I would like to know the position and orientation of the Earth, relative to the sun, as a function of time.
I.e. select any coordinate system with the Sun at the origin so that the earth lies in the x-y coordinate plane. Provide a function which takes as input the time and produces
- The x-y position of the center of the Earth
- The unit vector from the center of the Earth to the North Pole.
- The orientation of the Earth around this vector
This function is chaotic in general. I would be happy with a decent approximation.
This problem is solved as part of the "what is the position of the sun in the sky" problem. Solutions to this problem tend not to be well separable (at least I have trouble separating my question out of the complete position-of-sun-in-sky solution.)