How does the Sun make energy?
Advanced Level Guiding Question
Big Idea 3.2Educator Background
The Sun makes energy through the fusion of hydrogen into helium at the Sun's core. Fusion creates a huge amount of energy, so much energy that we cannot successfully duplicate it on Earth for a sustained period of time. The energy travels through the radiative zone and the convective zones of the Sun, through other layers, all the way to the Sun's surface (photosphere), outward into space, eventually reaching Earth. The Sun will continue to make energy for another 5 billion years, when it will run out of hydrogen atoms to fuse.
Learning Constraints
Students at this level are studying nuclear processes (HS-PS1-8), the processes that occur in the core of the Sun (HS-ESS1), and are able to quantify the law of conservation of energy (HS-PS3,4).
Connect to Heliophysics
Connection to the Sun is explicit in the NGSS. Emphasize to students that the Sun will continue to burn hydrogen at its core for billions of more years, as the forces in the Sun are balanced: the internal pressure created by nuclear fusion pushing outward and the external pressure of gravity pushing in on the star are in equilibrium. But when the amount of hydrogen becomes insufficient for nuclear fusion to create energy, there will no longer be enough internal pressure keeping the star from collapsing in on itself. Gravity takes over, compressing the core of the star, which then heats the interior of the star, causing it to expand. The Sun will expand into what is known as a red giant, most likely engulfing all of the inner planets, that would result, eventually, in the end of the solar system. As the red giant cools, the core of the star is left as a dim, cool object known as a white dwarf, which does not have enough energy to warm planets in orbit, if there were any.
Extend Exploration
Expand student exploration by having them investigate the fusion that occurs in more massive stars. Many layers of fusion create more elements, up to iron, as iron requires more energy to fuse than it creates. When the core of the star reaches this critical iron-rich state, the core catastrophically collapses, resulting in a supernova explosion. Heavier elements than iron are created in these explosions, and are sent flying out into the universe in all directions, creating opportunities for the creation of new stars and planetary systems.
Differentiate for Beginner Learners
Support beginner students by reviewing how energy is transferred (MS-PS3-3).
Differentiate for More Advanced Learners
Challenge students at the next level by having them investigate the Hertzspurng-Russell diagram and the different types of stars found in the universe.
Featured Advanced Resources
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Heliophysics Resource Database
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