OT: Ceres more interesting than previously thought

[Suicide Junkie]

Oh, and as for the radiation thing... It shouldn't take too much water to block the rads.

What if you just build a double-coin, and fill the space between them with water?

As a bonus, that water barrier will help shield the inside habitat from small asteroid impacts. AND keep the sun-facing surface cool!
You can then let the coin face the sun if you like.

Alternatively, what if you set your coin so that it is not quite edge-on to the sun? Align it so the shadow of the sun-ward dirt bottom does not fall on the far edge of the coin.

At "noon" you'd see the sun just to the left of the skyring.
At midnight, you'd get a few rays glancing up from below only if you are on the far right side of the ring.