Haoes 9those gold circles around the heads of jesus, mary, the apostles, etc.) started showing up in medieval paintings…possibly as early as AD 900. I’ve laways been puzzled by htese…does the Bible talk about them? Anyway, what do haloes do? Obviously, they are only worn by very holy people…how does one go about getting one? And, when did modern artists drop them from portrayals?
What do the protestants say about haloes? 
Well, mine has never been a problem…
It’s an iconic representation of holiness, deriving from the Shekinah glory attributed to God, which in some O.T. theophanies is reported to illuminate Him. They originate in Byzantine art.
Symbolize holiness. Period. You don’t take one off and play Frisbee with it, or something.
Instructions for getting one are given in Matthew 5:48. 
It’s not those artists’ symbolism, so they don’t use them. (Modern iconographers still depict haloes, BTW – it’s not like somebody forbade them.)
I haven’t known any direct Protestant comments about them. Protestants tend to avoid discussing saints, as a general rule, except in some cases for the apostles. Presumably as a symbol of holiness, they’d be acceptable in Protestant art using traditional iconography.
The Master speaks: http://www.straightdope.com/classics/a1_040.html
This thread is better suited for GQ.
I’ll move it for you.
Cajun Man
for the SDMB
Haloes appear in Buddhist art as well, and I’m not sure who had i earlier. Australian rock art also shows haloes around the heads of supernatural creatures.
I’ve long suspected that haloes are ultimately due to optical phenomena. You can see approximately circular blazes of light around the shadow of your head in a number of circumstances – particularly when it’s thrown on a dew-covered lawn (the resulting phenomenon s called "heiligenschein’), or when your shadow is thrown on a cloudbank or fogbank. In this ase the phenomenon is called a “glory”, and it assumes the form of a series of tight rainbow-colored bans around your shadow. If you’re up there with other people, you’ll only see the glory around your own head (since it results from interference between beams of light vry nearly retroreflcted from tiny drops of water). In other words, everyone sees themselves as “holy”, but not their companions. (I usually see a glory around the shadow of my plane when I fly over clouds, and am on the correc side of the plane to see he shadow). In this regard, I note that some haloes are rainbow-colored as well.
The sharp outlne of the circular halo was a stylization that continued to evolve, so that eventually the halo was represented as a floating golden hoop over the saint’s head, a convention that really doesn’t make a lot of sense. lus, it gave us all those dumb Christmas pageants where kids wear bent-into-shape coat hangers on their necks covered with auminum foil to look like that kind of halo.
By the way, for pictures of these effects aong with explanations, see M. Minnaert’s classic book The Nature of Light and Color in the Open Air.
Tyhe Bible does mention haloes or something very similar to haloes in several places. The Earliest reference I can think of is Exodus 34:
29Moses came down from Mount Sinai. He had the two tablets of the covenant in his hands. His face was shining because he had spoken with the Lord. But he didn’t realize it. 30Aaron and all of the people of Israel saw Moses. His face was shining. So they were afraid to come near him.
31But Moses called out to them. So Aaron and all of the leaders of the community came to him. And Moses spoke to them. 32After that, all of the people came near him. And he gave them all of the commands the Lord had given him on Mount Sinai.
33Moses finished speaking to them. Then he put a veil over his face. 34But when he would go to speak with the Lord, he would remove the veil. He would keep it off until he came out. Then he would tell the people what the Lord had commanded. 35They would see that his face was shining. So Moses would put the veil back over his face. He would keep it on until he went in again to speak with the Lord.
We see something similar in Acts 2:
3 They saw something that looked like tongues of fire. The flames separated and settled on each of them. 4All of them were filled with the Holy Spirit. They began to speak in languages they had not known before. The Spirit gave them the ability to do this.
I just want to tweak this by reminding readers about polygonal haloes, as mentioned by The Master Hisself.
On first read I pictured Mick Jagger with a halo standing by a kangaroo, but further contemplation has cleared away that unsightly image.