Maybe fifty yards from the Shoemaker, she turned to face the sun. The light glared through her gold-tinted faceplate. There stood the Shoemaker, Henry on it watching her, a little gold-coloured platform with a white snowman perched on the top. The lander looked strangely light, as if it might blow away. Its gaudy gold and black and silver looked ludicrous: overdesigned, for this gentle, subtle landscape.

Behind the Shoemaker she looked across the width of a big crater, a bowl bigger than a football stadium, shadows stretching across the ground towards her from rocks and craters. She could see the old Apollo lander, nestled close to the crater’s shadowed far wall, a squat, boxy structure, unmistakeable.

And there, only a hundred yards from the Apollo, stood the second Shoemaker, laden with the supplies that would keep them alive.

“How about that,” she said. “Can’t be more than six hundred feet away.” She felt elated — the first lunar landing for more than thirty years, and it was pinpoint accurate. “Outstanding.”

“You got the job,” Henry said drily. “Now, will you help me down from here?”

So here was Henry, unbelievably, standing on the Moon, a geologist on the ultimate field trip. He turned, slowly, trying to understand where he was. The sun dominated seeing on the Moon, he realized immediately.

The sun was like a giant, intensely bright searchlight, pure white, overwhelming everything, and the mental picture he built up of the landscape here depended completely on the angle to the sun.

At zero phase angle — if he looked down-sun, with his own shadow stretching across the untrodden surface — it was difficult for him to make out shadows. Most objects were visible, but the contrasts were washed out. But he could see shadows if he looked cross-sun, so the trick was to look from left to right, to pick up the shadows, and shapes and sizes and glints, and he could orient himself that way. And if he walked up-sun, with the shadows stretching towards him, the sun was very bright, glaring in his visor.

When he looked at his own shadow the sunlight around it came bouncing straight back at him. The shadow of his body was surrounded by a glow, a halo around his helmet.

He inspected the mineral ground. Cinereous, he thought. The colour of ash…

But there were colours here, he realized suddenly.

He stopped and looked around more carefully.

If he looked in the direction of the sun, the ground looked a pale, golden brown. It was the same if he looked away from the sun, beyond his own long shadow. But to left or right the colours got darker, to a richer deep brown. If he looked under his feet, or at a handful of soil in his hand, the colour was a deep charcoal grey, sometimes even a black.

But anyhow the Moon colours looked pale and lifeless when he looked at the blue armbands on his suit, his blue lunar overshoes, the brilliant black and gold and silver of the Shoemaker, and especially the ice-blue of the Earth, when he looked up.

He knew he would have to learn to take account of all this, learn to read the landscape on its own terms, in its own conditions of light and shadow.

He did a little geologizing.

He was standing on a dark plain, its surface evidently sculpted by craters, of all dimensions, craters on craters. There were rolling hills, almost like dunes, their form softened and fluid, their flanks littered with boulders thrown out of the larger craters. And close by he could make out smaller craters, almost rimless pits in the soil, and the centre of each one was marked by a spot of fused glass, a remnant of the punch which had dug out that particular pit.

It was a landscape unlike any he had seen on Earth.

The mountains — foothills of the Aristarchus crater rim walls — rose up like topped-off pyramids into the black sky, their sides dauntingly steep. There was no easy comparison with terrestrial features; the hills were neither as crag sharp as the granite of the Rockies, nor as smoothly rounded as the ice rivers of Norway.

And besides, almost all of Earth’s features — certainly all of the mountains — were young, at any rate by comparison with what he would find on the Moon. Some of the mountains of the Moon were almost as old as the Solar System itself.

But the shadows of the mountains were not the wells of darkness he had expected, for light, reflected from nearby slopes and plains, softened the shadows. The light, reflected from the rocky ground, was, of course, Moonlight: precisely that, the very light which illuminated Earth’s night sky.

He’d ridden through Moonlight across a quarter of a million miles. And now, standing here, he and Geena were bathed in it.

He shivered.

He took a step forward, over dust and broken rock. The Moon gave him a firm footing, beneath a layer of looser dust that compressed like unpacked snow.

The loose stuff varied from place to place, from maybe a few inches thick to perhaps a foot. He knew the reason for that: the regolith was created by a hail of micrometeorite bombardment, and it deepened and matured with time.

So when he walked into a patch of softer dust, he was walking somewhere older.

Anyhow, nowhere did it cause him a problem; the Moon, as a geological field site, would, it seemed, be an accommodating place to work.

In fact, he felt an odd ache as he looked down at the dust billowing around his feet. He wanted to take off his gloves and run his bare fingers through the soil, connecting with the Moon. But that was, of course, impossible; he was the alien here, encased in his bubble of Earth murk, and he must stay that way.

He walked further.

He bent and, with both hands, pulled a big rock out of the ground. He had to push his fingers into the crackling surface, smashing up agglutinates, rock fragments glued together by solar wind particles, to get his hands around the rock.

From above the rock looked smooth, almost flat against the ground, like a glacier deposit. But when he dug it out he found its underside, buried in the regolith, was sharp and angular, and maybe ten times as bulky as the portion that had shown above ground, like an iceberg. And the buried surfaces were sheer, lacking the sheen of zap pits and impact glass of the exposed section.

This rock, casually dropped here after some ancient impact, had been eroded flat by an aeon of micrometeorite rain.

He brushed off the dust and held the rock up to his faceplate.

This was a breccia, a compound lump of rock whose fragments had been crushed, ground, melted, mixed and then bound together in a shock melt. When he turned it in the flat sunlight he could see the sparkle of glass, the recrystallized minerals that were holding this lump together.

This rock, in fact, almost looked like a vesicular basalt — a pumice, riddled with bubbles left by gas. But the heat that formed it came not from volcanism but from the energy of the catastrophic fall of a giant impactor. And he thought he could see that this breccia was in fact itself made up of earlier breccias, breccias nested in breccias like biblical generations, remnants of still earlier impacts. In this one chunk there might be pieces of ancient anorthosite crust, mare lavas, even solidified dregs of the original magma ocean.

He weighed the lump of breccia in his gloved hand. Its weight was barely discernible in the feeble gravity. And yet, just looking at it, he felt echoes of the almost inconceivable violence which had shaped the Moon’s early history, sensed the processes which had formed this rock since, processes unlike any on Earth.

And now Geena was calling him, telling him to come with her to the Apollo site.

He put the rock back where he had found it, back where it had lain for a billion years, and loped away through the morning sunlight.