I have always been fascinated with the arbitrary nature of the world we live in. Why are there still seven days in a week, or 52 weeks in a year? Our modern world is built at least in part on ancient ones: those calendars date back to ancient Mesopotamia, where they were of religious import. Time is fascinating: a day so short, a life so long. And our little tinpot year, composed of a mere 365 days – the period our planet takes to orbit the sun. Supposing we lived on a planet whose orbit round its sun took 5,000 years. What then?

This planet of mine was imaginary, with strips of science and history in its palisades as mortar. Little did I know or care that there was a real counterpart, awaiting discovery in the future. And now revealed to us by Nasa's Kepler space telescope.

There is a saying that curiosity killed the cat, but it's curiosity that keeps many of us alive. Some time ago I started to do some research for a new book. Immediately I had a name for the planet that was to be involved: Helliconia. I drew a plan. I made lists of figures and their relationships. The figures became more real when they gave way to words, to names. Freyr was the name of the sun.

It was a modest sun, much like our own. But that planet, Helliconia, with its seasons, orbiting Freyr, was insufficient for belief. So it was that planet and sun were drawn into the orbit of a much larger sun, passing a few light years away, becoming known to the Helliconian humans as Batalix. And the smaller bodies took 5,000 years to achieve their Batalix-ruled orbit.

For a while I was stumped about the local vegetation. On a train one evening, I looked out to see Didcot power station in the waning light. Steam poured forth and, by a curious effect of shadow, the clouds were turned black with shadow. I had it! This was a Helliconian tree in the long summer, with its foliage on display; come winter, the leaves and branches would sink back into the hollow trunks. They would melt into a kind of tallow, sealing themselves off from the long winter. From this astonishing vision, all alien vegetation was born.

My planet possesses three large continents, the central and most hospitable being Campanlatt (although to the east, there is mountainous country, where several peaks rise into the lower stratosphere). We learn of life on this planet because Earth has established an observation post in Campanlatt. The observers living there cannot visit the world below; that would mean death (I required an unfilterable virus to fill the air). Helliconia Spring, the first novel in the trilogy, appeared in 1982, dedicated to my elder son.

The amazing thing is that Helliconia has now turned up in what we call "reality", just a few light years away. "Kepler 22-b", as the spoilsports call it, was first located by Nasa's telescopes in 2009, but the discovery of this "new Earth" was feted by the press this week. This real Helliconia, Nasa reveals, is situated 600 light years away, its surface temperature reported as 72F. So there is little chance that we can visit it to discover whether my two opposed races – the humans dominant in summer, the phagors dominant in the long winter – also exist in reality. Fans from all over the world have written to me to congratulate me on my prescience. No word from those who once jeered at the unlikelihood of my saga.

Science always has something new for us in store. Cern's scientists – underground in Switzerland, secluded from the problems of the EU, working at the Large Hadron Collider – are hoping to discover how our universe came to be as it now is. I wait with curiosity; no guesses right or wrong, this time. But one can only wonder if the entire caboodle of our universe is not the outburst of some gigantic extra-cosmos writerly imagination.