# Theoretical Extinguishing of the Sun with water!

I fear that I am way out of my depth here, being a mere mathematics student but anyway....

We have been asked by our mathematical modelling lecturer to calculate the quantity of water required to extinguish the sun. I'm pretty sure that the exact physics and processes of the sun are not required just the main properties, equations, etc..

It must be totally obvious that I have absolutely no knowledge of astrophysics at all and am just hoping that someone could possibly advise me on what I need to include for a reasonable answer.

Cheers Chris

## Answers and Replies

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NateTG
Science Advisor
Homework Helper
Mister Nonsense said:
I fear that I am way out of my depth here, being a mere mathematics student but anyway....

We have been asked by our mathematical modelling lecturer to calculate the quantity of water required to extinguish the sun. I'm pretty sure that the exact physics and processes of the sun are not required just the main properties, equations, etc..

It must be totally obvious that I have absolutely no knowledge of astrophysics at all and am just hoping that someone could possibly advise me on what I need to include for a reasonable answer.
Because the sun isn't powered by oxidation, but by nuclear reactions, putting water on the sun isn't going to slow it down much at all, in fact, adding *LOTS* of water would probably make the sun brighter.

That said, water extinguishes fire by two methods: cutting off oxygen, and cooling things down. You could try to approximate how much water at 0 degrees C it would take to cool the sun down to 100 degrees C.

Alternatively, you could look up (use e.g. google) the amount of energy that the sun produces, and figure out how much water boiling off per second would be required to consume that amount of heat.

HallsofIvy
Science Advisor
Homework Helper
You will need to know, or look up,

1) The total amount of heat in the sun.
You might be able to get that by using the average temperature, the volume of the sun, and its "heat capacity".

2) How much energy is required to vaporize a certain amount of water.
You probably do NOT need to worry about getting the water TO the boiling point since the sun is so much hotter than that!

3) Once you have those, the rest is just arithmetic. How much water do you need to account for all the heat energy in the sun?

tony873004
Science Advisor
Gold Member
Since the Sun radiates away its heat, and radiation is the least efficient of the heat transfer methods, placing the Sun in a tub of water would draw heat away from the Sun much quicker. But like said earlier, the Sun is not like fire here on Earth. The Sun shines by fusing hydrgen into helium by the immense pressure at its core. Adding anything to the Sun is sure to increase that pressure and make it burn even brighter. And (just a guess...) since water is 2 hydrogen atoms, they'll probably get stripped away from the oxygen by the high heat so you'd only be adding more fuel to the fire + an oxidizer.

You will never be able to extinguish the sun with water. Adding water not only increases the amount of hydrogen fuel available to the star, but also increases the mass, hence increasing the pressure in the core of the star and thereby also increasing the rate at which nuclear fusion occurs

Labguy
Science Advisor
Pyrovus said:
You will never be able to extinguish the sun with water. Adding water not only increases the amount of hydrogen fuel available to the star, but also increases the mass, hence increasing the pressure in the core of the star and thereby also increasing the rate at which nuclear fusion occurs
Use above answer for your math lecturer. He might be thinking of some neat math on heat transfer, but the physics part would be just like Pyrovus said.

its not physically possible to extinguish the sun with water. In fact, its not physically possible to extinguish the sun at all, short of causing it too disperse into space, but good luck with that. I think your math professor took the end to Spiderman 2 a little too seriously.

Not only is it impossible.... please remember that when a Star novas that is not unusual to find Oxygen and Hydrogen in its remnants. Rho Cas is a very good example of this.

It would be impossible to extinguish the sun using water. All of it will simply get evaporated long before it reaches the corona. Dumping the sun into a black hole and calculating how much time it takes for the balck hole to devour it is a better, and exceedingly more relevant, problem! :D

Astronuc
Staff Emeritus
Science Advisor
I think a simple (and very imaginary) problem like this would be asking for a quantity of water (at some temperature - e.g. 0°C) that would be required to bring the temperature below the threshold for fusion - in this case for the CNO-cycle.

Obviously, it will be a large mass - on the order of the mass of the sun - and anything that large with H and O might itself have sufficient mass to induce fusion or the conditions for fusion.

Astronuc said:
I think a simple (and very imaginary) problem like this would be asking for a quantity of water (at some temperature - e.g. 0°C) that would be required to bring the temperature below the threshold for fusion - in this case for the CNO-cycle.

Obviously, it will be a large mass - on the order of the mass of the sun - and anything that large with H and O might itself have sufficient mass to induce fusion or the conditions for fusion.
It is not possible. That mass of water would collapse like the gas cloud that formed the sun, the intense pressure would cause temperatures to rise in the core, causing the water molecules to break down into component atoms which would become ionized. Voila we have a new star. It cannot be done. The problem is a worthless excersize in algebra that has no connection to reality.