What if the Sun Turned Off?

The sun is vital for life on Earth. It is needed for complex life.

Sunlight acts as a food source for plants, which use a process called photosynthesis to survive. These plants are then eaten by creatures, which are eaten by other creatures, so on and so forth creating the world’s diverse forms of life on Earth.

Without sunlight, plants would rapidly die off, and so would all other animals that feed off of these animals.

In today’s article, we will be exploring the hypothetical situation of the sun “turning off,” how it would change the world, and how humans could survive as long as possible.

Why Can’t All Animals Eat Each Other?

Humans, animals, and bugs all let out heat. Heat is a form of energy. When you eat another animal, you can never receive 100% of the energy that animal has stored in themselves because they are letting go of heat.

Doing so would also require you to eat every last little bit of the animal. This is simply not possible.

There are always leftovers for micro-organisms to decompose on the animal. This is why the sun is vital for life on Earth- we must have a renewable energy source to power the flow of life!

No Gravitational Pull

If the sun were to “turn off,” but its gravitational mass still exist, we would still fly around the solar system.

If the sun were to disappear entirely, there would no longer be a large center mass as the center of the solar system!

Our planet along with all other planets & objects in the solar system would fly off each into its own direction. It is unlikely that we would collide with any other planets but it is a possibility.

We would become a “rouge planet,” which is a planet with no sun or solar system. The planet would wander the universe for a very long time before colliding with another object or joining a new solar system.


Without sunlight, it would be very unlikely that we can see the moon. With special technology we may be able to find the moon, or with the stars, but even then the moon would be extremely dark.

The way we can currently see the moon is sunlight reflects off of the moon and goes to Earth. Without sunlight, there is no light reflecting off of the moon, and so we could no longer see it!

Earth Effects

Scientists estimate that without sunlight the Earth’s temperature would reach 0F by about one week. This temperature would for the most part be consistent across Earth, except in areas with geothermal heat, such as Iceland.

Within thousands of years, the Earth’s atmosphere would collapse and harmful radiation would pour into Earth.

Within days the majority of life would be dead. A few tough animals such as polar bears may be able to survive longer, and certain powerful trees could survive for hundreds of years in a permanent winter state, but they would all die eventually.

The ocean would freeze over one week in. We would turn into an ice planet, however beneath the surface there would still be water.

The center of the Earth is actually very hot and may not even be solid. Certain areas with volcanic activity may release heat that allows for micro-organism life in the Ocean, but within thousands of years the Earth would get too cold for even these organisms to thrive!

Micro-organisms are highly resistant to extreme environments, and can even survive in outer space! They may not be thriving & reproducing, but they can enter a dormant state and then when conditions allow begin living again.

It is very likely that the Earth would be filled with micro-organisms in a type of “hibernation state,” waiting until they can find a suitable area to thrive in again (if ever again).

Human Survival

Within the first week, many humans would die off. Humans could delay their death by remaining in warmer areas such as Iceland.

Iceland is generally quite cold, but it is warmed up from geothermal power which means that heat comes from the Earth, and not the sun. The entire Earth would begin cooling down, including areas like Iceland, but Iceland for example would actually be warmer than other areas!

These humans that are able to survive brutally cold temperatures may be able to survive a month, or two, but at the one year mark almost all humans would be dead.

Going Underground

If humans were prepared for this catastrophe, it is possible that a few inventive humans may be able to band together to survive!

The solution would be to go underground. Underground, we could leverage geothermal power. We also release lots of heat just by existing, and technology such as computers release lots of heat as well which could keep these areas warm.

Surviving underground would pose several challenges though:

Vitamin D

Humans collect Vitamin D from the sun or through supplements. Vitamin D is responsible for strong bones and a healthy mood.

Miners that spend lots of time underground can develop “rickets,” which is a bone problem. People with not enough Vitamin D may have bendy bones, weak bones, or bones that easily break.

People that lack Vitamin D also tend to have depression and other mood disorders.

If humans were to survive underground, we would have to find a way to get Vitamin D because in this scenario it would be almost as important as food.


We may run out of good air underground. The best way to combat this is to somehow create an experimental plant that can thrive underground.

Trees collect carbon dioxide and turn it into oxygen. Too much carbon dioxide and too little oxygen causes hallucinations, brain problems, and eventually death.

We would need a machine that can turn carbon dioxide into oxygen, or plants that can survive underground.

Food Sources

Finding food underground would be near impossible. We could in theory create an entirely new ecosystem, but this would require decades of planning and experimentation.

In theory, it is possible to create a renewable light source powered by geothermal or water power. This light source could then fuel plants via photosynthesis, which could be eaten by animals that we want to eat.

We would most likely become vegans and just eat the plants.

This problem would be the hardest of all to solve. We can’t eat other animals forever for reasons described above. Vitamin D, oxygen issues, and water issues could be solved with technology. Sustenance issues would be a bit harder to fix.

The Most Likely Scenario

The most likely scenario if the sun “turned off” is that we would all die. Some humans could survive for year’s underground, and they would suffer horribly until their death.

They could have a heat source, a large supply of food and water, and air filters, but none of this is renewable and they would also be lacking Vitamin D.

With the right preparation and lots of collaboration, in theory a very small “tribe of humans” could find a way to survive underground, but it would not be fine living!


We hope you enjoyed this article. Thanks for reading! :)
-Wildlife X Team International

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