Re: Day length

From: jorganos <joe_at_1dlY5wAgOOr7h21w3YGgu3PiWMJxzKA3x-lTJfT-ae9Bq-wCUwSIpII6tmNhhJsuh5boLa-f>
Date: Fri, 04 Jan 2008 12:53:40 -0000

>> However, the Gloranthan sky has no meaningful parallax towards
>> the ground. That means if a stellar body is up 38 degrees north
>> viewed from Pamaltela, it won't be any higher viewed from 

> *Boggle* I can't quite picture that. Glorantha is small compared to
> Earth, but it's still big enough for there to be some noticeable
> differences in the sky.

A couple of years ago, Nick Brooke described the sky dome as (quoting from memory) "a perfect hemisphere 5 miles high and 10000 miles in diameter".

You see the perfect hemisphere above you. It rotates, and its rotational axis moves slightly north in summer and considerably more south in winter. The sun path crosses the axis all the time.

> For the sun to be close enough to provide useful energy, it's pretty
> much got to be close enough to be at a measurable angle away from
> directly overhead, as you move from the equator.

The sun is closer than ours, and possibly smaller (although in things divine (etc), size doesn't matter that much).

>> That doesn't seem to be the case. Both the Gates of Dawn and Dusk 
>> are so far outside of the "Circle of Time" that they appear 
>> directly east and west from anywhere within the "Circle of Time".

> That's... just downright odd.

Distances far away from Magasta's Pool (at the surface of the surrounding ocean) become subjective. My personal rule of thumb is that the original square of earth has mostly normal distances, and anything beyond behaves weirdly. The closer you get to myth (even on that square), the less important and less stable the metrics. Dragon Pass is Orlanth's kitchen if you get close enough to myth, or a castle, or the country. Depending on how close to myth (and danger) you get, the less the distances (or the greater your size - choose for yourself).

>> Sundials don't really work on Glorantha.

> I don't know; sundials are pretty much foolproof.

Assuming a constant angular speed of the sun for the entire year (or making "sun hours" subjective).

Day and night length vary over the year. In my Glorantha so much that the longest day has 16 hours and the shortest has 8 hours of sunlight only. This means that in winter, the sun hastens across the sky twice as fast as in summer, when it goes in stately procession. Vice versa, Lightfore sprints across the summer night sky as fast as Mastakos/Uleria in summer, and half as fast in winter.

>> Yelm, and in the nights
>> Lightfore, move at varying angular speed across the sky.

> Do you mean that they vary seasonally?


> Or daily?

Possible, but I won't go into that much detail - there are people who care more about celestial mechanics than I do. IMG, daily speed is assumed as constant for the casual observer.

> Longer days in Sea,
> Fire, and Earth, shorter days in Dark and Storm, and I'd expect the
> shortest day to be somewhere in Sacred Time, the period of rebirth.

Shortest day in Dark Season (hence the name), longest in Fire Season. I think there is a holy day of Yelm to mark the solstice.

> I'd always assumed that "longer days" meant longer periods of light
> relative to darkness with the overall, absolute length of time from
> noon to noon staying the same.

I think that's both canon and general consensus.

> Either way, I would think a sundial would still work for relative
> time, as long as the sun casts a shadow. You get relative time
> from a sundial, not mechanical time, so as long as you're simply
> looking for a way to break the day up into some number of
> divisions, a sundial works fine.

If you are content with 50% variation over the seasons, an ordinary sun dial will do.

> If you need regular, equal intervals, you're going to need a
> different, mechanical, timekeeper.

Or a tuneable sundial.

>>> Using some sort of orbital mechanics to explain varying day >>> lengths vastly complicates things.

>> Only if you use the sun. In a clear night, you get Mastakos/Uleria 
>> as a very reliable timepiece. Always visible, crossing the sun 
>> path in 8 hours - four hours to meet Polaris, four hours down 

> when you write "8 hours" do you mean relative time, or mechanical

Mechanical time, as the planet makes the crossing thrice a day. I have no idea at which hours it rises, though. Would be nice to know.

> I'd always assumed longer/shorter days meant longer/shorter daylight
> with the difference made up by shorter/longer nights, and overall
> duration of a day remaining constant. Are you saying the nights are
> *always* 8 hours, and the overall duration of the day changes
> seasonally?

No. Mastakos/Uleria moves across the sky regardless of day or night, at constant speed, thrice from noon to noon. Other planets are up in the sky whether visible or not, too.

Re: John Machin's question about the Midnight Sun: The land of the midnight sun would be a place outside the compromise, right? Of course, you could have a lesser sun hovering above the place. When I first read about the "triple spheres" of the Dara Happan metropoleis (in the Genertela Box), I assumed that the local deities (Raiba, Alkor) manifested as a lesser sun hovering above the greatest ziggurat of the city, day and night, just like the Red Moon hovers above the Crater, and as Yelm is said to have hovered above Yuthubars. Not sure whether that is true for the mundane view of Dara Happa, but at least to some magical sight, this ought to be reality.

Note that you can get a similar effect to the sun on the horizon from the directional jumpers, Rausa in the west, Kalikos in the north and Theya in the east. Kalikos would be responsible for the midnight illumination.            

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