‘Earth has grown old,’ he said.

Luru was watching him, apparently interested in his reaction. ‘Old like its children.’

‘It is well guarded,’ Mela murmured.

‘There is nothing more precious,’ Luru said.

On its final approach to the planet the flitter cautiously descended through shells of automated sentinels, and artificial suns that swooped on low orbits, casting splashes of yellow light. Luru said that not all those satellites carried weapons. Earth’s magnetic field had failed. The sun was far away now, but the electromagnetic environment around a gas giant was ferociously energetic. Where nature failed, humans had to step in; and so devices orbited the Earth to protect it with new shields of magnetism.

The flitter ducked deep into the air, and the sky turned a muddy red-brown. Everybody stayed silent as the ground of Earth fled under the ship’s prow.

The cities were sparsely scattered, and Symat could see no logic to their positioning. Perhaps they had been placed along the banks of long-dried rivers, or at the shores of vanished oceans; the cities endured where geography had eroded away. Many of the buildings were airy confections of glass and light that wouldn’t have looked out of place on Mars. But these modern cities were fragile flowers that grew out of mighty ruins, covered by drifts of red dust.

Mela picked out patterns. ‘Look. Lots of those old ruins have got circles in them. See, Symat?’

She was right. Sometimes the circles were obvious, rings of foundations or low walls that could be kilometres across. In other places you could only spot the circles by the way other ruins fitted around them, filling up their interior spaces or crowding around their circumferences.

Luru’s eyes, black as night, gleamed bright as she peered out at this ancient architecture. Perhaps in these traces she saw some trace of her own long life, Symat mused.

In every city they passed over Symat spotted transfer booths. Even Earth, which Luru and her Ascendents had laboured so long to save, was draining of its people.

Wild things lived on the lands between the last cities. The flitter passed over what looked like plains of grass, even forests of stunted trees, and occasionally its passage scattered herds of animals. But there were swathes of vegetation that wasn’t even green.

The flitter at last swept over a southern continent that seemed even more worn-down than the rest, and came to rest at the outskirts of yet another city.

Symat deliberately jumped down from the hatch, falling a half-metre or so to the dusty ground. He fell slowly, though once his feet were planted in the dirt of Earth, invisible inertial systems ensured his weight felt normal to him. Gravity was indeed low here, he thought, somehow lower than Mars’s. But Earth, the mother world, had always defined the standard of gravity: how, then, could its gravity be reduced?