How Large Would a Bucket Have to be to Put Out the Sun?

The sun is often referred to as a big huge ball of fire, just casually providing us with warmth, light, and basically, life. Imagine putting it out!

How large would a bucket of water have to be? Your initial thought might be an incredibly off-the-scale massive bucket full of water. And that would still be too small. You know why? Because no amount of water will ever be able to put out the sun! 

In fact, throwing a bucket full of water at the sun would just make it burn brighter because the water would essentially serve as more fuel. But doesn’t water put out the fire? Why would it fuel it up even more? 

How large would a bucket have to be to put out the sun

Well, the sun isn’t a fire, exactly. Fire, such as candles, or fireplaces, and others, are chemical combustion. The sun, on the other hand, is nuclear fusion.

Basically, the sun is more of a giant hydrogen bomb, constantly going off, instead of a giant campfire in space. And as water contains hydrogen, you would just be feeding it up! 

Let’s look at the explanation in more detail. 

Fire, and Chemical Combustion

Whenever you see fire, like a campfire, or a fireplace, or a candle, what’s causing it is chemical combustion. Combustion doesn’t always produce actual flames of fire, but they’re one of the main indicators that combustion is taking place. 

But what is chemical combustion, exactly? 

It is essentially a chemical reaction between a fuel (which is what the fire consumes), and an oxidant (usually oxygen). However, these two elements alone aren’t enough to start the combustion, a hot temperature is required to initiate it. 

Once the fire is burning, it produces enough heat to keep the combustion going, and as long as it has enough fuel and an oxidant, it will keep going and going and going.

In fact, only a tiny spark is needed to initiate combustion, and fires can then grow to massive sizes, making them almost unstoppable. 

But why do you need a hot temperature to start the fire up? 

The energy released during combustion, which is what makes a fire bright and hot, comes from the forming of new chemical bonds, which happens thanks to the chemical reaction between the fuel and the oxidant.

But for these new bonds to be formed, the existing bonds between atoms need to first be broken down. And to break these bonds down, you need energy. The easiest way to provide this energy is through a high temperature, as it provides thermal energy: heat. 

For example, when lighting a campfire, you will first light a match. And when you light a match, you’re applying friction to its surface with a fast movement, which releases heat, and that activates the chemical combustion!

The match then provides a small flame, which releases heat, and that heat is what kick starts the chemical combustion in the campfire, thanks to the combination of fuel (the wooden logs), and an oxidant (oxygen from the air). 

Water can put out a fire because of two reasons

  • Water absorbs the heat from the fire and, therefore, takes away the heat that enables chemical combustion from occurring. So the fire dies. 
  • Water covers the fire and prevents the oxygen from reaching it, so it smothers it. This interruption of the chemical reaction between fuel and oxidant, causes it to die down. 

The Sun, and Nuclear Fusion: 

We know that water can put out a fire. But the sun is not a fire with chemical combustion, it’s nuclear fusion. This means it works in a completely different way.

Let’s start by looking into what nuclear fusion is. 

Nuclear fusion is a reaction, in which two or more atomic nuclei are being combined so that they end up forming one or more different atomic nuclei.

The difference in mass that this combination produces often releases large amounts of energy, that can be seen as heat and light. This is the process that powers stars, such as the Sun. They’re like a hydrogen bomb that is constantly going off. 

But how do the atomic nuclei combine? Why do they? 

The reason why they combine is that they are being pushed so close together that they end up sticking to one another, and become something new entirely.

A very high temperature can cause the atomic nuclei to be pushed that close together, but when it comes to the nuclear fusion of stars, the main thing driving them to combine is high pressure.

Pressure and high temperature are linked, and ultimately they both play a part in nuclear fusion. But in stars, pressure has an enormous force, due to the gravitational pull of the star itself. 

Basically, a star, like the Sun, is huge. And that amount of mass is so big, that the gravitational force it has, also causes it to crush itself. It is like it’s dragging itself inward, constantly.

This causes an enormous amount of high pressure, and high temperature, within itself. And as a consequence, the atoms that it is made out of, begin to react in a nuclear fusion. This then produces a huge amount of energy, which in turn also keeps it going. 

What happens if you throw water on the sun?

Okay, so the sun is burning bright and hot, thanks to nuclear fusion. But what happens if you were to throw water on it? Why wouldn’t that put it out? Let’s explain! 

As the sun isn’t a chemical combustion, like fire, water doesn’t cool it down or smother it out. Water can’t put out the Sun.

Instead, water would simply be adding more hydrogen atoms, which would combine with the rest through the nuclear fusion, and would end up adding to the Sun’s mass. 

Water would basically be adding more fuel to the Sun, as it would be giving it more atoms to combine together, increasing the mass, and therefore increasing the gravity, which increases the pressure, which increases the nuclear fusion...and so on.

To put it simply, water would make the Sun burn brighter and bigger, instead of ever putting it out. 

So instead of figuring out how large a bucket would have to be to put out the Sun, you can instead try to figure out how large it would have to be to visibly increase the brightness.

After all, a human-sized bucket of water is incredibly tiny compared to the mass of the Sun, and we can safely say that it would not have any effect whatsoever. It’s simply too insignificant in scale. 

A bucket large enough to cause the Sun to increase its brightness by just 1%, would have to hold enough water equivalent to the mass of the Earth, multiplied by 800. A pretty massive bucket of water. 

Gordon Watts