Chapter 14 Our Sun PDF

Our Sun Copyright © 2024 Pearson Education, Inc. All Rights Reserved 14.1 A Closer Look at the Sun Our goals for learning: – Why does the Sun shine? – What is the Sun's structure? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Why Does the Su...

Our Sun Copyright © 2024 Pearson Education, Inc. All Rights Reserved 14.1 A Closer Look at the Sun Our goals for learning: – Why does the Sun shine? – What is the Sun's structure? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Why Does the Sun Shine? Copyright © 2024 Pearson Education, Inc. All Rights Reserved A Closer Look at the Sun Is it on Fire? Copyright © 2024 Pearson Education, Inc. All Rights Reserved A Closer Look at the Sun Is it on Fire? Chemical energy content  10 000 years Luminosity Copyright © 2024 Pearson Education, Inc. All Rights Reserved A Closer Look at the Sun Is it on Fire? … No! Chemical energy content  10 000 years Luminosity Copyright © 2024 Pearson Education, Inc. All Rights Reserved A Closer Look at the Sun Is it Contracting? Copyright © 2024 Pearson Education, Inc. All Rights Reserved A Closer Look at the Sun Gravitational potential Is it Contracting?  25 million years Luminosity Copyright © 2024 Pearson Education, Inc. All Rights Reserved A Closer Look at the Sun Gravitational potential Is it Contracting? … No!  25 million years Luminosity Copyright © 2024 Pearson Education, Inc. All Rights Reserved A Closer Look at the Sun It can be powered by Nuclear energy! (E = mc 2 ) Nuclear potential energy (core)  10 billion years Luminosity Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Stable Sun (1 of 4) The Sun is in gravitational equilibrium (also called hydrostatic equilibrium). Weight of upper layers compresses lower layers. Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Stable Sun (2 of 4) Gravitational equilibrium: Energy supplied by fusion maintains the pressure that balances the inward crush of gravity. Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Stable Sun (3 of 4) Energy Balance: The rate at which energy radiates from the surface of the Sun must be the same as the rate at which it is released by fusion in the core. Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Stable Sun (4 of 4) Gravitational contraction: Provided the energy that heated the core as Sun was forming. Contraction stopped when fusion began. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Basic Properties of the Sun Radius: 6.9  108 m (109 times Earth ) Mass: 2  1030 kg ( 300,000 Earths ) Luminosity: 3.8  1026 watts Rotation: 25 days at the equator to 30 days at the poles Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Is the Sun’s Structure? Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Sun’s Structure (1 of 7) Solar wind: A flow of charged particles from the surface of the Sun Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Sun’s Structure (2 of 7) Corona: Very thin material Outermost layer of solar atmosphere  1 million K Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Sun’s Structure (3 of 7) Chromosphere: Middle layer of solar atmosphere  10,000 − 100,000 K Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Sun’s Structure (4 of 7) Photosphere: Where the plasma becomes transparent Visible surface of Sun  6000 Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Sun’s Structure (5 of 7) Convection Zone: Energy transported upward by rising hot gas Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Sun’s Structure (6 of 7) Radiation Zone: Energy transported upward by photons Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Sun’s Structure (7 of 7) Core: Energy generated by nuclear fusion at  15 million K Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Have We Learned? (1 of 5) Why does the Sun shine? – Chemical and gravitational energy sources could not explain how the Sun could sustain its luminosity for more than about 25 million years. – The Sun shines because gravitational equilibrium keeps its core hot and dense enough to release energy through nuclear fusion. Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Have We Learned? (2 of 5) What is the Sun's structure? – From inside out, the layers are: ▪ Core ▪ Radiation zone ▪ Convection zone ▪ Photosphere ▪ Chromosphere ▪ Corona Copyright © 2024 Pearson Education, Inc. All Rights Reserved 14.2 Nuclear Fusion in the Sun Our goals for learning: – How does nuclear fusion occur in the Sun? – How does the energy from fusion get out of the Sun? – How do we know what is happening inside the Sun? Copyright © 2024 Pearson Education, Inc. All Rights Reserved How Does Nuclear Fusion Occur in the Sun? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nuclear Fusion in the Sun (1 of 5) Fission Fusion Big nucleus splits into Small nuclei stick together smaller pieces. to make a bigger one. (Example: nuclear power (Example: the Sun, stars) plants) Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nuclear Fusion in the Sun (2 of 5) High temperatures and densities enable nuclear fusion to happen in the core. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nuclear Fusion in the Sun (3 of 5) The Sun releases energy by fusing four hydrogen nuclei into one helium nucleus. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Why Does the Sun Shine? (1 of 2) a. It is on fire b. Chemical energy c. Gravitational energy d. Nuclear fusion e. Nuclear fission Copyright © 2024 Pearson Education, Inc. All Rights Reserved Why Does the Sun Shine? (2 of 2) a. It is on fire b. Chemical energy c. Gravitational energy d. Nuclear fusion e. Nuclear fission Copyright © 2024 Pearson Education, Inc. All Rights Reserved Why Is the Sun Very Dense on the Inside? (1 of 2) a. Denser materials sank to its center. b. Weight of the outer layers keeps the density high. c. It formed from dense material. d. The photon pressure at the center is very high, increasing the overall density. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Why Is the Sun Very Dense on the Inside? (2 of 2) a. Denser materials sank to its center. b. Weight of the outer layers keeps the density high. c. It formed from dense material. d. The photon pressure at the center is very high, increasing the overall density. Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Is a Hydrogen Nucleus—the Particle That Fuses Into Helium in the Sun? (1 of 2) a. A neutron b. A proton c. An electron d. A positron Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Is a Hydrogen Nucleus—the Particle That Fuses Into Helium in the Sun? (2 of 2) a. A neutron b. A proton c. An electron d. A positron Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nuclear Fusion in the Sun (4 of 5) The proton–proton chain is how hydrogen fuses into helium in the Sun. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nuclear Fusion in the Sun (5 of 5) In 4 protons Out 4 He nucleus 2 gamma rays 2 positrons 2 neutrinos Total mass is 0.7% lower. This difference in mass is converted to energy by E=mc2 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nuclear Fusion in the Sun 4 1H → 1 4He + stuff with very little mass Mass of Proton - 1.6726 x 10-27 kg Mass of Helium nucleus - 6.643 x 10-27 kg How much energy is released when four protons is converted into one Helium nucleus? (Hint use. E=mc 2: ) (Hint2: Joule = 1 kg x m2/s2) A – 4 x 10-12 J B – 8 x 10-16 J C – 2 x 10-24 J D – 1 x 10-8 J Copyright © 2024 Pearson Education, Inc. All Rights Reserved Nuclear Fusion in the Sun 4 1H → 1 4He + stuff with very little mass Mass of Proton - 1.6726 x 10-27 kg Mass of Helium nucleus - 6.643 x 10-27 kg How much energy is released when four protons is converted into one Helium nucleus? (Hint use. E=mc 2: ) (Hint2: Joule = 1 kg x m2/s2) A – 4 x 10-12 J B – 8 x 10-16 J C – 2 x 10-24 J D – 1 x 10-8 J Copyright © 2024 Pearson Education, Inc. All Rights Reserved  Nuclear Fusion in the Sun 4 1H → 1 4He + stuff with very little mass Mass of Proton - 1.6726 x 10-27 kg Mass of Helium nucleus - 6.643 x 10-27 kg How much energy is released when four protons is converted into one Helium nucleus? (Hint use. E=mc 2 ) (Hint 2: Joule = 1 kg x 1 m2/s2) E = mc2 E = (4 x proton mass – Helium mass) x c2 E = (4 x 1.6726 x 10-27 kg – 6.643 x 10-27 kg) x (3 x 108 m/s)2 E ~ 4 x 10-12 J Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Thermostat Decline in core temperature causes fusion rate to drop, so core contracts and heats up. Rise in core temperature causes fusion rate to rise, so core expands and cools down. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Thought Question What would happen inside the Sun if a slight rise in core temperature led to a rapid rise in fusion energy? A. The core would expand and heat up. B. The core would expand and cool. C. The Sun would blow up like a hydrogen bomb. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Thought Question What would happen inside the Sun if a slight rise in core temperature led to a rapid rise in fusion energy? A. The core would expand and heat up. Thecor ectan B. The core would expand and cool. sweri s C. The Sun would blow up like a hydrogen bomb. The solar thermostat keeps burning rate steady. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Handout Activity Let’s work on Activity Manual Pg. 21 - 22. Fusion in the Sun: The proton-proton chain Copyright © 2024 Pearson Education, Inc. All Rights Reserved Clickers: Fusion Pathways (5 questions) Scoring: 5 points for the correct answer 1 point for the wrong answer It’s worth guessing even if you have no idea Copyright © 2024 Pearson Education, Inc. All Rights Reserved How many neutrinos are produced along with every 4He++ nucleus in pathway A? A-0 B-1 C-2 D-4 E - 10 Copyright © 2024 Pearson Education, Inc. All Rights Reserved How many neutrinos are produced along with every 4He++ nucleus in pathway B? A-0 B-1 C-2 D-4 E - 10 Copyright © 2024 Pearson Education, Inc. All Rights Reserved How many neutrinos are produced along with every 4He++ nucleus in pathway C? A-0 B-1 C-2 D-4 E - 10 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Which of the pathways is the most common? A-A B-B C-C Copyright © 2024 Pearson Education, Inc. All Rights Reserved How many times more nuclei will it produce than the others? A-2 B-4 C-8 D - 12 E - 50 Copyright © 2024 Pearson Education, Inc. All Rights Reserved Energy Escape from the Sun (1 of 4) Copyright © 2024 Pearson Education, Inc. All Rights Reserved Energy Escape from the Sun (2 of 4) Energy gradually leaks out of the radiation zone in the form of randomly bouncing photons. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Energy Escape from the Sun (3 of 4) Convection (rising hot gas) takes energy to surface. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Energy Escape from the Sun (4 of 4) Bright blobs on photosphere show where hot gas is reaching the surface. Copyright © 2024 Pearson Education, Inc. All Rights Reserved How We Know What Is Happening Inside the Sun? Copyright © 2024 Pearson Education, Inc. All Rights Reserved We Learn About the Inside of the Sun by … making mathematical models observing solar vibrations observing solar neutrinos Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Vibrations Patterns of vibration on the surface tell us about what the Sun is like inside. Here, vibrations revealed by Doppler shifts are shown. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Models Data on solar vibrations agree very well with mathematical models of solar interior. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Neutrinos (1 of 2) Neutrinos created during fusion fly directly through the Sun. Observations of these solar neutrinos can tell us what's happening in the core. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Neutrinos (2 of 2) Solar neutrino problem: Early searches for solar neutrinos failed to find the predicted number. More recent observations find the right number of neutrinos, but some have changed form. Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Have We Learned? (3 of 5) How does nuclear fusion occur in the Sun? – The core's extreme temperature and density are just right for nuclear fusion of hydrogen to helium through the proton–proton chain. – Gravitational equilibrium acts as a thermostat to regulate the core temperature because fusion rate is very sensitive to temperature. Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Have We Learned? (4 of 5) How does the energy from fusion get out of the Sun? – Randomly bouncing photons carry energy through the radiation zone. – Rising of hot plasma carries energy through the convection zone to photosphere. How do we know what is happening inside the Sun? – Mathematical models agree with observations of solar vibrations and solar neutrinos. Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Causes Solar Activity? (1 of 2) Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity Is Like “Weatherˮ Sunspots Solar flares Solar prominences All these phenomena are related to magnetic fields. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (1 of 10) Sunspots Are cooler than other parts of the Sun's surface (4000 K ) elvin Are regions with strong magnetic fields Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (2 of 10) Zeeman Effect We can measure magnetic fields in sunspots by observing the splitting of spectral lines. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (3 of 10) Charged particles spiral along magnetic field lines. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (4 of 10) Loops of bright gas often connect sunspot pairs. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (5 of 10) Magnetic activity causes solar flares that send bursts of x-rays and charged particles into space. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (6 of 10) Magnetic activity also causes solar prominences that erupt high above the Sun's surface. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (8 of 10) Coronal mass ejections send bursts of energetic charged particles out through the solar system. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Effects of Solar Activity on Earth https://www.youtube.com/watch?v=TWjtYSRlOUI&t=109s Copyright © 2024 Pearson Education, Inc. All Rights Reserved Effects of Solar Activity on Earth Charged particles streaming from the Sun can disrupt electrical power grids and can disable communications satellites. Copyright © 2024 Pearson Education, Inc. All Rights Reserved How Does Solar Activity Vary with Time? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (9 of 10) There are additional variances over longer periods. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Solar Activity (10 of 10) The sunspot cycle has something to do with winding and twisting of the Sun's magnetic field. Copyright © 2024 Pearson Education, Inc. All Rights Reserved The Sunspot Cycle and Earth’s Climate Despite an 11-year cycle, the amount of sunlight has remained approximately constant while Earth has warmed. Copyright © 2024 Pearson Education, Inc. All Rights Reserved What Have We Learned? (5 of 5) What causes solar activity? – Stretching and twisting of magnetic field lines near the Sun's surface cause solar activity. How does solar activity vary with time? – Activity rises and falls with an 11-year period. Copyright © 2024 Pearson Education, Inc. All Rights Reserved Handout Activity How is a star like a balloon? Copyright © 2024 Pearson Education, Inc. All Rights Reserved Clickers: Star/balloon (5 questions) Scoring: 5 points for the correct answer 1 point for the wrong answer It’s worth guessing even if you have no idea Copyright © 2024 Pearson Education, Inc. All Rights Reserved What keeps the particles in a star from flying away from each other? A - Nuclear fusion B - Nuclear fission C - The electrostatic force D - Gravity E - The rubber surface Copyright © 2024 Pearson Education, Inc. All Rights Reserved What stops a star from collapsing A - The force of gravity B - Pressure from heat in the core C - Pressure from radiation (photons) in the core D - Pressure from heat and radiation (photons) in the core E - The force of gravity and pressure from heat in the core Copyright © 2024 Pearson Education, Inc. All Rights Reserved If the rate of hydrogen fusion in a star would somehow increase, what do you think would happen to the star? A - It would expand B - It would contract C - It would explode D - It would do nothing E - It would get heavier Copyright © 2024 Pearson Education, Inc. All Rights Reserved For a star to be in equilibrium, there must be a balance between the rate that ____ is generated in the star and the rate at which it is lost, it’s _____ A - fusion, temperature B - gravity, luminosity C - luminosity, temperature D - luminosity, gravity E - energy, luminosity Copyright © 2024 Pearson Education, Inc. All Rights Reserved 14.3 The Sun–Earth Connection Our goals for learning: – What causes solar activity? – How does solar activity vary with time? Copyright © 2024 Pearson Education, Inc. All Rights Reserved