Stef said sharply. ‘You know, ColU, you should have warned us about all this.’

‘But I was never sure. I can never lead; I can only advise.’

‘It’s a galaxy,’ Beth said, a little wildly. ‘Even I know that much. Like our galaxy, the Milky Way … But what the hell’s it doing up there? Is it our galaxy?’ She shook her head. ‘I grew up on Per Ardua, remember, on the day side. I never even saw the stars until I got to Mercury. Has Proxima been – I don’t know – flung out of the galaxy somehow, so we see it from the outside?’

‘Nothing like that,’ the ColU said gently.

‘That’s not our galaxy at all,’ Stef snapped. ‘That’s Andromeda, isn’t it? Bigger than ours, I think. The two galaxies were the biggest of the local group. Now, when I was a kid playing at astronomy with my father, on the rare nights we had clear skies in Seattle’ – and, in some realities, with her impossible sister Penny by her side – ‘we used to look for Andromeda. Fabulous in a telescope, but you could just see it even with the naked eye. A smudge of light. Now that, I would say—’ and she started taking rough sightings of the width of the object with her thumb ‘—is, what, thirty times the apparent diameter of Earth’s sun?’

‘More like forty,’ the ColU said.

Mardina was staring at her. ‘So how did that thing get so big?’

‘It didn’t. It got closer.’ Stef closed her eyes, remembering her own basic astronomy classes from long ago. ‘In my time Andromeda was two and a half-million light years away. Right, ColU? But even then we could see it was approaching our galaxy. The two star systems were heading for a collision, which – well, which would be spectacular. Now, as I recall the best predictions for the timing of that collision were way off in the future. Four billion years or more?’

‘More like four and a half,’ the ColU said.

Stef squinted. ‘So if that beast, which is around two hundred thousand light years across, is that apparent size in the sky, I could estimate its current distance—’

‘Done,’ the ColU said. ‘Colonel Kalinski, I now know we have travelled – or rather the Hatches have taken us – some three and a half billion years into the future. That is, after the epoch from which we set out.’

Beth, Mardina, Chu just stared at each other, and then into the slate hanging from Chu’s neck, as if the ColU’s mind resided there, as if behind a human eye.

But Stef understood immediately. ‘Yes, yes. So the collision is still a billion years away—’

‘If it were to happen at all,’ the ColU said enigmatically.

‘I wonder what it must have done to cultures who emerged after our own, to have that hanging in the sky. Growing larger century by century. How many religions rose and fell in its light, awed and terrified?’

‘We’ll never know, Stef Kalinski,’ the ColU murmured.

‘And, over three billion years – that’s presumably more than enough time for all the processes we’ve seen here on Per Ardua to have come about. For almost every trace of humanity to have eroded away. Even for species from two different star systems to find a way to evolve into one ecology.’

Mardina looked around the strange sky. ‘I don’t understand. Three and a half billion years … It’s meaningless. Where is Terra? Where’s the sun?’

‘I’m afraid I’m not sure,’ the ColU said. ‘The sun and the Alpha Centauri system, the Centaur’s Hoof, were once near neighbours. But by now they will have wandered far from each other, as the galaxy has turned on its axis. Earth, Terra, and the other planets will still orbit the sun. But Earth is probably lifeless; the sun, slowly heating, will have sterilised the inner planets – oh, as much as two or three billion years ago. But the ageing sun has not yet entered its terminal cycle, the red giant phase when the sun will swell and swallow the inner worlds.’

Earth lifeless. Suddenly Stef shivered, despite the comparative warmth of her clothing. To be alone on this world was one thing. To be taken out of one reality stream and dumped in another was extraordinary. But to be stranded in a future so remote that Earth was dead, that presumably nothing like the humanity she had known could still survive …

‘This is terrifying,’ she murmured.

‘Indeed, Colonel Kalinski,’ the ColU said.

Chu was looking around the sky. ‘I rode on starships,’ he said slowly. ‘I was held in slave pens. But when I passed windows, I glimpsed the skies of many worlds. And this is quite different. I mean, even aside from the approaching star storm, Andromeda. The stars seem more dim, more sparse.’

‘That’s a good observation,’ the ColU said. ‘Even in our time the great ages of star making were ending. Now there are fewer young stars, more ageing ones.’

Chu asked, ‘And where are the other stars of the Centaur’s Hoof? They should be two brilliant lanterns in the sky.’

‘Even Alpha Centauri has evolved with time,’ the ColU said sadly. ‘Its stars were older than the sun. The brightest of the main pair will have lapsed into its red giant stage perhaps half a billion years ago, sterilising any worlds in its own system, and its partner’s, before collapsing to a white dwarf – and Proxima will have become decoupled from its weakening gravity field. The lesser of the main pair would have had many billions of years left before it, too, entered its terminal phase. Smaller stars last longer. Proxima, the runt of the litter, would likely have lasted for six trillion years before running out of its carefully processed hydrogen fuel. But Proxima, now, is alone.’

‘You say would,’ Stef said. ‘Would have lasted trillions of years. And you seemed remarkably precise in your estimate of the date, given only a cursory look at this sky above us—’

‘As I told you, I do have more information,’ the ColU said. ‘About the future of the universe, gathered during the long years of my journey home to Earth in the Malleus Jesu. Subtle signs of times to come: evidence of titanic future events, smeared across the sky of the present. Events whose date I was able to estimate. Once I saw that Andromeda was so close, once I realised roughly what epoch this is, it was easy to deduce that they would have brought us, not to some arbitrary earlier point, but to this point in time. This most special time of all. With more observation, especially of the cosmic background radiation, I will be able to be more precise still—’

‘They,’ Stef snapped. ‘They brought us here. You mean the Hatch builders. Who Earthshine called the Dreamers.’

‘The Dreamers – yes.’

Chu asked now, ‘And what is so special about this time, this future, this age?’

‘Nothing.’ The ColU sighed. ‘Nothing, save that it is the last age of all.’

‘The End Time,’ Stef said.

She saw Mardina place her hand on her belly, over her unborn child.

That was when Titus and Clodia came clambering up the slope. ‘Here you are. Camp discipline: leave a note before you all clear off next time.’

Beth said, ‘We’re stargazing. Looking at that.’ She pointed up at Andromeda.

Titus snorted. ‘Who cares about lights in the sky? I’ve got something much more important to show you. Come and see what we found!’

CHAPTER 66

It was a walk of around three kilometres – two of Titus’s Roman miles.

They came down off the flank of the mountain and made their way along a dry, shadowed valley. The going was easy, even for Stef, who had walked little save around one campsite after another since the expedition set off. Titus and Clodia both carried torches, of dry stems bundled up and dipped in pots of marrow; they burned, if fitfully. But the glow from Andromeda was surprisingly bright, especially from that brilliant central core. Billions of suns in lieu of moonlight, Stef thought idly.

And, as Titus had predicted, when she came to the structure Titus and Clodia had found, Stef too forgot the wonders of the sky. She even forgot, for a while, the ColU’s dark and still obscure mutterings about the End Time.