Some of the worlds have small seas, and people sail on them, I know. But it’s not the same as solar sailing. A boat can sail into the wind, but we can’t—there’s no other medium for us to push against, the way a boat’s keel works against the water. So we can’t tack, in the nautical sense. But we can use orbital mechanics to our advantage. We’re in a gravity well, you see, and that means we have angular momentum to play with. The sails can add or subtract from our motion around the Old Sun, if we tilt them
