Sunpath

[Joerg]

As per Alex' request, here's a separate threat for discussing the Sunpath and associated phenomena.

 

16 minutes ago, Alex said:

1 hour ago, Joerg said:

Your quote made me realize that I meant an equatorial position at the solstices, not the equinoxes.

Actually, I think you were right about this the first time!  

Ok, I see I need to clarify. At the Gloranthan equinoxes, the Sky Dome tilt ought to be zero, so Pole Star and Yelm (at noon) ought to stand directly above the observer. Wherever on the Gloranthan surface world. Away from the Gloranthan equinoxes, the maximum deviation of Pole Star and the Sunpath ought to be within the variation an observer on our Earth's equator would see between solstices.

16 minutes ago, Alex said:

1 hour ago, Joerg said:

And yes, except for the seasonal variations in day length, Glorantha is a tropical setting when it comes to the course of the sun. Which means fairly short periods of dusk and pre-dawn half-light, and none of that "never quite dark around midsummer" nonsense you get north of 50°. (Not to mention craziness like the arctic midnight sun). Almost as weird as the Sunstop situation you get on Ringworld.

While I think that for all the obvious lozengey reasons day length is indeed invariant across the entire surface world, I'd be inclined to salvage a little bit of RW flavour by having twilight length depend strongly on both "latitude" and day of the year.  Obviously north of the arctic circle is the equivalent of the Heroplane, though!

Such a latitude effect doesn't seem to be canonical.

Unless you have a different flow of time in the Outer World (along with a different scale in terms of distances and size of inhabitants), I don't quite see how this could be achieved. Kalikos, the Midnight jumper, might be able to illuminate the Glacier from within, but that would be unappropriately just at the time when the night should be darkest, rather than at dusk and dawn. Theya and Rausa don't have any northerly preference, and a longer northerly day might mean that you miss more of either of these Sunpath jumpers.

I guess I prefer a constant Mastakos/Uleria to Lightfore speed rate all over Glorantha on any given night, and not constant over subsequent nights, with Mastakos/Uleria making between one and two of their sky dome cycles depending on the season. One-and-a-half cycles on the equinoxes, which still leaves the question of the hours at which the set/rise effect happens. Dendara/Entekos/Moskalf and Lokarnos are too sluggish to observe much of a daily progress in the sky.

 

The most interesting thing the sun can do in the extreme north is hide behind the Red Moon. I doubt this happens every day in Altinela, but depending on how distances change in the Outer World, possibly south or north of the city, with perhaps one day in the year (either solstice) having the shadow touch the city in the afternoon.

 

 

[Alex]

8 hours ago, Joerg said:

Ok, I see I need to clarify. At the Gloranthan equinoxes, the Sky Dome tilt ought to be zero, so Pole Star and Yelm (at noon) ought to stand directly above the observer. Wherever on the Gloranthan surface world. Away from the Gloranthan equinoxes, the maximum deviation of Pole Star and the Sunpath ought to be within the variation an observer on our Earth's equator would see between solstices.

I would agree with all of the above.  One additional possibility I'd moot is that the sun and the Sky Dome might tilt in phase, but different total amounts.  So you'd see them bang in line at the equinoxes, but less and less so in the summer and winter.  This would have the merit of allowing something closer to the RW amount of seasonal variation in the sun's path, without the entire sky lurching drunkenly over to the same extent.  (Just mild tipsiness, really.)  Also makes conjunctions of Sky Dome objects and Sunpath planets more complex/interesting.

7 hours ago, Joerg said:

Such a latitude effect doesn't seem to be canonical.

Certainly not.  But is it canonically wrong, or merely unspecified?

It would essentially just imply that twilight isn't strictly a celestialogical phenomenon, but is within the domain of the Lower Sky.  Which doesn't seem to me inherently unreasonable, as such.  Yelmalio forced to slum it with the plebs...

7 hours ago, Joerg said:

Theya and Rausa don't have any northerly preference, and a longer northerly day might mean that you miss more of either of these Sunpath jumpers.

Again, I'm not proposing any variation in the length of day, as such (i.e. sunrise (and Lightforeset) to sunset (and Lightforerise)).  That would remain an Upper Sky effect, unaffected by such terrestrial sullying where one happens to be in Glorantha.  It'd be perfectly possible to see bright celestial objects during twilight -- just as one's often able to see Venus in the RW sky, regardless of fairly significant brightness remaining in the sky.  (Also true of some of the brightest stars, though none are are bright as Venus, so to a lesser extent.)

7 hours ago, Joerg said:

I guess I prefer a constant Mastakos/Uleria to Lightfore speed rate all over Glorantha on any given night, and not constant over subsequent nights, with Mastakos/Uleria making between one and two of their sky dome cycles depending on the season. One-and-a-half cycles on the equinoxes, which still leaves the question of the hours at which the set/rise effect happens.

I don't know, and I share your curiosity as to whether the Guide's illo is schematic or observationally precise (and to what degree).  It's not impossible that the artist is working from art direction based on a Greg sketch based on an Ephemeris freezeframe based on...  no actual original data in particular.  (Other than "well, it has to rise sometime...")  I would certainly also share your assumption it's the same everywhere in Glorantha:  i.e. it's an "infinitely distant" object on the Sky Dome per se.  Not a mundane rock hurtling through the upper atmosphere (or a weird hybrid of the two, like the Red Moon).  Whether it's constant I don't know, but if it's not, that's increasing the number of unknown unknowns, in terms of its behavioural parameters.

7 hours ago, Joerg said:

The most interesting thing the sun can do in the extreme north is hide behind the Red Moon. I doubt this happens every day in Altinela, but depending on how distances change in the Outer World, possibly south or north of the city, with perhaps one day in the year (either solstice) having the shadow touch the city in the afternoon.

It's one of the ongoing headscratchers to me that when Glorantha has a central and indeed near-universal myth that has the obvious celestial interpretation "sun gets eclipsed by strange combination of moons", there's seemingly no way this can actually ever happen in the mundane world.

[David Scott]

Here's the link to the Glorantha Ephemeris which may be of interest and help to those reading this topic. @Alex was one of the contributors to it.

http://www.glorantha.com/docs/new-myth-month-moveable-ephemeris-and-gloranthan-sky/

[Joerg]

16 hours ago, Alex said:

I would agree with all of the above.  One additional possibility I'd moot is that the sun and the Sky Dome might tilt in phase, but different total amounts.  So you'd see them bang in line at the equinoxes, but less and less so in the summer and winter.  This would have the merit of allowing something closer to the RW amount of seasonal variation in the sun's path, without the entire sky lurching drunkenly over to the same extent.  (Just mild tipsiness, really.)  Also makes conjunctions of Sky Dome objects and Sunpath planets more complex/interesting.

Yelm avoiding the celestial city would create certain upset, don't you think? If he gets out of sync with Polaris too much, Lightfore's re-creation of the Yelm the Youth myths in the night sky would be quite off.

16 hours ago, Alex said:

Certainly not.  But is it canonically wrong, or merely unspecified?

Depends on how you want to accomplish the different effects.

16 hours ago, Alex said:

It would essentially just imply that twilight isn't strictly a celestialogical phenomenon, but is within the domain of the Lower Sky.  Which doesn't seem to me inherently unreasonable, as such.  Yelmalio forced to slum it with the plebs...

Interesting. A deity of atmospheric light... but somehow tied to the north of Glorantha (unless you suggest a southern arctic effect despite the fact that the south is the source of heat and fire), and present after dusk and before dawn, though disappearing at midnight. At a time when the Sky Dome and the Sunpath veer south (and it veers further south than north, or the skyspill would have hit the north rather than the south).

16 hours ago, Alex said:

Again, I'm not proposing any variation in the length of day, as such (i.e. sunrise (and Lightforeset) to sunset (and Lightforerise)).  That would remain an Upper Sky effect, unaffected by such terrestrial sullying where one happens to be in Glorantha.  It'd be perfectly possible to see bright celestial objects during twilight -- just as one's often able to see Venus in the RW sky, regardless of fairly significant brightness remaining in the sky.  (Also true of some of the brightest stars, though none are are bright as Venus, so to a lesser extent.)

Aren't those dusk or dawn effects? We might see Venus around sunset/sunrise, but I haven't seen the second brightest object in the sky around that time, yet (and that's the ISS, which admittedly is best seen when opposite of the sun).

16 hours ago, Alex said:

I don't know, and I share your curiosity as to whether the Guide's illo is schematic or observationally precise (and to what degree).  It's not impossible that the artist is working from art direction based on a Greg sketch based on an Ephemeris freezeframe based on...  no actual original data in particular.  (Other than "well, it has to rise sometime...")  

The celestial precision clock, based on Mastakos/Uleria. Even if the period isn't exactly 8 hours.

16 hours ago, Alex said:

It's one of the ongoing headscratchers to me that when Glorantha has a central and indeed near-universal myth that has the obvious celestial interpretation "sun gets eclipsed by strange combination of moons", there's seemingly no way this can actually ever happen in the mundane world.

Funny you should say that. Artia the Bat is among the rebel gods that lead to the demise of the Emperor, as is Tolat. Artia has been called a moon at times, and Tolat's star is also called "Little Moon" when it isn't called "Bronze Treasure".

[Alex]

On 02/07/2016 at 10:51 AM, David Scott said:

Here's the link to the Glorantha Ephemeris which may be of interest and help to those reading this topic. @Alex was one of the contributors to it.

http://www.glorantha.com/docs/new-myth-month-moveable-ephemeris-and-gloranthan-sky/

Thanks, that's a help to me, I think, as it spares me trying to find a copy on dodgy HDs from several computers ago.  Ironically, I can't run it right now, at least on this here Chromebook, due to Google's War on Java.  It'd be true to say that while Mr Tines did most of the heavy lifting of the initial coding of this, I'd my paws on the various parameters last, which if nothing else qualifies me to say how sketchy some of the guesses at what they ought to be.  (Some of the more uncertain there's "wizard mode" controls for, but in some others there's just provisional guesses hard-coded in.)  Of course, some of them might have been canonicalised (or possibly negated) by subsequent decisions elsewhere.  At any rate, in many cases "goes to evidence of state of mind", insofar as I'm even remembering it correctly.  Please do keep me right on both aspects, all.

Edited July 5, 2016 by Alex

[jajagappa]

57 minutes ago, Alex said:

this here Chromebook, due to Google's War on Java

I found I had to take two steps to get the Ephemeris enabled on Chrome.

1) Look through the instructions here to enable/fix Flash problems in Chrome to enable PPAPI.

https://support.google.com/chrome/answer/6213033

2) Update the Exception list for Java

https://www.java.com/en/download/help/win_controlpanel.xml

You will need to add the following to the Exception Site list under the Java Control Panel>Security tab:

http://www.glorantha.com/site-apps/ephemeris/EphemerisII.html

 

[Alex]

2 minutes ago, jajagappa said:

I found I had to take two steps to get the Ephemeris enabled on Chrome.

Apparently Chrome*OS* is more vexatious still, though.  But I should be able to run something via crouton/Ubuntu, or if all else fails, find a Steampunk relic from a bygone age that should be able to run it.

[David Scott]

so how about updating it to something thats not so problematic - HTML5, Javascript?

(not me I'm just poking)