This is a pretty massive Godot endeavor. We could certainly use some love! (At the time of this post, you could still be the first to post at the forum!)
thats really a nice project you are doing here ! ... looks like a stellarium clone
There's a bunch of software planetariums out there. But nothing else you could build a game on as easily, I think... (yay Godot! )
edit: Also, Stellarium is under GNU General Public License, which means you have to use the same licence in your project if you use their code (i.e., you couldn't sell your game).