The second silicate asteroid, called Solettaville, had been pushed near this Lagrange point. There the solar sailmakers spun the mirror sheets out into a complex web of slatted rings, all connected and set at angles, so that they looked like a lens made of circular venetian blinds, spinning around a hub that was a silver cone, with the cone’s open end facing Mars. This huge delicate object, ten thousand kilometers in diameter, bright and stately as it wheeled along between Mars and the sun, was called the soletta.

Sunlight striking the soletta directly bounced through its blinds, hitting the sun side of one, then the Mars side of the next one out, and onward to Mars. Sunlight striking the annular ring in its polar orbit was reflected back and in to the inner cone of the soletta, and then was reflected again, also on to Mars. Thus light struck both sides of the soletta, and these countervailing pressures kept it moving in its position, about a hundred thousand kilometers out from Mars— closer at perihelion, farther away at aphelion. The angles of the slats were constantly adjusted by the soletta’s AI, to keep its orbit and its focus.

Through the decade when these two great pinwheels were being constructed out of their asteroids, like silicate webs out of rock spiders, observers on Mars saw almost nothing of them. Occasionally someone would see an arcing white line in the sky, or random glints by day or by night, as if the brilliance of a much vaster universe were shining through loose seams in the fabric of our sphere.

Then, when the two mirrors were completed, the annular mirror’s reflected light was aimed at the cone of the soletta. The soletta’s circular slats were adjusted, and it moved into a slightly different orbit.

And one day people living on the Tharsis side of Mars looked up, for the sky had darkened. They looked up, and saw an eclipse of the sun such as Mars had never seen: the sun bit into, as if there were some Luna-sized moon up there to block its rays. The eclipse then proceeded as they do on Earth, the crescent of darkness biting deeper into the round blaze as the soletta floated into its position between Mars and sun, with its mirrors not yet positioned to pass the light through: the sky going a dark violet, the darkness taking over the majority of the disk, leaving only a crescent of blaze until that too disappeared, and the sun was a dark circle in the sky, edged by the whisper of a corona— then entirely gone. Total eclipse of the sun. . . .

A very faint moiré pattern of light appeared in the dark disk, unlike anything ever seen in any natural eclipse. Everyone on the daylight side of Mars gasped, squinted as they looked up. And then, as when one tugs open venetian blinds, the sun came back all at once.

Blinding light!