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Then we have to decide what "realistic" is.

I don't think we can "fix" the sun/moon -- all the shadows in Atys depend on it being stationary. On the other hand a tetrahedron of "suns" fixed around Atys (to keep all parts illuminated) would be a super-scientific feat, so that wouldn't be bad. That would give us an
East Pole. (for the sun we can see).

It would help if the stars moved in a "real" (i.e. fixed sources given motion by the rotation of the planet) way.

The stars and nebula seem to rise in SE sky and set in NW, indicating that the axis of rotation is NE-SW- about 40-50 degrees from the magnetic north.

Placio --

First of all, you need to check out the rising and setting of the nebula in different places. If you compare FH and Void, the nebula does not rise in the same place in the two locations. Near Paramount stock, it rises about 15 degrees East of South. In FH it rises about 50-60 degrees East of South.

The nebula moves relative to the stars. Slowly, but it does move.

The stars do not rotate as a fixed group of objects. They flow. I have looked for a pole (I.e. a place where the stars do not move or move around in a small circle, and have been unable to find one.

Thanks again for reminding me that you have already surveyed some of these objects. I am aware that they are at different angles depending on the observer's location. Another complication is that we have no measurement of altitude on atys- the jungle could be km higher or lower than the lakes- In the desert specifically the Ringed planet seems to rise higher than in the lakes, even after considering the walls blocking the horizon. I think if the observer is at a lower altitude the ringed planet should appear to be higher in the sky? same for the "sun" i think.

You're right, there is no polar area visible, but it is very easy to infer which direction it would be. I'm not sure if it is always under the horizon or behind another obstacle or even if Atys is a shape other than the sphere that our client icon indicates. If Atys were more cylindrical than spherical we would not be able to see much of the polar stars. The wobble that was suggested as an explaination for the behavior of the ringed planet could also explain why we don't see the traditional set of polar stars that rotate around a specific point.

We've established that the sky as currently animated does not comply with a "newtonian" system as you would say and moved on to hypothetical situations based on the observations that do make sense. The location of the axis is based on what I can see and yes is a hypothetical- we've already said that whats in the sky basically cannot be real for various reasons, so no, I cannot point to the North star of Atys- but if the stars go from SE to NW then the Axis is somewhere near NE-SW.

Lordoy, kami'ata, deles silam, oren pyr.
Gentles of the Atysian Sky Observer Club --

After several very long sessions of observing the night sky on clear nights near Oflovak's Oasis and making very careful lumios at short intervals, I was able to trace stars and groups of stars across the heavens from dusk until dawn.

I veryified that in fact the stars seem to rise in the SE and set in the NW (although not precisely). Therefore, if the stars are set on a sphere above Atys, as proposed by my friend Placio, and since they seem to rotate as a unit (at least to first impression), then as any child in the New Lands knows, if you rotate a ball, then there must be two points (stillspots) that do not move, and around which the nearby surface of the ball makes small circles as it rotates.

It is also self-evident that if there is a pattern drawn on the surface of the ball that it remains the same as the ball rotates, and the same would be true if a homin were very small and viewing from the inside of a transparent ball made, perhaps, of oiled cloth.

If we assume as Placio does, that the stars are on such a sphere, and that the sphere turns around us [1], then we should be able to see such a motionless point, or if it is too close to the horizon, then at least see the circular arcs that the stars make.

And if we are at the center of the ball, then if one stillspot is below the horizon, the other must be above the horizon by the same amount, since they are opposite each other on the ball.

It was these observations that I tested in the desert. I present to you my composite views of the motion of several groups of stars across the sky viewed both to the southwest and to the northeast. In each case I have marked out some star patterns either with dots or with lines representing the distance and direction between two stars.

It is immediately clear from my observations that not only is there no stillspot to be observed in either direction, but that while small patterns are stable, the relationship between patterns that are separated by any distance changes during the hours of the night. In addition, the stars do not move in a circular arc near the horizon, at least not a small circular arc.

Observations:

Viewed to the southwest (motion of stars is to the right):



Viewed to the northeast (motion of stars is to the left). The hook shapes are a fragment of a circular arc of stars.



Viewed to the north and a little bit east (motion of stars is to the left): Note the reduction in length of the "vertical" separation of the stars.



Conclusions:

The stars are not fixed to their ball. The ball of the stars does not turn with Atys at the center. Therefore the stars must be put in place by the Powers to test the faith of their followers, or they are just some phenomenon of the atmosphere.

My next area of study will be the ringed object and the orange object. [2]

Respectfully submitted,
Bitttymacod
Research Fellow
New Trykoth Council of Scientists.

[OOC
[1] This is geometrically equivalent to Atys rotating within a view of a pattern of fixed stars far distant from the surface. Note that this does not rely on the shape of Atys itself, only the assumption that the stars are fixed and distant.
[2] The obvious conclusion is that the devs were really f-ing sloppy in designing the sky.
/OOC]

OOC
It can be done technically ive looked at some of the various models including the sky box and objects in there. There are orbiting models for various things. Now it cold be that over the years they have made small changes to the various elements or removed animation to bump performance etc

Once i get these max import/export plugins and tools figured out ill play with stuff on my end see what i can come up with and send along to the devs and see what they think.

Technically speaking each zone of ryzom is a flat plane with a height field map that gives us our terrain with various objects added (buildings trees etc) Other objects are in the air above this plane the limbs of the canopy for example. Something that would be possible for the sun moon/s stars and planets is animated objects that rotate around these zones going above and below the plane. This would give us sunrises and sunsets. Having the sun moon etc as light sources could change (potentially) shadow directions and lengths. 3d studio max has this ability but i do not know if the nel engine etc does i suspect it does.

So giving us a very realistic sky is quite doable and it is all open source so if you have 3d studio max and the tools for ryzom core i say go for it see what you can do. im going to fool around with it all my self but my times fairly limited so how much i can do i do not know.

OOC: nice job! I did years ago a sky with star, sun and 2 moons with Blender, so I think it is possible today to make a "realistic" sky. Can somebody expose the idea to the team of Ryzom?

[ooc]
Personally I wouldn't mind if the rest of the sky became more "realistic", but I'd really like to keep the fixed "sun" (collection of fixed suns). I like the flaring and calming of the object, and the fact that it is obviously artificial (since the seasons must be due to programmed increases and decreases of the total output of the sun.) I think it adds an element of the exotic and inexplicable to the environment.
[/ooc]

It is a game- so I don't expect it to be 100% accurate, but the origin of this discussion was to possibly learn or infer more about Atys or other Ryzom things.

Because we obviously have an artificial light instead of a sun I would propose a couple ideas:

1. Atys does not orbit a star, the star does not emit sufficient usable light, or the orbit of Atys is very far from the star of this system.

2. Assuming that the artificial light is a technological structure (most likely in this case) it suggests the Karavan/MegaCorp have access to fusion. Its the only energy source in our current understanding of physics that would be able to produce energy comparable to a stars' power- because it is actually where star get their power from. But if they have fusion, why the heck did they bother with Atys? They could just take materials from Atys or the ringed planet or the orange moon and create a giant rotating habitat or floating city on the ringed world.

Yes, most of this is OOC. I am RP friendly but this is not solely a RP thread :)

Third possibility, Atys orbits a star but is tidally locked and we are not on the side facing the star. (This would mean that any "realistic" Stars would have a motion that was linked to the year, not to a day.
We might even be in a Trojan position defined by the ringed object and the star.

You are *assuming* that the sun is technological. It might also be magical. Even if it is technological, placed there by the Karavan, and based on fusion, that does not imply easy transmutation of the elements. Remember, we don't really know the Karavan's agenda, and we only have the word of the Kami that the Karavan are here to strip-mine Atys.

By the way, we know that when we look at what is apparently a solid object in the sky (at night after the flares die down) we see something that looks about like the Moon does in the skies of Earth. If we assume an angular diameter of 0.5 degrees (Moon from Earth), and a distance of 250km (midway in my estimates), the diameter of the physical object is only 2 kilometers! That's not nearly big enough to support fusion, though it might be big enough to be a radiator for a fusion reactor. Note that it is also *much* smaller than Atys, which extends at least 35 km without significant deviation from planarity in the New Lands. ((There is not enough information to say from ingame measurements whether or not the New Lands are on a large sphere or on a large plane. -- in computer game space, of course, they are on a plane.))

In-game, given the information on which I based my True Map, and assuming that there is a possibility of 5% error (assumption for the purposes of demonstration -- my actual error in lining things up is less than 1%) that might show curvature of the surface, the *minimum* diameter of Atys is 220 km. Much more likely, given that it has an atmosphere, is > 8,000 km. ((Of course the atmosphere could be held in by technological or magical means, but unless we have a substantial diameter the gravitational constant would be very low. I think we can discount artificial gravity applied on a planetary scale.))

The only way we would never see any trace of the star is if we were tidally locked to the star itself. A moon or asteroid that is tidally locked to a planet will still complete exactly one rotation per one revolution of its planet- The dark side of earth's moon gets the same amount of light as the light side, except it is a new moon when the far side is getting direct sunlight.

Yes, I think the L1 point is a likely place for Atys. Otherwise, since we appear to be so close to a larger ringed planet I would expect atys to be captured as a satellite, collide with the planet, or be otherwise flung from the larger planet's path :( Based on the current sky animation, there is no evidence that we orbit the ringed planet- and that planet's appearance near our magnetic north pole could just be coincidence, rather than tidal locking (which I don't think occurs with trojans since they are at a point where the planet's and star's gravity negate each other).

Placio -- Yes, I meant -- tidally locked to the star, not to a planet.

In the Trojan position, it would take very little effort (comparatively speaking) to stabilize the planet, and the motion of the ringed object could be some sort of librational motion (which would be emphasized due to the fact that we wouldn't have the high angular momentum to keep the pole in place.

I love this post/thread. I have often in the back of my head wanted to start studying the stars and planets around Atys when I got time, but have been busy lately. I am so happy this club or association has started, May I join?

I have no idea how to determine things such as in your discussion. I have often wondered how astronomers through ancient history have discovered things like if (OC: the sun revolved around the Earth, or visa versa. How a dot in the sky is either a sun or a planet, and the time it takes to go around the Sun, and things like these.) It takes real time and thinking I guess.
I guess i will have to use my brain and try to contribute. In the mean time, I look forward to more discussions on this subject.

-Thanks for starting this discussion!

~Naema

Welcome Naema! Everyone is welcome :) We just need to take what we can observe, offer possible solutions, and then see which solution would fit best. And we can only decide on a best fit, since the animation of the sky is not that scientifically accurate.

But..... It's MAGIC!!!!

Just saying....