What If The Sun Never Went Down? | Unveiled

What If the Sun Never Went Down?

Without the sun, life on Earth would never have been able to flourish and the solar system as we know it would not exist. But the sun can also be deadly. The radiation it emits is a leading cause of cancer, it’s slowly cooking our planet into a warmer and warmer place, and in a few billion years’ time it’ll expand, scorch and consume many of the worlds which orbit it. But, just how dangerous would it be if the day/night cycle didn’t exist? If we were never able to take a break from our nearest star?

This is Unveiled, and today we’re answering the extraordinary question; what if the sun never went down?

Plenty of objects in space experience tidal locking, which is when one side is constantly facing whatever celestial body that object is orbiting. The moon, for example, is tidally locked to the Earth, meaning that the same side is always looking down on us. This doesn’t mean that the moon doesn’t rotate, it does, just at the same speed as it orbits the Earth, in what’s known as “synchronous rotation.” All of which means that there’s sometimes some confusion over the far side of the moon. It’s often referred to as the dark side of the moon, but it isn’t in constant darkness. It still turns to face the sun and turns away again, it just never faces the Earth. Still, because of how relatively slowly it rotates, most of the moon sees a regular cycle of two weeks of sunlight followed by two weeks of darkness. It’s one of many reasons why humans would find it incredibly difficult to actually live on the moon.

There are other moons tidally locked to their planet elsewhere in the solar system, too. Titan is locked to Saturn, for example, and Pluto and Charon are locked to each other. Mercury is the only planet tidally locked to the sun, though, but it’s not at a 1:1 ratio… which means that even across the Mercurian sky the sun does sometimes go down. Elsewhere in the universe, it’s thought that some red and white dwarf stars could have tidally locked planets within their habitable zones. These planets would hypothetically host temperatures suitable for life, it’s just that sunlight would only ever reach fifty percent of their surface.

Back on Earth, choosing a life where the sun never goes down will probably never be an option for us. Though half of our planet is in light at any given time, we can’t follow the sun across the sky. This is because daylight only lasts for twelve hours on average here, but the fastest non-stop flight around the world (accomplished by the legendary pilot Steve Fossett in 2005) was completed in sixty-seven hours. That’s almost three full days, meaning multiple periods of light and dark. The closest we can get on Earth to constant daylight, without changing something fundamental about the way the planet works, is at either the north or south pole. Because of their extreme position, the poles experience months-long periods of uninterrupted sunshine... but even at both ends of the Earth, night does eventually come.

So, scientifically speaking, the sun never going down just isn’t possible here. But what if it was. What if, say, the Earth’s orbit were to change, we became tidally locked to the sun, and for whatever reason those on the sunny side of the planet couldn’t escape it?

Right away, the biggest threat would be the radiation. Solar radiation is already incredibly dangerous and is the leading cause of all skin cancers, affecting hundreds of thousands of people every year. With no night to provide respite from the sun, then, the cancer rates would certainly surge. Endless light would wreak havoc on our bodies in other ways, too, not least our sleep patterns. Countless studies have been carried out on long-haul pilots and astronauts to determine how their jobs affect their circadian rhythms, but now everyone would be forced through an even more extreme change.

In fact, the perpetual daylight would probably become unbearable after just a few days. One quite disturbing study, published in the “Current Biology” journal in 2016, saw mice subjected to six gruelling months of constant light. The mice got so stressed under these conditions that they reportedly exhibited various symptoms linked to a number of diseases, including bone and muscle wastage. The good news was that the effects were found to be reversible… but if, in this hypothetical world, the sun literally never went down, then it’s hard to imagine that humanity - or much of life at all - could survive in such a place. Physical sickness and mental strain could well take hold before even the increase in cancers became apparent. It’s one of the reasons why astronauts on the ISS keep a simulated day/night cycle: because NASA knows how crucial our body clocks are to how well we can function.

Of course, such a dramatic change wouldn’t just be hard on humans, but hard on all animals which rely on the fact the sun will rise and set every day. Without the cover of night, some animals wouldn’t be able to hunt, and others wouldn’t be able to hide. Without the cooler temperatures at night, many species would struggle to survive and, over time, no doubt we’d see other species adapt. In much the same way as various creatures live in permanent darkness on Earth as it is - in caves, or at the bottom of the sea, for example - we’d see animals physically change to cope with the endless sun. Constant sunlight would be especially devastating for plants, too, many of which would burn up very quickly… because even those which are adjusted to hot climates, like cacti, need the cool of the night. All the world’s crops, then, would wither, dry out and die… extreme desert conditions would set in, and fires would spark at a moment’s notice tearing through what remained of the forests and woodland.

The situation does change somewhat if there’s free movement between the light and dark sides of an Earth that’s tidally locked to the sun, however. In this case, it would still be bad news for plant life, which while being scorched and dried out on one side of the world, would wilt and die out on the other through lack of sun. For animals and humans, though, there’d be the possibility of regular migrations from the light into the dark and vice versa. In this hypothetical scenario, it would be best to form settlements all along the border between the light and darkness… that way you could move in and out of the sunlight, to effectively create your own days.

Failing that, the best course of action would be to head underground. Or else to create sweeping shelters big and thick enough to cast large areas of permanent shade and to totally shield from radiation. Inside caves and tunnels, we could simulate a day/night cycle with artificial lights turned on and off at set times. Perhaps we could even grow plants and rear livestock underground with the correct equipment. In this case, vitamin supplements - to replace the nutrients we now wouldn’t be getting from the sun - would be vital, and UV lights could mimic sunlight through the darkness. It feels counterintuitive, but the best way to deal with permanent sun could well be to permanently avoid it. Such an environment could ultimately breed sprawling, subterranean cities, which would be cooler, more controlled, and safer for all. If we couldn’t get under the Earth’s actual surface, then we’d need to build a new layer all around the planet - a worldwide roof, of sorts, to provide life with the cover it needs.

Whatever the case, it’s clear that this is an alternate reality we should be glad we’ll never get to see. Everyone loves it when the sun comes out, but it’s just as important that it always sets. Because that’s what would happen if the sun never went down.