 What is the twilight zone?
Across to the right was a group that Baron knew vaguely—Andean climbers, or at least two of them were. After that, I followed Sanderson’s work in the Twilight Lab up there and began to get Brightside into my blood, sure as death. I first met him on Venus; we spent five years together up there doing some of the nastiest exploring since the Matto Grasso. “I want to make a Crossing at perihelion and I want to cross on the surface.
 The place between Brightside and Darkside.
 The place at the end of the Brightside Crossing.  A lab where they study the Sun.  The place between Brightside and Darkside.  A lab where they study Mercury.