Although reports differ, most observers describe the phenomenon as a small white sphere on the horizon that expands uniformly outward and upward while maintaining its dome-like shape. It is initially opaque, but as it expands it becomes transparent, and the stars can be seen through the center of the dome. As it begins to fade, the outer boundary remains brighter forming a rainbow-shaped arc. At full extent it has been reported as being tremendously large, filling more than half of the sky. Approximate calculations (redacted) indicate is is on the order of 1 ... Read even more
