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114 - Petunias

El Cid

on Sept. 29, 2016

So maybe they're not such an odd couple after all?




In the foreword to the collected Volume One of his excellent science fiction series LOW, Rick Remender relates his sense of overwhelming dread when he first learned that some day the sun is going to heat up, enlarge, and devour the Earth. It was something more profound than confronting his own individual mortality; this meant that everything humanity has created will eventually be erased forever. “I was 7 or 8 years old,” he writes, “when I got my first true taste of nihilism.”

But it doesn't need to be so. The Earth's still got at least 500 million years before the sun starts to cook the oceans away, and 5 billion years before it goes red giant. That's a lot of time to work with, and humans are crafty little creatures.



There are lots of ideas that have been proposed, most of them pure science fiction – such as building a solar sail 20 times the size of the Earth to tow us out to a safe distance. But one of the more elegant ideas is one which is not too far from our current capabilities. Astrophysicist Don Korycansky believes that if we can divert a large enough asteroid into an orbit that grazes the Earth – at a distance of about 10,000 km every 6,000 years – then the periodic gravitational tugs should be enough to gradually stretch out the Earth's orbit at a rate that keeps pace with the sun's increasing temperature. It would take millions of years for the Earth to reach a safe enough distance that it wouldn't be consumed by the sun when it enters its red giant phase, but that's more than fast enough to beat the Earth's ticking doomsday clock.

If it works, we'll buy the Earth another 6 billion years of habitability. But if it doesn't work – if we screw up our calculations even a little bit – then we'll end up impacting the Earth with an asteroid large enough to sterilize the entire surface of the planet. No pressure!

So what happens after 6 billion years? The sun becomes a white dwarf, and the solar system – the Earth included – gets very, very cold. But that's not necessarily the end either. Though the oceans would freeze on the surface, they'd still be liquid at the bottom. Organisms living around hot vents on the ocean floor would keep on going as if nothing ever happened. Also, even without the sun's energy, the Earth itself is a roiling ball of molten metal on the inside; it has tons of internal heat. Places like Iceland and Yellowstone could still be colonized, even after the atmosphere freezes and snows to the ground. The rest of us could eke out a living underground. Ultimately, we'd be living on the frozen surface of a thin crust covering a giant ball of lava. It just wouldn't make sense to freeze to death under those circumstances. We'd figure it out.



And of course, we are talking about billions of years in the future. If by then we'd mastered the science of contained fusion, then we wouldn't need the sun anyway. There's enough fusion fuel freely available in the atmospheres of Jupiter, Saturn, Uranus and Neptune to support billions of people for tens of billions of years without the sun, and with fusion powered spacecraft we could reach the nearest stars in decades rather than millennia.

So cheer up! The end isn't near, nor is it inevitable.