The story of how I came to be on Earth, alone, freezing half to death in your extraordinary ‘snow’, began four years ago, when I was nearly eight. As I have explained, I was already nearing the end of my period of formal education. ‘School’, you would call it.

There were maybe twenty of us visiting the Earth Zone, led by our ‘teacher’, Mr Park, who, at thirty, was one of the oldest people I knew. Of course, I had no idea then that I would be back in Earth Zone a few years later, not as a visitor but as a liberator, freeing an exhibit from this prison.

We walked in silence on the enclosed walkway several metres above the ground, viewing with astonishment the landscape below us. The grass and bushes were untamed and shaggy; pale, fluffy animals with four legs and dark faces ate the grass! That was most interesting.

There were no real birds. The Earth Zone is entirely enclosed by an unseen quantoplasmic force field: real birds would simply fly into the force field and be killed. Instead mechanical birds flitted here and there, and even made high-pitched noises just like, it is said, their counterparts on the real Earth.

My companion Av nudged me and pointed to another, smaller animal that was coming towards us beneath the walkway, waving its tail. ‘Dog,’ she said, trying her hardest to speak English, the most popular language on Earth.

I was transfixed as it got nearer. Some of my classmates shrank away even though we were well shielded from it by the height of the walkway.

‘Dangerous creatures … the same as wolves … they do not clear up their own bodily waste … they are kept in human homes …’ said Mr Park, and everybody around me tutted and shook their heads at the strange and filthy habits that the Earth people had.

‘In homes!’ muttered Av disapprovingly.

Perhaps it was just me? It seemed like it might be rather nice to share your home with one of these friendly-looking creatures with the waving tails. But I said nothing, of course.

‘This is the Northern Zone,’ said Mr Park. ‘It is a recreation of parts of Earth common north of their equator, especially the landmasses they call Europe and North America …’

As Mr Park droned on, we carried on walking and the dog followed below us. Av and I were at the back of our line and nobody else was looking.

‘See, Hellyann, it likes you,’ said Av quietly so that Mr Park would not hear. The dog came closer. Its tail was much hairier and longer than mine, and it waved from side to side quickly.

The line of students stopped while Mr Park pointed to some clumps of twigs in the trees that the robotic birds had put there to ‘sleep’ in and lay eggs – fake, naturally.

‘We shall now proceed through to the Human Being Area, where right now it is winter. You may experience sensations of considerable cold. Do not be alarmed – it is not dangerous. Can anybody tell me what happens in winter?’

Av put her hand up. ‘Water freezes, sir?’

‘Very good. Anything else? What falls from the sky?’

‘Birds, sir?’

‘No, Av, not birds, but frozen …?’ He left the question hanging. ‘Hellyann?’

‘Water, sir? Snow, sir!’

‘Indeed. Snow. Not seen naturally on our planet since the last Frozen Period. Here, it is recreated artificially. Stay in your pairs. We will be encountering human beings. They are quite safe. Do not approach them, however, and in the unlikely event that they approach you, simply walk away. Is that understood?’

We all murmured, ‘Yes, sir’, and followed Mr Park to the edge of the Northern Zone and through the tunnel to the Human Being Area.

This is where I had an encounter that – four years later – led to me being on Earth.