- There is a solid surface.
- Somewhere on the surface, the temperature exceeds 2,230 C, such that pure silica vaporizes.
- Elsewhere on the surface, the temperature is at most 25 C, such that humans can be comfortable.
- In the human-comfortable temperature region, the surface gravity does not exceed 2g.
- The surface atmospheric pressure is at least 0.25 bar.
Life does not need to have arisen naturally.
I think I have figured out a way to achieve this, but some peer review would be appreciated! What I have in mind is a sort of hot mini-Mesklin--a super-Earth that rotates extremely quickly, such that it has extreme obliquity, and is also sufficiently close to a hot star. (This may need to be a close system of multiple stars for the planet to get enough light while also being far enough away to not end up tidally braked, and keep its high rotation.)
With little or no axial tilt, such a planet would present a small region near the equator straight-on to its sun, receiving the maximum concentration of light. Over the majority of the surface, the ground would be at a very low angle to the sun, thus being heated considerably less. Extremely fast rotation would also produce a large number of atmospheric circulation cells, impeding the transfer of heat from the equator towards to poles. Thus, with just the right parameters, we should be able to get a planet on which silicate rocks vaporize on the equator, then condense and rain out as glass in the low latitudes where the surface begins to curve away from the sun, and temperatures drop to survivable levels near the poles.
So, what have I got wrong? Am I overly optimistic? If this can't be made to work, is there any alternative approach that can get me glass rain on a planet that humans could land on?