including a tiny fraction of a
second, since it _is_ slightly longer than 86,400 SI seconds, or 86,400 of the
Ephemeris seconds on which their length was based.

Yes, there are contexts where one could put the synodic day and the sidereal day
on an equal footing - and the tropical, sidereal, and anomalistic years as well.
Those are technical contexts, for the use of astronomers in communicating with
other astronomers.

Not for anything intended to face members of the general public, or, worse yet,
children.

Oriel errs by insisting that Earth's day must also be its rotational period -
that previous error makes the same error of equating the two, but in the
opposite direction! It is precisely this sort of sloppiness that *created* Oriel
in the first place!

John Savard

The creation of a timekeeping system for Mars will include weeks, months and years/leap years that mirror the Earth's timekeeping structure in principle but adapted to different weeks and months within a framework that is presently calculated as 687 Earth days ( Earth day/night cycles).

Timekeeping is anchored to noon which also carries along sunrise/sunset as a function of the day/night cycle. The Earth has two distinct day/night cycles - the 24 hour day/night cycle and the Polar day/night cycle.

A space age race of people shouldn't find the experience of separate day/night cycles difficult as their combination generates the seasons which are arbitrary divisions of the annual cycle into 4 components. The ancient Celtic year is more accurate as it breaks the year into a light half and dark half thereby represents the rotation behind the annual day/night cycle as being a rotation parallel to the orbital plane.

The foundation of a distinct timekeeping system for Mars along with a Lat/Long system can be accomplished in a straightforward and neat way compared to the thousands of years that went into timekeeping evolution on Earth, at least the one we inherit today.

Such a development doesn't require actors who are lost or behave like some politicians who say nothing while appearing to say something as the two nuisances in this thread have shown.

On Sun, 2 Dec 2018 18:00:00 -0800 (PST), Quadibloc
wrote:

In many contexts, "day" is reasonably assumed to mean "solar day", but
I don't see the problem if the context makes it clear what kind of day
is under discussion (and the word "day" in isolation is always
ambiguous in meaning).

Basically, although I recognize what he is wrong about, I still would stand with
Oriel on *this* point.

Earth's day is 24 hours. Period. Full stop.

Well, if you leave it there, I'd say you're guilty of the same thing
you're objecting to in the page you referenced. Because "day" is
ambiguous. If you're making a statement intended to be accurate,
intended to be clear, you need to qualify the word. There are
different kinds of days, and the one you are referring to is either
determined by qualification or it is determined by context. You
provide neither in your example. The page you are objecting to,
however, does. It is very clear that it is discussing "day" in the
sense of stellar day, that it is talking about the time to make one
rotation.

On Sun, 2 Dec 2018 18:00:00 -0800 (PST), Quadibloc
wrote:

Earth's day is 24 hours. Period. Full stop.

Correct. The solar day is 24 solar hours, and the sidereal day is 24
sidereal hours.

Simple, isn't it? All you have to think about is to match your
selected type of day to the appropriate type of hour.

The last word on this is that the Lat/Long system in tandem with the 24 hour system fits inside the calendar framework and uses noon as an anchor for converting the total length of the natural noon cycle to an average 24 hour day which in turns generates equable hours,minutes and seconds.

Stellar circumpolar motion is not anchored in anything other than the return of the stars using the average 24 hour day which happens to work with Lat/Long across the geometry and geography of the Earth.

The 23 hour 56 minute 04 second value uses the 24 hour average day and assigns cause directly between daily rotation and stellar circumpolar motion. The horrible notion is that the 3 minute 56 second drift occurs day on 24 hour day until there are more rotations than 24 hour days -

" It is a fact not generally known that,owing to the difference between solar and sidereal time,the Earth rotates upon its axis once more often than there are days in the year" NASA /Harvard


Instead of being anchored to noon with sunrise/sunset symmetrical to this event due to one rotation each day, the celestial sphere guys went their own way and conjured up something as dumb as that.

Needless to say, the nuisances in this newsgroup will have no input into discussing a Lat/Long and timekeeping system for Mars with Martian years/leap year, a Martian day with its own equable hours, minutes and seconds in order to fix events now and in future.

On Mon, 03 Dec 2018 16:19:39 +0100, Paul Schlyter
wrote:

On Sun, 2 Dec 2018 18:00:00 -0800 (PST), Quadibloc
wrote:

Earth's day is 24 hours. Period. Full stop.

Correct. The solar day is 24 solar hours, and the sidereal day is 24
sidereal hours.

Except there's no formal definition of a "sidereal hour". A sidereal
day is not defined in terms of sidereal hours, but in terms of
seconds.

The only widely recognized, semi-formal definition of "solar day" is
86,400 seconds; the idea of a solar day being the length of time for
the Sun to return to the meridian is colloquial.

A sidereal or stellar day is taken as the time for a given fixed point
on the celestial sphere to return to the same longitude, or for the
Earth to make one complete revolution. The mean period for that can be
expressed in seconds, but not in "sidereal hours".