Nuclear fusion in the sun?

Question

In science class, my teacher told us that nuclear fusion in the sun occurred in the core. He said, "Nuclear fusion in the case of the sun is when two hydrogen protons smash together to create deuterium, which has one neutron. Then the deuterium atom smashes together with another hydrogen proton to make Helium-3. Then two Helium-3 smash together to make a Helium-4."

First, is this correct?
Second, can nuclear fusion in the sun still occur with a hydrogen proton and a hydrogen neutron? Will it emit as much energy?


Please keep in mind that I'm an eighth grader, and that the explanation was for eighth graders to comprehend.

Answer 1

Well, it depends how much details you want.

What your teacher was describing is the proton-proton chain and he was leaving out all the details that are very important to nuclear/particle physics. This is probably a good idea or else he would have to explain what an anti-electron (positron) and an electron neutrino are... but since you are a smart eight grader, it is only fair that you take a look at the full reactions.

Anyway... the pp chain is only one of several possible reactions (although it is the most important one in the sun). If you want to know how energy release from fusion works in stars in general (where different temperature/pressure regimes favor very different reactions over the pp chain), please look at

http://en.wikipedia.org/wiki/Stellar_nucleosynthesis

for a more detailed answer.

As for the second part: there are no "hydrogen-neutrons". Hydrogen is one proton plus one electron. Since the material at the center of the sun is fully ionized, there are only free protons and free electrons. The neutrons bound in deuterium and tritium are very important, though.

Answer 2

Your teacher is using simplistic ways to tell you about fusion in the sun. Atoms of hydrogen do smash into into each other to create helium, they fuse together because of the tremendous pressure and heat at the core of the sun. Four atoms of hydrogen fuse to form one atom of helium, the weight of the helium atom is a little less than than the combined weight of the four hydrogen atoms that were fused together, the mass that was lost was converted into pure energy. E=MC2. The sun converts four million tons of tons of hydrogen into a few tons of helium each and every second. It has been doing this for five billion years and it will do so for five billion more years.

Answer 3

Nuclear fusion occurs *only* in the sun's core which is some 250,000 miles in diameter. In the core, about 4,700 metric tons of hydrogen are converted to helium every *second.*

Answer 4

For smaller stars, like our Sun, this chain of reactions is the important one:

http://en.wikipedia.org/wiki/Proton-proton_chain

Your science teacher's explanation is correct, though.