When the Sun Disappears

Let’s imagine a scenario where the Sun suddenly disappears. This isn’t something that could actually happen, as the Sun is set to die billions of years from now by expanding and consuming Earth, not simply vanishing. Matter and energy don’t just disappear—it’s almost impossible for something like the Sun to just cease to exist. But for the sake of a thought experiment, let’s explore what would happen if the Sun did disappear.

The moment the Sun vanished, we wouldn’t know right away. Light from the Sun takes about 8 minutes and 20 seconds to reach Earth, so we’d continue to see the Sun in the sky for a little over 8 minutes after it was gone. At that moment, chaos and panic would likely begin to spread as people realized the Sun was no longer there.

Not only would the light from the Sun take time to reach us, but the Sun’s gravitational pull would also take 8 minutes and 20 seconds to stop affecting Earth. Once the Sun’s gravity was gone, Earth would no longer orbit the Sun but would instead move in a straight line through space, away from where the Sun used to be.

Interestingly, even after Earth knows the Sun is gone, other planets like Jupiter would still seem to orbit and reflect sunlight for about 30 minutes longer. Eventually, though, these planets would also stop reflecting sunlight, and the light from the Sun would disappear from the sky entirely. The only visible light left would come from stars in the Milky Way, which would be dim, contributing only about 1/300th the light of a full moon.

Without sunlight, photosynthesis—the process by which plants convert sunlight into energy—would stop immediately. Photosynthesis is responsible for 99.9% of the natural productivity on Earth, so this would have massive consequences. Without photosynthesis, plants couldn’t produce oxygen or absorb carbon dioxide. Fortunately, the Earth’s atmosphere contains a vast amount of oxygen, so humans wouldn’t run out of it for thousands of years, but the plants would start dying within days or weeks due to the lack of sunlight. Larger plants, like giant trees, could survive longer because they have stored energy, but they would eventually freeze as the Earth cooled without the Sun’s warmth.

Currently, the Earth’s average surface temperature is around 14 to 15 degrees Celsius. Without the Sun, the Earth would lose heat rapidly at first, and then more slowly over time. By the end of the first week, the average global temperature would drop to freezing, 0 degrees Celsius. Although humans could survive for a while by using artificial heat sources, by the end of the first year without the Sun, the Earth’s average temperature would plummet to -73 degrees Celsius.

In this freezing world, the best places to live would be near geothermal areas like Yellowstone or Iceland, where Earth’s internal heat could provide some warmth. Earth’s internal heat comes from the energy released during its formation and from radioactive decay deep within its core, which keeps the Earth’s interior at around 5,000 degrees Celsius.

Without the Sun, most people would not survive the first year unless they lived in one of these geothermal areas or in underground shelters powered by nuclear energy. Eventually, the atmosphere would become so cold that gases like oxygen and nitrogen would condense and fall as snow. The oceans would freeze over completely, but liquid water might still exist at the bottom of the oceans, insulated by miles of ice above and warmed by hydrothermal vents on the ocean floor.

Life near these vents, such as extremophiles—microorganisms that thrive in extreme conditions—would continue to survive without sunlight. These organisms rely on chemosynthesis, a process where they convert chemicals from the Earth’s interior into energy, rather than using sunlight. They would continue to live, completely unaffected by the Sun’s disappearance, possibly not even aware that the Sun ever existed.

This scenario shows that while most life on Earth’s surface would die off, some forms of life could continue to exist deep in the oceans, and the Earth itself would remain a kind of spaceship, carrying life through space for billions of years. Over time, Earth could travel across the galaxy, potentially encountering other stars, and maybe even find a new star to orbit, warming up and allowing life to thrive once again.

In the distant future, intelligent beings might uncover what was left of our civilization and learn about our history, possibly even discovering a something like this one, documenting Earth’s journey through the cosmos after the Sun disappeared.