Thursday, 16 January 2014

(Primary Science) How does the Sun burn when there's no oxygen in outer space?


We know that burning requires oxygen. Burning is a chemical reaction. But what happens in the Sun is not a chemical reaction. It's a nuclear reaction or more accurately nuclear fusion. So we can't really say that “the Sun burns”.

Nuclear fusion occurs in the Sun... 

If you are really curious to know why, the next paragraph is the explanation. This is difficult Science which is not required in Primary level. I've tried to simplify it as much as possible. If you can't understand it, don't worry. Just know that it's not a chemical reaction that happens in the Sun. No oxygen is involved.

Nuclear fusion is not burning...

The Sun consists of very dense and hot plasma. Plasma is a state of matter other than solid, liquid and gas. The plasma in the Sun is mainly charged hydrogen. The very dense and hot hydrogen undergoes nuclear fusion to become helium. In nuclear fusion, some of the mass of hydrogen becomes energy. That is why nuclear fusion gives out a lot of heat and light.



Some of the mass becomes energy! 


Now, mass and energy are two different things as you have learned. How can mass become energy? It sounds strange but it happens in nuclear reactions.

Meanwhile, enjoy this video about the Sun.

https://www.youtube.com/watch?v=AX2sH0dOgMg

Try these questions before you check with the answers.
1. (a) What gas in the air is needed when a fuel is burned?
(b) Another name for burning is combustion. Is combustion a chemical reaction?
(c) What forms of energy are given during combustion?
2. (a) From the passage, is nuclear fusion a chemical reaction?
(b) Complete the statement that is about nuclear fusion.
___X___ --> __Y__ + energy
(c) What forms of energy are given off by nuclear fusion?

Answers: 1. (a) Oxygen (b) Combustion is a chemical reaction. (c) Heat and light 2. (a) Nuclear fusion is not a chemical reaction. (b) X: hydrogen, Y: helium (c) Heat and light 

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