A body is orbiting the sun and rotates about its axis (z). My coordinate system is co-rotating with the body. I need to determine how does a vector that points to the sun change after a certain period of time. Initially the sun vector lies in the xz plane. Basically I need to find the rotation matrix that I can apply to the vector. I have been googling for over a day without any result. Can you point me to an article or book with a good explanation and derivation or explain how this is done? Thank you.