HS-ESS1-1: Nuclear Fusion and the Sun's Energy

Develop a model based on evidence to illustrate the life span of the sun and the role of nuclear fusion in the sun’s core to release energy in the form of radiation. (Scale, Proportion, and Quantity)

 

Clarification Statement: Emphasis is on the energy transfer mechanisms that allow energy from nuclear fusion in the sun’s core to reach Earth. Examples of evidence for the model include observations of the masses and lifetimes of other stars, as well as the ways that the sun’s radiation varies due to sudden solar flares (“space weather”), the 11-year sunspot cycle, and non-cyclic variations over centuries.

 

Assessment Boundary: Assessment does not include details of the atomic and sub-atomic processes involved with the sun’s nuclear fusion.

Objectives
  1. Students will be able to explain how nuclear fusion produces energy in the sun.
  2. Students will understand the process of nuclear fusion and its role in the creation of elements in the universe.
  3. Students will be able to describe the layers of the sun's interior and the mechanisms by which energy is transported from the core to the outer layers.
  4. Students will understand how the sun's energy impacts Earth's climate, weather patterns, and ecosystems.
  5. Students will be able to identify and explain key vocabulary terms related to nuclear fusion and the sun's energy.
  6. Students will develop critical thinking skills by analyzing and comparing different models of the process of nuclear fusion and the sun's energy.
  7. Students will be able to apply their understanding of nuclear fusion and the sun's energy to explain phenomena such as solar flares, coronal mass ejections, and the solar wind.
  8. Students will understand the importance of the sun's energy to human societies and technologies, including solar power and space exploration.

Vocabulary
  1. Nuclear Fusion: The process by which two atomic nuclei combine to form a heavier nucleus, releasing energy in the process.
  2. Proton: A subatomic particle found in the nucleus of an atom that carries a positive charge.
  3. Neutron: A subatomic particle found in the nucleus of an atom that carries no charge.
  4. Hydrogen: The simplest and most abundant element in the universe, with one proton and one electron.
  5. Helium: A gas that is formed by the fusion of hydrogen atoms in the sun's core, with two protons and two neutrons.
  6. Radiative Zone: The region of the sun's interior where energy is transported from the core to the outer layers via photons.
  7. Convective Zone: The outermost layer of the sun's interior where energy is transported by the movement of gas molecules.
  8. Photosphere: The visible surface of the sun, where most of the sun's light and heat is emitted.
  9. Solar Flare: A sudden burst of energy that occurs on the sun's surface, releasing large amounts of radiation and particles into space.
  10. Solar Wind: A stream of charged particles that are constantly flowing outward from the sun, shaping the magnetic fields of the solar system.

Teacher Notes
  1. Prior knowledge: Before beginning the lesson, assess students' prior knowledge of the sun and its energy. This can include asking open-ended questions, conducting a pre-assessment quiz, or having students brainstorm what they know about the sun.
  2. Engage students: Start the lesson with a hook to engage students and get them interested in the topic. This could include showing images or videos of the sun, asking thought-provoking questions, or conducting a group discussion.
  3. Visual aids: Use visual aids such as diagrams, models, and videos to help students visualize the processes involved in nuclear fusion and the sun's energy. This can also help to accommodate different learning styles and keep students engaged.
  4. Hands-on activities: Incorporate hands-on activities, such as a simulation of the sun's interior or a solar panel building project, to help students understand the practical applications of the concepts being taught.
  5. Differentiated instruction: Differentiate instruction by providing students with various resources and opportunities to learn, such as articles, readings, videos, or podcasts. This can help accommodate different learning styles and abilities.
  6. Summative assessment: At the end of the lesson, conduct a summative assessment to evaluate students' understanding of the material. This can include quizzes, essays, presentations, or other assessments that align with the lesson objectives.
  7. Follow-up: Follow up with students after the lesson to provide feedback on their performance, answer any questions they may have, and provide resources for further learning.
Evidence Statemet HS ESS 1 1

Solar Flares

Starry sky and moving stars

Nuclear fusion is the source of Sun's phenomenal energy output. The Hydrogen and Helium atoms that constitute Sun, combine in a heavy amount every second to generate a stable and a nearly inexhaustible source of energy.

 

Sun – The Ultimate Nuclear Fusion Reactor

 

Every second, the Sun fuses 620 billion Kg of Hydrogen nuclei (protons) into Helium, to produce 384.6 trillion trillion Joules of energy per second. This is equivalent to the energy released in the explosion of 91.92 billion megatons of TNT per second.

Sun is our star and the source of all energy on Earth. Solar energy sustains all the life on our planet through photosynthesis, and sets the rhythm of our climate and seasons. Since ages, people have pondered about the source of Sun’s extraordinarily high energy output which amounts to 3.846 × 1026 Joules of energy, per second. What endows stars like our Sun with this almost endless energy? Today, thanks to years of painstaking research, we know the answer. Nuclear fusion (the fusing together of atomic nuclei into heavier nuclei at high temperatures) is the key which unlocks almost limitless power for the Sun.

Sun - The Ultimate Nuclear Fusion Reactor
  • The Sun is our star and the source of all energy on Earth.
  • Every second, the Sun fuses 620 billion kilograms of hydrogen nuclei into helium, producing 384.6 trillion trillion joules of energy per second.
  • This enormous energy output is equivalent to the explosion of 91.92 billion megatons of TNT per second.
  • Nuclear fusion, which involves the fusing of atomic nuclei into heavier nuclei at high temperatures, is the process that powers the Sun.
  • In the Sun's core, the primary fusion reaction is the proton-proton chain, which fuses hydrogen nuclei to form helium.
  • The energy released by nuclear fusion in the Sun sustains all life on Earth through photosynthesis and drives the Earth's climate and weather patterns.
  • Scientists are working to harness the power of nuclear fusion for use here on Earth, which could provide clean and almost limitless energy. However, it remains a challenging task due to the extreme temperatures and pressures required for fusion to occur.

Atomic Weight

Atomic weight is the total number of protons and neutrons in the nucleus, while atomic number is the number of protons or electrons that make the atom. Hydrogen is denoted as 11H, where the number in the superscript is the atomic weight and the number in subscript is the atomic number. Since the thermonuclear reactions occur at the level of a million Kelvins, all atoms are stripped of their electrons in the solar core.

What is Nuclear Fusion?

Sun is a star and all stars are big balls of gas, primarily made up of gargantuan amounts of Hydrogen and Helium. About 75% of the Sun is made up of Hydrogen, while the rest is mostly all Helium.

What Makes Sun, Stable?

Solar interior witnesses a constant tussle between the crushing gravitational force and thermal pressure, generated by nuclear fusion in the core. The Sun is stable due to the hydrostatic equilibrium achieved between the self-gravity of the Sun and the thermal pressure generated by fusion in the core.

 

Where Does Nuclear Fusion Occur in the Sun
  1. Nuclear fusion occurs in the core of the sun, which is the central region where the temperature and pressure are high enough to initiate and sustain the fusion process. The core of the sun has a temperature of around 15 million degrees Celsius and a pressure of about 250 billion times that of Earth's atmospheric pressure at sea level.
  2. In the core of the sun, hydrogen atoms are fused together to form helium through a process called the proton-proton chain. The energy produced by this fusion process is released in the form of light and heat, which radiate outwards from the core and provide the energy that sustains the sun's brightness and warmth.
  3. Surrounding the core is the radiative zone, where the energy released by fusion in the core is transferred through a process of radiation. Beyond the radiative zone is the convective zone, where energy is transported by the movement of hot gas bubbles called convection cells.
  4. Together, these layers form the structure of the sun and allow the energy produced by nuclear fusion in the core to be transported outwards to the surface of the sun and beyond.

Nuclear Fusion

The fusion process in the sun is known as nuclear fusion, which is the process of combining two atomic nuclei to form a heavier nucleus. The sun's primary source of energy is the fusion of hydrogen nuclei (protons) to form helium.

Here's how it happens:

  1. In the sun's core, temperatures are around 15 million degrees Celsius, and the pressure is intense. These extreme conditions allow the positively charged protons to overcome their natural repulsion and move close enough to fuse.

  2. The first step in the fusion process is the creation of a proton-proton chain. Two protons come together to form a deuterium nucleus (one proton and one neutron), releasing a positron (a positively charged particle) and a neutrino in the process.

  3. The deuterium nucleus then combines with another proton to form a helium-3 nucleus (two protons and one neutron), releasing a gamma ray in the process.

  4. Two helium-3 nuclei then combine to form a helium-4 nucleus (two protons and two neutrons), releasing two protons and a large amount of energy in the form of gamma rays.

This process of proton-proton fusion is the primary energy source for the sun and other similar stars. It is a delicate balance between the gravitational force pulling inward and the pressure generated by the fusion process pushing outward. The energy produced by this process is released as light and heat, which provides the energy that sustains life on Earth.

The Atomic Nucleus

 Everything is made up of atoms. They are the smallest indivisible units of any object. The central core of an atom is the nucleus, which is quite dense and packed with most of the atom’s mass, with electrons revolving around it.

 

What is Nucleus?

The nucleus consists of two types of particles – protons and neutrons. A proton has a unit positive electric charge (1.6 x 10-19 Coulomb), while the neutron is neutral. A type of an atom is decided by the number of protons in it.

There are 92 different types of naturally occurring atoms. Hydrogen is the simplest type of atom that you could think of. Its nucleus is just a proton.