Entry tags:
Happy New Year
Used to be that Britain and the Colonies, and even the US after we became independent changed the year on March 25th. Really.
Entry tags:
more solar calendars
Ok, the other day I went into how you could set up markers for the solstices, equinoxes and the cross-quarter days.
That seems to have been popular in Britain and western Europe.
I the American Southwest, the natives did it differently.
They set up sun daggers.
https://en.wikipedia.org/wiki/Fajada_Butte
They started with a spot where sunlight coming thru a gap in a formation created a wedge shape spot of sunlight on a rock wall. Then they marked where the point was on the summer solstice. They placed petroglgyphs on the rock face to mark this.
Interesting solution to a "common" problem.
That seems to have been popular in Britain and western Europe.
I the American Southwest, the natives did it differently.
They set up sun daggers.
https://en.wikipedia.org/wiki/Fajada_Butte
They started with a spot where sunlight coming thru a gap in a formation created a wedge shape spot of sunlight on a rock wall. Then they marked where the point was on the summer solstice. They placed petroglgyphs on the rock face to mark this.
Interesting solution to a "common" problem.
Entry tags:
clocks and calendars
I'm reading a story about some folks throw back in the distant past. They are talking about how to determine the season and set up a calendar. They aren't doing too bad, but they obviously don't know a couple of important tricks.
Ok, for time of day, set up a crude sundial to start. Just a flat piece of cleared ground with a tall stick or pole in the middle.
Have someone keep an eye on it and set small stones at the end of the shadow every so often, or poke twigs in the ground.
After a few days you'll have the longest shadow pinned down, and that's noon. If you still have working watches or clocks, you can use those to lay out markers for the hours. Just remember that you'll have to shift them every week or two.
For setting up a calendar, you need a hunk of flat ground with a good view of the horizon (east or west) so you can observe surise or sunset.
It works best if the horizon is flat, but you can still work with it even if its hilly.
Set up a pole just tall enough that you can sight over the top. Use a rope or cord to darw a circular arc around it in the direction of sunrise or sunset.
Each day at sunrise, have one person at the sighting stick and another with a tall pole standing on the arc. Use hand signals to move them right or left until the pole lines up with the rising/setting sun. Place a marker on the arc at that point.
Over the course of the year, the markers will shift to one side until they hit a max and start moving back. Those two ends of the arc mark the solstices. The point in the middle of the arc marks the equinoxes.
Most ultures also noted the points halfway in between the solstices and the equinoxes. Those are the cross-quarter days.
All 8 points (remember the ends only get hit once a year while the other six get hit twice a year) are festivals. Because they are important seasonal markers if you are outside the tropics.
You've got about 45 days between each, which is good enough for a crude calendar.
If you've got more gear you can do better on the sundial. Use a rod pointing at the Celestial pole, and a couple of half-circle bands to support it. The hour marks on the band at right angles to the rod will be evenly spaced and not need to be changed over the course of the year.
Ok, for time of day, set up a crude sundial to start. Just a flat piece of cleared ground with a tall stick or pole in the middle.
Have someone keep an eye on it and set small stones at the end of the shadow every so often, or poke twigs in the ground.
After a few days you'll have the longest shadow pinned down, and that's noon. If you still have working watches or clocks, you can use those to lay out markers for the hours. Just remember that you'll have to shift them every week or two.
For setting up a calendar, you need a hunk of flat ground with a good view of the horizon (east or west) so you can observe surise or sunset.
It works best if the horizon is flat, but you can still work with it even if its hilly.
Set up a pole just tall enough that you can sight over the top. Use a rope or cord to darw a circular arc around it in the direction of sunrise or sunset.
Each day at sunrise, have one person at the sighting stick and another with a tall pole standing on the arc. Use hand signals to move them right or left until the pole lines up with the rising/setting sun. Place a marker on the arc at that point.
Over the course of the year, the markers will shift to one side until they hit a max and start moving back. Those two ends of the arc mark the solstices. The point in the middle of the arc marks the equinoxes.
Most ultures also noted the points halfway in between the solstices and the equinoxes. Those are the cross-quarter days.
All 8 points (remember the ends only get hit once a year while the other six get hit twice a year) are festivals. Because they are important seasonal markers if you are outside the tropics.
You've got about 45 days between each, which is good enough for a crude calendar.
If you've got more gear you can do better on the sundial. Use a rod pointing at the Celestial pole, and a couple of half-circle bands to support it. The hour marks on the band at right angles to the rod will be evenly spaced and not need to be changed over the course of the year.
Entry tags:
Religions, time and other worlds
Now let's get into the fun relationships between various religions and the clock/calendar and how this can mess things up on other planets.
The various Abrahamic religions (Judaism, Christianity and Islam) all have their own calendars, with various relationships to the sun and moon. The Baha'I have yet another calendar, but share the 7-day week with the other three.
Judaism and Islam have the day starting with sunset. *Actual* sunset.
This led to problems when Jews started living around and above the Arctic circle. As I understand it, this led to a ruling that in cases where the sun is not practical to use, you use the sunset in Jerusalem.
To the best of my knowledge, Islam has not yet dealt with this.
Christian monks were one of the drivers behind clocks in the Western world, so the Catholic church and its descendants pretty much run on clock time, not solar time. The Liturgy of the Hours (and the canonical hours based on it) follow clock time for the most part.
Islam definitely runs on solar time. There's a simple test for when the daylight (and thus things like the daylight fasting in Ramadan) begins. It's when you can tell the difference between a white thread (hair) and a black one laying in the palm of your hand. A quick search for an equally clear definition of sunset didn't turn up anything equally simple, but from the learned arguments I encountered, it is most definitely an *observation al* event, not a calculated or clock based one.
Islamic prayer times are equally tied to the sun.
So what Moslems on Mars or some planet around another star will do is unknown. If I had to guess, they might go with Mecca the way Jews did with Jerusalem. Or they might go with local solar time.
Now we have the week. this gets *really* problematic, because it's supposed to be important to take a *specific* day of the week as a day of rest. No putting it off or doing it early. It has to be *that* day.
Now, using Mars as an example, from my previous post, we know that 36 Martian sols is a bit over 37 days. Which means that you'd be taking that day of rest a day late! Not good.
Trying to stick with the earth-based week for this will be a pain. And various religious authorities *will* Have Opinions On This.
Beyond the week we've got months and various holy days (holidays) based on the year.
( Read more... )
The various Abrahamic religions (Judaism, Christianity and Islam) all have their own calendars, with various relationships to the sun and moon. The Baha'I have yet another calendar, but share the 7-day week with the other three.
Judaism and Islam have the day starting with sunset. *Actual* sunset.
This led to problems when Jews started living around and above the Arctic circle. As I understand it, this led to a ruling that in cases where the sun is not practical to use, you use the sunset in Jerusalem.
To the best of my knowledge, Islam has not yet dealt with this.
Christian monks were one of the drivers behind clocks in the Western world, so the Catholic church and its descendants pretty much run on clock time, not solar time. The Liturgy of the Hours (and the canonical hours based on it) follow clock time for the most part.
Islam definitely runs on solar time. There's a simple test for when the daylight (and thus things like the daylight fasting in Ramadan) begins. It's when you can tell the difference between a white thread (hair) and a black one laying in the palm of your hand. A quick search for an equally clear definition of sunset didn't turn up anything equally simple, but from the learned arguments I encountered, it is most definitely an *observation al* event, not a calculated or clock based one.
Islamic prayer times are equally tied to the sun.
So what Moslems on Mars or some planet around another star will do is unknown. If I had to guess, they might go with Mecca the way Jews did with Jerusalem. Or they might go with local solar time.
Now we have the week. this gets *really* problematic, because it's supposed to be important to take a *specific* day of the week as a day of rest. No putting it off or doing it early. It has to be *that* day.
Now, using Mars as an example, from my previous post, we know that 36 Martian sols is a bit over 37 days. Which means that you'd be taking that day of rest a day late! Not good.
Trying to stick with the earth-based week for this will be a pain. And various religious authorities *will* Have Opinions On This.
Beyond the week we've got months and various holy days (holidays) based on the year.
( Read more... )
Entry tags:
How to tell time
Moving off earth means a lot of things change. And if we not only get off earth, but manage to colonize other star systems, they change a lot.
On Earth we have our "simple" 24 hour clock, with 60 minute hours and 60 second minutes.
Those numbers are actually a lot better than most folks think. 24 is evenly divisible by 2, 3, 4, 6, 8 and 12. That makes it easy to split things up for shifts and the like. The sometimes suggested "decimal time" only lets you divide the day into 2 or 5 chunk without dealing with odd fractions.
And 60 is divisible by 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30.
So a standard day will likely remain 24 hours/ 1440 minutes/ 86,400 seconds.
Now, on Mars or some hypothetical planet around another star the length of the "solar day" is going to be different. And it's important to not get the local day and the standard day confused.
I'm going to assume that we will follow the lead of the folks monitoring the various Mars landers and use sol for the local solar day.
We will want to divide the sol into useful periods. And do some *evenly*.
Why? consider colonists on Mars. The sol is an important unit, because many/most outdoor activities are going to depend on sunlight.
One commonly seen proposal is that we just keep hours, minutes, etc. That's kind of doable, but a royal pain.
Consider Mars. A mean Martian solar day, or "sol", is 24 hours, 39 minutes, and 35.244 seconds.
The guys on graveyard shift are not gonna appreciate having that extra 40 minutes in their shift.
And once you have more than one base on the planet (unless they are very close to each other, you have to deal with timezones. So that make the extra "40" minutes happen at different times of day depending on your longitude. Ick. That make things worse.
( Read more... )
On Earth we have our "simple" 24 hour clock, with 60 minute hours and 60 second minutes.
Those numbers are actually a lot better than most folks think. 24 is evenly divisible by 2, 3, 4, 6, 8 and 12. That makes it easy to split things up for shifts and the like. The sometimes suggested "decimal time" only lets you divide the day into 2 or 5 chunk without dealing with odd fractions.
And 60 is divisible by 2, 3, 4, 5, 6, 10, 12, 15, 20 and 30.
So a standard day will likely remain 24 hours/ 1440 minutes/ 86,400 seconds.
Now, on Mars or some hypothetical planet around another star the length of the "solar day" is going to be different. And it's important to not get the local day and the standard day confused.
I'm going to assume that we will follow the lead of the folks monitoring the various Mars landers and use sol for the local solar day.
We will want to divide the sol into useful periods. And do some *evenly*.
Why? consider colonists on Mars. The sol is an important unit, because many/most outdoor activities are going to depend on sunlight.
One commonly seen proposal is that we just keep hours, minutes, etc. That's kind of doable, but a royal pain.
Consider Mars. A mean Martian solar day, or "sol", is 24 hours, 39 minutes, and 35.244 seconds.
The guys on graveyard shift are not gonna appreciate having that extra 40 minutes in their shift.
And once you have more than one base on the planet (unless they are very close to each other, you have to deal with timezones. So that make the extra "40" minutes happen at different times of day depending on your longitude. Ick. That make things worse.
( Read more... )