Astronomers do care about this sort of thing. Over the years every time this topic comes up and the audience provides quotes from astronomical texts, we see that astronomers don't really know why, have trouble explaining it, and mumble something vague about celestial spheres.
there isn't anything to explain. you're just plain wrong that there's a problem to begin with.
https://i.imgur.com/AQpzxwI.png
you're saying that the line i've drawn won't point at the sun. i'm telling you that it absolutely does, and you can demonstrate that it does by making your own straight line with a piece of string. if you align one end of your string to be like the perpendicular line i've drawn on this moon, then you will find that the other end points at the sun.
you don't have to do any math. you say this line doesn't point at the sun. i say it does. don't take my word for it. see for yourself.
As I said, the only time the moon and sun is seen in the sky is when they are on opposite sides of the sky. Otherwise, when the moon gets too close to the sun it disappears.
A laser cannon pointed upwards into the sky is going to fire its laser beam into outer space. Its not going to wrap around to the horizon. The only way to get the laser beam to go to the opposite horizon is if you imagine it curving on the dome of the sky.
Your "string" experiment is bunk and lacking in explanatory power. You can find something pointing upwards and put a string to it and make any number of paths to the opposite horizon.
Find a panorama of the moon pointing into the sky above the sun and draw your string on it.
What you are trying to do is say that the sky is a dome and that if you make vertical triangles along the top of the image, cut it out with scissors, and paste it together in a domish way that there is a way to make (force) the moon to point at the sun. By manipulating it in this manner you can also
force the moon to point at any number of objects on that opposite horizon.
This is not coherent. It is the "celestial sphere" explanation given by some astronomers; but this explanation falls flat with the slightest breeze.
- The sun and moon are not painted on a celestial sphere around the earth where straight lines become curved.
- The sun and moon exist in regular geometric space where an arrow will always point to the object it is pointing at, not in an entirely different direction.
There will need to be a more coherent explanation than this celestial sphere theory. In RET the observers aren't in a planetarium with lines projected on a screen above them that turn into curves. The observers are in regular space.