Does Mercury look like he’s rotating clockwise or anti-clockwise?  That may depend on whether you look at the left hand figure, or the silhouette.  That right hand silhouette figure can appear to rotate either way round.  Some viewers find that it flips from clockwise to anti-clockwise spontaneously, but others may find it hard to make it flip from one rotation to the other at all.  If it doesn’t change easily for you, try waiting till the outstretched arm is pointing top left, and then try to imagine the hand coming towards you (for an anti-clockwise turn) or moving away from you (for a clockwise one).

When the silhouette figure turns clockwise, it’s rotation mirrors the red figure.  When it flips anti-clockwise, the two figures appear to go round the same way, but with the silhouette figure rotating half a turn out of sync with the red figure. I find the change fascinating, like the figures are doing some kind of old style dance, but two different ways.

The rotation of the right hand figure is ambiguous because in silhouette it presents exactly the same image whichever way it turns. Add the reflections and shadows of the red figure and it can only be going one way around.

I made the individual frames for the animation by taking successive still photos all around a reproduction of the original sculpture.  (The original was made by Italian sculptor Giambologna just over four hundred years ago, and is in a museum called the Bargello in Florence, Italy).