What's the ball of light in HBO's Game of Thrones intro?

Angus Wall, Creative Director at Elastic (the company that created the intro) describes it as an "Astrolabe"

It was by and large the same people that I've worked with before, which
is nice. They were very, very supportive of what we were doing. One of
the things that came out of our conversations were the bands on the
astrolabe — they’re the bands that surround the sun. We show three
close-ups of those bands that tell the pre-history of the world in
relief-sculpture form. They tell about dragons attacking Westeros.
They tell about how the different houses on Westeros got together and
defeated those dragons, and how those houses, represented by their
respective animals, bowed in allegiance to the Baretheon stag.

You can view a concept picture here;

and the "final render" here;