Chapter 29.2 Solar Activity

1. Chapter 29.2 Solar Activity 1e- Students know the sun is a typical star and is powered by nuclear reactions, primarily the fusion of hydrogen to form helium Objective 1: Explain how sunspots are related to powerful magnetic fields on the sun Objective 2: Compare prominences, solar flares, and coronal mass ejections Objective 3: Describe how the solar wind can cause auroras on Earth

2. Solar Activity • The gases that make up the sun’s interior and atmosphere are in constant motion • Locations on the sun rotate at different speeds because it’s a ball of gases

3. Sunspots Sunspot Granulation • Sunspots – a dark area of the photosphere of the sun that is cooler than the surrounding areas and that has a strong magnetic field • The photosphere has a grainy appearance called granulation. • Granulation is most visible around sunspots • Large sunspots are bigger than the Earth

4. Sun’s magnetic field causes convection to slow in parts of the convection zone • Gases move faster at equator • The field lines twist/break causing sunspots • Slow convection = decrease in amount of gas that is transferring energy from core to photosphere • Sunspots occur in pairs

5. The Sunspot Cycle • The numbers and positions of sunspots vary in a cycle that lasts about 11 years • The cycle begins when the number of sunspots increase • They start in small numbers and slowly move towards the poles • They peak at about 100 sunspots and then start to slowly disappear

6. Objective 1: Explain how sunspots are related to powerful magnetic fields on the sun • What causes a decrease in the amount of energy being transferred from the core to the photosphere? • Slow convection • What causes the convection to slow down in the convection zone? • The Sun’s magnetic field • What is the fewest number of sunspots that can be present at one time? • 2 • How long is a sunspot cycle? • 11 years

7. Solar Ejections • Solar activities are affected by the sunspot cycle. The solar-activity cycle is caused be the changing solar magnetic field • Solar ejections are events when sun emits solar ejections • Prominences • Solar Flares • Coronal Mass Ejections

8. Prominences • Prominence – a loop of relatively cool incandescent gas that extends above the photosphere • Gas comes from the Chromosphere

9. Solar Flare • Solar Flare – an explosive release of energy that comes from the sun and that is associated with magnetic disturbances on the sun’s surface • The most violent solar activity • The exact cause is unknown. • Temp = 20,000,000 ⁰C

10. Coronal Mass Ejections (CME) • CME - part of coronal gas that is thrown into space from the sun • geomagnetic storms – a sudden disturbance in Earth’s magnetic field • Can interfere w/radio communication on Earth, damage satellites and cause blackouts

11. Objective 2: Compare prominences, solar flares, and coronal mass ejections • What is a loop of cool incandescent gas? • Prominence • What can coronal mass ejections cause on Earth? • Communication disruption, Satellite damage, and blackouts • What is the temperature of a solar flare? • 20,000,000 ⁰C • What is a disturbance in Earth’s magnetic field? • Geomagnetic storm

12. Auroras • Colored light produced by the charged particles from the solar wind and particles in Earth’s upper atmosphere • Visible after solar flares • Seen close to Earth’s magnetic poles • Northern lights or Aurora Borealis • Southern lights or Aurora Australis

13. Objective 3: Describe how the solar wind can cause auroras on Earth • What 2 things interact to produce auroras? • Solar winds and particles in the atmosphere • Where can Auroras be seen? • Near the poles • What is another name for Aurora borealis? • Northern lights • When are auroras more common? • After a solar flare