How can the sky jump in rotation if it is really the earth and observer spinning? This suggests that the sky is rotating and not the earth.
This adresses a problem with simulating a movement of the observer and it has nothing to do with real events or the model. The problem is related to the radial coordinate system used. It is independend of flat or round earth.
It happens if the programmer does not put effort on handling the movement across or nearby the pole.
Assume the observer is moving to north and also looking to north. When he crosses the pole north is in the oposite direction, which leads to a 180° turn of the observer.
I assume it has not been fixed yet because it is reasonable effort and just a "cosmetic" problem. The sky shown is correct but the U-turn might irritate the user.
Again, seems to suggest that the celestial objects are being brought into position for the geocentric observer.
This observation is absolutely correct. But don't mix up "geocentric observer" which means that the perspective is taken from location on earth with "geocentric model".
The position of the objects in a 3D space are calculated based on heliocentric model. For 2D visualization this 3D objects are projected to 2D. To do so it is necessary to rotate the objects according to the observers orientation in space - but only if RET model is used. Therefor I put it here as evidence.
In the meanwhile I found out that the documentation is a better reference than the code (right, I could have had this idea earlier).
IMO, Stellarium is not based on the RE system specifically, but is based on geocentric and celestial sphere concepts.0
Maybe you give the user documentation a read to verify your assumptions. PDF can be found on stellarium.org homepage.
Here some quotes:
"The apparent movement of the stars is due to the rotation of the Earth" => RET
"Stellarium uses the VSOP87 theory" which is heliocentric
You probably will find the word "geocentric" in the document but only in the context of "geocentric observation" which is not equal to "geocentric model".
AFAIK initial intention of Stelliarum was to simulate and support (telescope control) earth bound observations.
However Stellarium supports also space travel and observer on other planets in the solar system.
Example:
So whoever wants to state an opinion to the initial question should consider:
- Stellarium is based on RET Math (btw. I would be interested in formulas to calculate the position of celestial objects at given time & location without using RET which I have not found yet)
- Space travels and observation of the solar system from "outside" are possible
I think 42’s question was simply whether you would accept output data from Stellarium as being accurate for the purposes of debate.
Thanks for this Bob!
Maybe it was a mistake to add the RET hint to the initial question, but I wanted not to surprise someone later.