How to explain this trajectory of the moon taken from the same spot on Earth over 28 days? Found this picture online, was wondering why the trajectory has taken such a beautiful shape ?
This is a digitally enhanced composite set of images of the Moon, with successive images taken 24 hours and 40 minutes apart. There's also a long gap in time between the left half and right half of the composite. The creator of the photograph took artistic license to enlarge the Moon; she thought that that made the composite image look better. Images of the new Moon / nearly new Moon are also enhanced.
Had consecutive images been taken 24 hours and 51 minutes apart the resulting composite would form a more or less closed curve. Successive images were instead taken 24 hours and 40 minutes apart so as to intentionally create a non-closed curve. The first image is at the top right while the last image is at bottom left.