I'm a robotics researcher writing orienteering code for a solar-powered lunar rover. I have two similar problems:
Given the position of a robot on the moon in lunar latitude/longitude, where is the sun? That is, which direction should I orient my solar panel to maximize incidence?
For testing purposes, I need to solve the same problem on Earth. Given Earth lat/lon, where is the sun?
To be honest, I'm not even sure what coordinate system to use to express the answer to these questions. I was considering a coordinate frame centered on the rover with East, North, and Up axes, but I'm open to a better suggestion!
So far, I've found some information about VSOP87 and ELP2000, and I've started reading "Astronomical Algorithms", but I'd appreciate help from the experts.
Here's what I've got so far. I can get the coordinates of the Earth-Moon barycenter using VSOP2013. If I can get from the barycenter to the center of the Earth, I can probably use EPS2000/82 to find the position of the Moon in heliocentric coordinates.
At very least, I think this would get me the moon coordinates in the sun frame. I'm hoping it would also give me the orientation of the Moon in the sun frame?