The Orion's Arm Universe Project Forums

Moonbow by Rick Sternbach:

That's nice! It resembles the Hoopworld which I described in the Oracle War article, and the Hoopworld was itself based on some calculations by Grant Hutchison which were intended to describe a toroidal planet with the same rotational period as the Earth. Grant has noted that a Hoopworld would be less stable than a donut world like Torus, and would quite quickly separate out into spherical globules.

But presumably both the Terragen Archai and whoever built this Moonbow have a remedy for that problem.