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What would happen if the sun disappeared?

As you may already know, there is two ways for a star to die. The first one is for the average stars, the become red giants and then white dwarf. As for the massive stars, the become a red supergiant before being supernova and they end in either a black hole or a neutron star. For the sake of our experiment we will think of a third scenario, the total disappearance of the star in one instant.


For the supernova, our planet would be exposed to an explosion of about 20 billion billion billion megatons of TNT, or  tons of TNT, which is more than 17.5x Tsar Bombas. It's hard to imagine surviving after being hit by such an explosion, so let's focus on another option.

Our second option if that of the white dwarf. A white dwarf is created when a small to medium-sized star finishes consuming all the hydrogen available to it. The star collapses onto itself, revealing only its core, which becomes the white dwarf. While this scenario is the one who will happen to our sun, it will not happen until billions of years so let’s skip to our final option.


Finally, the last scenario we can imagine is if the sun were to disappear overnight without waiting billions of years before extinguishing itself. The most direct consequence for us would be the absence of light. It would be night on the entire surface of the globe, and we wouldn't even be able to distinguish the moon in the sky because it normally reflects sunlight.


The light emitted by the sun takes 8 minutes and 20 seconds to reach Earth, so if the sun were to disappear, we would have to wait 500 seconds.


Furthermore, it's not just light that takes 500 seconds to travel from the sun to Earth; gravity does too. It's a concept we tend to forget, but if the sun were to disappear, the sun's gravitational influence would still affect Earth during this short period of time. To put it simply, Earth would keep orbiting around an empty space for those 500 seconds before continuing into a straight trajectory in outer space. This implies that a collision with another massive celestial object would be possible, even very likely, which once again is not very good for our survival.


Here's an explanatory diagram of the orbit of Earth mentioned above:

But come on, nothing can be all white or all black right? Because there could be some advantages. Earth would no longer be threatened by solar flares and eruptions, and astronomy enthusiasts would rejoice because observation would be greatly facilitated: no more light pollution and pitch black nights! Although those might be cool, they are pale pros for some serious cons.


Would the disappearance of the sun mean the end of humanity and all life on Earth?


For humanity, we can undoubtedly affirm that the answer to this question is yes. Just as reminder, without the sun, the temperature on the Earth's surface would drop below that of ice ages. The only way for humans to survive in these conditions would be to burrow deep underground where the temperature would be more acceptable for humans. But in these depths and without sunlight, it would be impossible to grow crops. Humans would have to rely on non-perishable food sources, and this could not last forever.


As for other forms of life, the answer would not be as straightforward because there are many animal species that live either underground or in the depths of the oceans, where the sun has no influence because its rays do not reach such depths. If we take, for example, a fish living at the bottom of the Mariana Trench, it probably wouldn't notice the disappearance of the sun because it is likely not sensitive to light (and thus not sensitive to the lack of light) or to the heat it provides. Ultimately, water and everything will froze leading those species to meet their end.


Overall, while the disappearance of the sun remains firmly in the realm of science fiction, exploring such scenarios enriches our understanding of the interconnectedness of Earth and the cosmos. It serves as a reminder of the fragility of life and the preciousness of our sun's warmth and light.

To conclude, we can easily affirm that the loss of our sun would bring both advantages and disadvantages, even though the advantages would not outweigh the disadvantages. Fortunately for us, our sun is not at risk of disappearing for several billion years, and no cases of sudden star disappearance have been recorded to this day. So, you can rest easy, whether under a blazing sun or not.


Mathéo Lourdelle

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