3.4 Midweek summary
You have met the most famous equation in the world and what it means in practice. You have also learned about the physical process of nuclear fusion that powers the Sun.
you have also looked at precisely how stars release their energy – in the process converting their constituent gas from one chemical element (hydrogen) to another (helium). As you shall learn later, larger and older stars at later stages of their lifetimes may have additional types of fusion reactions taking place, but this process of conversion from hydrogen to helium is the principal reaction powering most stars in the stable part of their lifetimes.
In the next section you will consider where in the stellar hierarchy the Sun fits and how it compares with other stars in terms of size, temperature and energy output.