Sometimes you just need a healthy dose of good ol' exposition, and when that time comes a character like Stunt works well in a magical dilemma. He's the "fish out of water" and needs things explained to him. If I've done my job right (and I hope I did), then the explanation doesn't feel clunky or too exposition-y.
That, and I thought it was a good way to showcase that most of what is currently known to humans about the Heart of Magic is theory and belief, while the exiles of Old Eldariat speak about its properties with much more confidence.
This isn't the first time astronomical phenomena have mirrored magical and otherworldly properties around here. Besides, I think some of the best tales of magic have planets and stars aligning and such, so I figured giving the elusive source of magic a grand orbit would be neat, too!
That's all from me for now.