A Song of Three Seasons: The SF Game of Thrones

It is a world where the seasons last for years, where summers can span decades and devastating winters can threaten to destroy civilisation altogether. In the warmth of summer, princes and kings do battle and play their games of thrones. But in the depths of the coldest winters, the humans seek shelter behind the walls of their castles and cities. Strange creatures appear our of the uttermost north and move south in great migrations which threaten humanity with extinction. This all unfolds on a world called...Helliconia?

Maps and charts of Helliconia, created by Brian W. Aldiss whilst writing his trilogy.

In 1982 Brian W. Aldiss published the novel Helliconia Spring. One of the grandmasters of science fiction, renowned for books like Hothouse, Non-Stop and Report on Probability A, as well as works of mainstream fiction and poetry, Aldiss had made the surprising decision to return to SF on a grand scale. For this trilogy he tapped a wellspring of local talent and expertise. Living in Oxford, with the university and its plethora of experts in every field of science imaginable at hand, Aldiss set out to create the single most detailed, expanse planet ever described in science fiction. And he succeeded. Helliconia remains the most remarkable feat of worldbuilding in SF history, outstripping even Frank Herbert's Arrakis (famously detailed in his Dune novels) for the vigour of its scientific plausibility.

At the heart of Aldiss's trilogy is an idea that modern fans of fantasy may find familiar: a world where the seasons last not just three months, but years and even centuries. But unlike George R.R. Martin's A Song of Ice and Fire, the seasons of Helliconia are rooted in real scientific principles.

Helliconia is an Earth-like planet approximately 28% larger than Earth but with a more pronounced axial tilt of 35 degrees. This results in the planet having enormous icecaps which are larger than Earth's, but the planet nevertheless retains as much surface area as Earth, extending over three continents: the northern polar continent of Sibornal, the southern polar continent of Hespagorat and the equatorial continent of Campannlat, which is linked to Sibornal by a land bridge.

More important is the make-up of Helliconia's star system. Helliconia orbits at G4 star Batalix (an orange dwarf, somewhat smaller and less bright than our sun) at a distance of somewhat less than 1 AU (so Helliconia receives slightly less solar output than Earth). Batalix, in turn, orbits the A-class blue supergiant star Frey in a highly elliptical orbit. At apastron, the moment of greatest separation, Batalix is 710 AU from Freyr (for comparison, Pluto at its most distant from the Sun is still only 49 AU away); at periastron, the moment of minimal separation, Batalix is 236 AU from Freyr.

The orbits of Helliconia and Batalix around the star Freyr (not to scale).

The result of this orbital dance is that Helliconia enjoys a "small year" of roughly 480 days, the time it takes to orbit Batalix once, and a Great Year of 1,825 small years (2,592 Earth years). During a Great Winter, when Freyr is so distant it becomes merely the brightest star in the sky, the great ice completely buries Sibornal and extends deep into Campannlat, forcing humans to live in a narrow habitable strip across the equator. During a Great Summer, where Freyr dominates the sky and the ice has withdrawn far to the north and south, there are great exoduses from the equatorial belt (where great fires consume the forests) in favour of the coasts and the arctic continents.

It is revealed later in the novels that this arrangement is, relatively speaking, new: Batalix was captured by Freyr's gravity during a chance encounter eight million years ago. Prior to that time Helliconia was permanently a much colder world, and it was the capture that allowed humanity to evolve from an earlier primate species.

This push and pull of civilisation across millennia is echoed by a more personal threat: Helliconia is also home to a second sentient species. The phagors or ancipitals are a race of fur-covered creatures similar to mythical minotaurs. The phagors are optimised for life in the cold and are stronger and more formidable than humans in personal combat; however, they are (arguably) less intelligent and have never developed technology beyond that of the hunter-gather stage. During the Great Winters the phagors are the dominant species on Helliconia, whilst humans gain the upper hand during the Great Summers and force the phagors back to the polar continents.

Aldiss uses this ebb and flow of the seasons and species to drive his story. In each of the three novels in The Helliconia Trilogy (Helliconia Spring, Helliconia Summer, Helliconia Winter) Aldiss uses the change of seasons to chronicle the rise and fall of kingdoms, civilisation but, more important, individuals, who change, grow and learn from the ever-changing world around them.

A Song of Ice and Fire can clearly be seen as the fantasy equivalent of Helliconia. Scientifically and astronomically-minded fans have spent large amounts of time coming up with maps and charts of how the seasons might work in such a star system, sometimes drawing on dark matter or invisible neutron stars to explain the required orbital eccentricities. They are sadly doomed in such attempts, for there is no such scientific explanation: George R.R. Martin has been constant in his promise that the reasons for the long seasons of Westeros and Essos are magical, not scientific.

Still, they might take comfort that, fourteen years before Martin published A Game of Thrones, another author took on the same concept with a scientific viewpoint and delivered one of the greatest works of science fiction ever published. The influence of Helliconia on A Song of Ice and Fire is speculative - Martin has almost certainly read the series given its prominence but has never mentioned it to my knowledge - but certainly the parallels between the two series are fascinating.