The most important of these were Umbriel and Titania, two moons about a quarter million and two-fifths of a million kilometers out from the residential band of the planet, respectively, and just below and just above a thousand kilometers in diameter. These were tiny, on the scale of the satellites of Jupiter, but physical size was no necessary indication of importance. The fact is, there is a lot of area available on a solid moon. We become accustomed to the limitations of the city-bubbles in the atmospheres of the major planets, where space is always at a premium though distances between cities are vast. On an airless moon like Titania the cities still need to be enclosed by domes, but many, many domes can be set up in limited territory. They won't collide; the common anchorage makes it feasible. So an entire nation of several tens of millions of human beings resides on a moon that would fit inside the merest whorl in a major planet's atmosphere. Titania, small as it seemed in space, had inherited the British Empire tradition.
