Virgin Mary painting and the controversial background

There is a painting of the Virgin Mary that contained controversial background. Located in a tapestry from medieval times is in the Collegiale Notre Dame, Beaune, France called "The Madonna with Saint Giovannino". Can you identify what is in the background in the upper right? UFOlogist believed it is a flying saucer or UFO.

Above Mary's left shoulder is a shining, or glowing, disk shaped object. A man and his dog can clearly be seen looking up at the floating object in the composite below. Painted in the 15th century, Palazzo Vecchio lists the artist as unknown, although attributed to the Lippi school.

Upon closer inspection, the man seems to be looking away from the UFO, behind him and over his shoulder. Or, more likely, the notably out of place object may be imagined floating above the ground between them. Also, Mary's halo seems a bit shadowy, it is not a ring of light but rather like a vortex where this UFO shaped came from.

Until now no one can really explained why or what is that object. The question of the many including researchers and scholars remained unanswered as to what the painter want to express or its point of view of depicting unusual shape in its masterpiece.

Or, is it a fact that these UFO have been in operation for many thousands of years. We still do not know what they are, Where they came from or who they are.