“What, to Saturn?”
“To Jupiter, actually.”
“I don’t want to do that. My life is here, my work. I traveled the system enough when I was young.”
He nodded unhappily. “And… you are quite certain Alex didn’t leave anything for you? Something to give to me, in case something happened to her?”
“Yes, I’m sure! There’s nothing! She didn’t do things like that.”
He shook his head. They sat in silence as the tram slid over the dark face of Mercury. To the north some hilltops were just sparking white with the rising sunlight. Then the top of Terminator’s dome appeared over the horizon, like the shell of a transparent egg. As it cleared the horizon, the city looked like a snow globe, or a ship in a bottle-an ocean liner on a black sea, caught in a bubble of green light. “Tintoretto would have liked your city,” Wahram said. “It looks like a kind of Venice.”
“No it doesn’t,” Swan said crossly, thinking hard.
TERMINATOR
Terminator rolls around Mercury just like its sunwalkers, moving at the speed of the planet’s rotation, gliding over twenty gigantic elevated tracks, which together hold aloft and push west a town quite a bit bigger than Venice. The twenty tracks run around Mercury like a narrow wedding band, keeping near the forty-fifth latitude south, but with wide detours to south and north to avoid the worst of the planet’s long escarpments. The city moves at an average of five kilometers an hour. The sleeves on the underside of the city are fitted over the track at a tolerance so fine that the thermal expansion of the tracks’ austenite stainless steel is always pushing the city west, onto the narrower tracks still in the shade. A little bit of resistance to this movement creates a great deal of the city’s electricity.
From the top of the Dawn Wall, which is a silvery cliff forming the eastern edge of the city, one can see the whole town stretching out to the west, green under its clear dome.