A World of Two Halves

Life on Earth

Life on Earth during synchronous rotation? This edition published by Sphere Books 1969.

No-one can be in any doubt as to how critical our Sun is for the survival of humanity. Without the continuous flow of sunlight, there would be little future for our race, or indeed any life anywhere in the Solar System, at least until some form of space-faring society develops in the longer-term future.

In a previous Odyssey post, When Your Sun Behaves Badly, I talked about the very disturbing possibility that the Sun might one day fail to provide its life-giving energy, and the dire consequences for the human race in such an event. But the opposite – destruction by increased solar radiation impacting on the Earth’s surface – could be even more immediately devastating for life, and has been a regular feature of science fiction over the years.

The 1961 film The Day the Earth Caught Fire depicted our planet’s orbit being moved closer to the Sun due to huge simultaneous nuclear bomb tests by the Americans and the Soviets – very much an apocalypse of its time.  The level of heat rises inexorably and the human race appears to be doomed. In the more recent 2018 television series Hard Sun, we seem to be facing an extinction event in five years’ time. However, in what might be considered a clear sign of our times, the government’s prime concern on this occasion seems to be to prevent the public knowing anything about it, or at least to encourage them to disbelieve the rumours of what might really be happening.

The 2011 TV movie Earth’s Final Hours is based on the proposition that a mass of extremely dense matter blasts through the Earth, stopping its rotation and causing its magnetic field to break down, resulting in a vast increase in solar radiation on the surface.  However unlikely such an outcome from an event of that kind might be in reality, a government cover-up has little chance of success when the Sun is standing still in the sky. On the other hand, though, a future where half the planet remains in permanent daylight, and the other half in perpetual darkness, means that whoever gets to live in the limited “green zone” along the terminator might survive. No-one else stands a chance and, needless to say, in this movie a powerful elite begins fighting to ensure a safe future for itself.

Tidal locking of a planet can indeed result in synchronous rotation – one side constantly faces its sun, much as the Moon is tidally locked with the Earth, in which case it is feasible that one-half burns while the other half freezes.  Until radar observations in 1965 proved otherwise, it was thought that this applied to the planet Mercury, which is the way the planet was portrayed when Dan Dare visited it in the Marooned on Mercury comic strip story in The Eagle from 1952.  If such a process should happen to the Earth in some far distant future, the prospects for humanity would be grim indeed.

This is the premise of Brian Aldiss’ classic 1962 novel Hothouse.  Plant and animal life has evolved to cope with endless daylight in the tropical forest which covers the side of the Earth that always faces an enlarged Sun.  Ferocious vegetation is in a constant battle for survival against other plant life and the limited number of animal species which still exist, including the remnants of the human race who are close to extinction.  Admittedly, the laws of physics would not permit a planetary orbit such as that described in the story, where a tidally locked Earth is linked to the Moon by giant webs, but the imagery is powerful and the plight of the sorry remains of humanity stays in the mind.

What is also significant is that there are other, non-human, intelligent species in the story who recognise that the Earth’s doom, as the Sun continues to expand, cannot be avoided.  It may not affect the current generations, but their descendants have little hope.  How any thinking being can come to terms with the forthcoming extinction of its race is a key feature in all such stories, and a worrying thought in the absence of any realistic means of leaving the home planet for good.


Richard Hayes, Assistant Editor (Odyssey)

With a lifetime’s interest in science, history and human behaviour, Richard Hayes focuses his writing on how the imagination has created the world in which we live, and where it may lead us in the future.  Odyssey, the e-magazine of the British Interplanetary Society, draws on the rich treasury of science fiction to explore many fields of speculation, enabling us to glimpse what might yet be, both here on Earth and out amongst the stars.

For related Odyssey posts, please click here: Colliding Worlds | Life on the Brink

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