The radiation we receive from the Sun is caused by the energy released during nuclear reactions in the star. The Sun’s main nuclear fuel is hydrogen nuclei (a proton), which are fused together to produce helium nuclei (two protons and two neutrons). In this activity, students will create a diagram that shows how hydrogen nuclei fuse together to produce helium nuclei and energy.
During the first stage in the process, two protons fuse together to form a proton and neutron pair, known as Hydrogen-2, or deuterium. This releases a neutrino and a positron. Another proton fuses to the deuterium nucleus, creating a double proton, neutron triplet, known as Helium-3, which also releases a positron. When one Helium-3 nucleus fuses with another Helium-3 nucleus, a Helium (He-4) nucleus is formed, releasing two protons. At each stage of this reaction, energy is released.
All the elements up to iron (Fe) are created during fusion reactions in stars. Elements heavier than iron are created in supernova explosions in a reaction called neutron capture reactions.
To challenge more advanced students, have them think about why neutrinos and positrons are released at each stage. For students who need support, cut up the completed example storyboard and have them put the pieces together in the correct order. Another idea is to have your students make different descriptive visualizations of different fusion reactions, such as the fusion of helium nuclei to make carbon nuclei.
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Student Instructions
Create a storyboard to show how hydrogen nuclei are fused together to produce helium nuclei and energy. This is a very important nuclear reaction that happens inside stars like the Sun.
Engage students by simulating hydrogen fusion using simple classroom materials. Hands-on experiences help learners visualize how protons combine to form helium and release energy.
Collect items like colored balls, paper circles, or building blocks to stand in for protons, neutrons, and electrons. Visual props make abstract nuclear processes tangible for students.
Organize students into small groups, giving each member a particle card (proton, neutron, positron, neutrino, or photon). Role-playing brings the fusion steps to life and encourages participation.
Guide students as they physically combine and rearrange their props to mimic fusion reactions—merging protons, creating deuterium, forming helium-3, and producing helium-4. Pause after each step to identify what is released (energy, positrons, neutrinos).
Facilitate a conversation about what students observed, focusing on how energy and new elements are created in stars. Connecting the simulation to real astrophysics deepens understanding and retention.
Hydrogen fusion is the process where hydrogen nuclei (protons) combine to form helium nuclei inside stars, like the Sun. This reaction releases large amounts of energy, which powers stars and provides the light and heat essential for life on Earth.
Students can create a storyboard diagram showing each stage of hydrogen nuclei fusing into helium. Use shapes for particles, arrows for reactions, and include a key to explain symbols. Highlight the release of energy, neutrinos, and positrons at each step.
The main steps are: 1) Two protons fuse to form deuterium, releasing a neutrino and positron; 2) Deuterium fuses with another proton to make helium-3, releasing a positron; 3) Two helium-3 nuclei combine to form helium-4, releasing two protons. Energy is released at each stage.
Neutrinos and positrons are byproducts of the nuclear fusion process. Their release helps conserve energy, charge, and other quantities in reactions, and they provide evidence fusion is happening inside stars.
Fusion in stars creates elements up to iron (Fe) by combining lighter nuclei. In contrast, neutron capture reactions in supernovae make elements heavier than iron, using a burst of neutrons when massive stars explode.