Hi, I have noticed lately that the position of the moon seems to move during the course of 24 hours. I always thought that the moon stayed in the same position with a north pole and a south pole but now it moves hourly tilting up to 90 degrees to the right and then to the left. Did anyone else notice this or am I wrong?
If you're looking through a telescope using a star diagonal the orientation can seem to vary considerably simply by twisting the diagonal.
The north & south poles of the moon are not marked by any particularly obvious features. The obvious features for orientation are the points where the terminator meets the lit limb (particularly the horns of the screscent moon). The "line" joining these is always at right angles to the "line" joining the sun to the moon ... this varies continuously as the altitude of the sun & moon is continuously changing. But you won't get "90 degrees to the right then to the left" over a period of a few hours ... in temperate latitudes ... in the tropics when the moon passes very close to the zenith you will get the rapid field rotation which is typical of altazimuth mounts whilst the observed object (whatever it is) is passing through the zenith.
The fastest rotation any part of the moon actually does is rotating as a solid body with a period of 27.321582 days (the same as its orbital period) which appears, because the orbit is not quite circular, as a slow wobble with the same period called libration ... Google this & you will find videos showing the way in which libration affects the appearance of the moon (independent of the phases) but do remember that you're seeing 27 and a bit days compressed into a few seconds.
I used to photograph moon during the nineties and the moon also had the same position ie. Tycho was always at "6 o clock" and Mare Crisium was always at "2 o clock" give or take a few degrees depending on the stage of Perigee and Apogee. But now I see Tycho moving from a "8 o clock" position to a "4 o clock" position in less than 24 hours. I have only noticed this recently and am puzzled by it. Pat45