There are two sorts: (a) between the moon and the horizon, which is a typical planet sight, and (b) a 'lunar sight' which is between the moon and another planet (like Venus). This is a difficult sight to take accurately BUT is the only sight you can take where you can get your position without knowing the time (if you have the proper tables). I don't think the paper tables exist for it any more but it is built into a few of the nav calculators/computer programs. I have tried it but it is difficult for three reasons, both the objects are moving pretty quickly (no fixed reference like the horizon) and you are usually point the sextant up in the sky at an odd angle, and there is no way to 'rock' the sextant to check you have the alignment correct like you can with the horizon.