Would you like to survive if the sun dies? (When is actually more like it.) I would. Of course, I’ll be dead long before then, but in theory, anyway.

The sun will make Earth uninhabitable long before it completely burns out. Is it possible that our tools and technology will be so advanced in a couple hundred million years that we can “maintain” the sun or construct other ones as need be? Anything’s possible given enough time, I suppose, but other workarounds are likely more realistic.

In “How to Survive Doomsday,” an excellent Nautilus essay, Michael Hahn and Daniel Wolf Savin look at the daunting task of outlasting our star. An excerpt:

In a paltry 500 million years or so, no humans will remain on the surface of the Earth—at least, not outside of some hypothetical controlled environment. And things get worse from there. After the atmospheric CO2 is gone and no longer able to regulate Earth’s surface temperature, things will start to get very hot. In about a billion years, the average surface temperature will increase to above 45 degrees Celsius from the current 17 degrees Celsius. Important biochemical processes turn off at temperatures above 45 degrees Celsius, leaving most of the planetary surface uninhabitable. Animal life will need to migrate to the cooler poles to survive; but by 1.5 billion years from now, even the poles will be too hot. Not even cockroaches will survive.

Now, there are a few things we can do to stay our execution. We could, for example, move the Earth’s orbit. If we fired a 100 km wide asteroid on an elliptical orbit that passed close to the Earth every 5,000 years, we could slowly gravitationally nudge the planet’s orbit farther away from the sun, provided that we don’t accidentally hit the Earth. As a less precarious alternative, we could build a giant solar sail behind the Earth with enough mass to drag the planet away from the sun. Such a sail acts like a kite, where the photons from the sun are the wind and the gravity between the solar sail and the Earth acts as the string. The sail would need to have a diameter 20 times that of the Earth but a mass only about 2 percent that of Mt. Everest, a mere trillion metric tons. Strategies like these could, in principle, keep the Earth in the habitable zone until the sun expands into a red giant. (If some other civilization has already built such a large solar sail, we could detect it using the same photometric techniques that are currently used to find exoplanets.)

Another survival choice is more complicated—or simpler, depending on your perspective. The future Earth will actually be a pleasant home for non-biological life—better than it is today. For one thing, the brighter sun will provide more abundant solar power. The space weather will also be nicer. The sun is a dynamo spinning on its axis about every 24 days, generating giant magnetic storms that disrupt communication networks, overload power grids, and damage orbiting satellites. Robots today need fear that their circuits could be fried by a solar storm, such as the large solar storm in 1989 that caused a power failure across most of Quebec. Currently, such storms are estimated to occur about once or twice per century. But as the sun ages, this rotation slows down and the magnetic storms will abate.

Given these facts, we humans might simply decide to upload ourselves into machines, which would be relatively comfortable on the dystopic future Earth.•