Nuclear Fission and Nuclear Fusion

Nuclear Fusion
Where does the sun get is energy from?
How is Hydrogen made into helium?
What forces have to be overcome?
Compare fission and fusion.

The sun is basically a giant ball of hydrogen plasma. Gravity causes the ball to contract to a high enough density to begin nuclear fusion. Two hydrogen atoms fuse to form one helium atom, and energy is released in the process. Heat energy expelled by plants and animals mostly goes into the surrounding environment. The sun affects us, but life on earth has basically zero effect on the sun.
The sun uses a series of nuclear reactions called the hydrogen cycle. First, two protons hit each other and one is converted into a neutron and a particle called a positron. The proton and neutron come together to make a nucleus. This is a standard nuclear reaction. 
Then, another proton hits the deuterium nucleus. Now that nucleus has two protons and one neutron. This is a helium-3 nucleus. Finally, two helium-3 nuclei hit each other. Two protons and two neutrons stick together to make a helium-4 nucleus. The other two protons fly away to enter into other reactions. The net result is that six protons come together to make a helium nucleau (which has two protons and two neutrons), two positrons, and two protons.
The first reaction in this sequence is very slow and is why the sun is still shining after 5 billion years. Other types of stars (red giants) use another sequence of nuclear reactions called the carbon cycle, but this doesn't happen in our sun.
Fission Versus Fusion
| Fission | Fusion |
Definition | Fission is the splitting of a larger atom into two or more smaller ones. | Fusion is the fusing of two or more lighter atoms into a larger one. |
Natural occurrence of the process | Fission reaction does not normally occur in nature. It is usually man influent | Fusion occurs in stars, such as the sun. |
By-products of the reaction | Fission produces many highly radioactive particles. | Few radioactive particles are...