Mystery Orb Upstages the Christmas Wreath

Photo date: December 4, 2015. Photographer: Mark Mahin.

The photo below was taken in Grand Central Terminal in New York.  Near a Christmas wreath, we see a bright blue orb.

This orb had a height that was 10 percent of the original photo height, a size that is way too big to be explained as some dust particle.  Indoor dust particles are no bigger than about 10 microns, but to block 10 percent of a camera lens (about 15000 microns in width) you would need a dust particle at least 150 microns in size (and given the sharp outer edges of this orb, meaning it cannot be right next to the camera, you would actually need a particle much bigger than 150 microns). Also, dust isn't blue-colored.