I have to admit, that this is the biggest most massive halo I have ever seen. It is so big in fact that it dwarfs the tiny infant (Ihsous), and his more impressive goddess mother (See the Madonna - Isis series of photos).
Since when are small circular halos represented by "The Sun?" Just in case you are only looking at the smaller sunburst, look at the rest of the sunburst that surrounds the center one. Next look at the importance placed on the crown of the infant and the crown of Mary. Oh you might say, that is because he is just a child. Well then, why is Mary's crown so large that if it were to be set on her head it would fall to her shoulders? Have you seen "The Pieta?" Mary is still larger than the full grown Jesus (IHS or Ihsous).