I have strange thoughts in the shower! I guess everybody does:

– What if you could drill a tunnel through the whole planet and then jumped down this tunnel; would you be able to get out the other side?

– If gravity suddenly increased would airplanes fall out of the sky, or would it compress the air in such a way that airplanes could keep flying?

– Would humanity survive if the sun went out?

Let’s talk about the last one… and I don’t mean what would happen if the sun explodes, but what would happen if someone, maybe a powerful Alien stole or switched it off.

This is what scientists call a mental experiment. You don’t need fancy equipment to do science, just your imagination!

If the sun suddenly disappeared we wouldn’t notice immediately. As you may know the light from the Sun needs around 8 minutes and 18 seconds to reach the Earth, so at first we wouldn’t have a clue the sun wasn’t there.

The gravitational force of the Sun on the Earth would also disappear, but we would again need those 8 minutes and 18 seconds to notice, because the gravity force travels at the speed of light. After that the Earth would fly out in a straight line tangent to wherever it was in its orbit covering about 30km every single second.

Night everywhere


After the first 8 minutes it would suddenly become night everywhere. Even in the places where it was already night there would be changes and you would notice as the Moon’s light is just the reflection of the Sun’s one, therefore the Moon would just vanish in the sky.

At this point everybody would be terrified and we would suffer some chaos so we probably wouldn’t notice that the planets would last a bit longer, shining in the sky.

Mars would continue orbiting and reflecting light from a Sun that no longer existed for 8 minutes after we notice the Sun had disappeared, an hour later Jupiter would follow, Saturn would need around 2 hours to fade out, Uranus 5 and Neptune could even need 8 depending on where they were located in that situation.

With no moonlight or sunlight, the stars from the universe would be our only source of visible light from space. That would make an amazing sky, but the Milky Way only contributes about as much light as 1/300th of a full Moon… so it doesn’t produce enough light for us to see anything.

But don’t worry we would use the electricity and the fossil fuels and we would turn on the lights in the cities as we do every night.

chicago without sun


The plants would stop performing photosynthesis so they wouldn’t be able to inhale carbon dioxide and exhale oxygen. Fortunately all of us humans breath in about 6 trillion kilograms of oxygen every year. But our atmosphere contains 1 quintillion kilos of oxygen, so even without photosynthesis, and including all the animals that consume oxygen, it would take us a thousand years to decrease the levels of oxygen enough to start feeling it. We could also create more oxygen the ISS style, through water electrolysis.

The plants would die in days or weeks but giant trees would last a few years thanks to their sugar reserves if they don’t freeze.

With the bottom of the food chain dead, most animals would die quickly and we would have to figure out a new food chain based on non-photosynthetic plants.


It’s freezing outside


Right now, the average temperature on our planet is about 15º Celsius. Without the sun the temperature will slowly decrease. It won’t freeze instantly as a mug of hot tea doesn’t freeze instantly when placed in the freezer, but it will certainty cool down.

By the end of the first week without the Sun, the average surface temperature across Earth would be freezing zero Celsius

But, by the end of the first year without the Sun, the average global surface temperature would be -73º C. That’s worse than Norilsk in Siberia where you can enjoy -58ºC.

At that point, the surface of the oceans would freeze. But only the surface, and as ice is a good insulator liquid water would still exist at the bottom of our oceans, insulated from space and warmed by the Earth’s interior. Humans could live in submarines in the deepest and warmest parts of the ocean.

But a nicer option would be to move to geothermal areas:

– Tuscany in Italy

El Tatio in the Andes Mountains

– Beppu in Japan

– Yellowstone in USA

– Haukadalur in Iceland

– North Island in New Zealand (in the picture below)

New Zeland

The inside of the Earth is hot. 20% of this warmth came from the fact that when the Earth formed, mass crushed so tightly in the middle that the pressure liquefied rock. The other 80% of Earth’s internal heat comes from that fact that deep in its core, radioactive elements decay, providing the energy needed to keep the Earth’s core at 5000º C.

It’s snowing oxygen

In the next 10-20 years the air would became liquid. The air would literally become cold enough for the gasses that make it up to condense, or form clouds and precipitate, first as rain, and then as it got colder and colder, eventually, as snow. In order to survive, a family would have to go outdoors in a special suit and scoop up a pale of just the oxygen snow, bring it back in, and place it over a fire to warm and allow them to breathe.

Or they could maybe just be warmed and powered by nuclear fuel. Sure it’s not a green solution, but considering plants are dead it’s not very green outside anyway.

Lucky for us it seems very unlikely the sun will disappear at least in the next 5 billion years. So, I don’t know you, but after this mental experiment I really need to go outside and feel the sunshine on my skin.

Posted by Shedka

Listen to the whole show here:     Part 1     Part 2


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