Days on Mars were longer than days on Earth by almost exactly one hour. But rather than giving Mars a twenty-five-hour day, the Thunderhead decided to change the nature of time itself. “The measurement of time is a human construct,” it had reasoned, “which means it can be reformed for planetary convenience.” And so the seconds on Mars became just a tiny bit longer, as did the minutes, as did the hours. A day still measured twenty-four, but each of those hours was nearly two and a half Earth-minutes longer. Which gave birth to expressions like “a Martian minute.”
