The Sun Section 2

Section 2: Solar Activity

Preview

• Objectives

• Sunspots

• The Sunspot Cycle

• Solar Ejections

• Auroras

• Maps in Action

The Sun Section 2

Objectives

• Explain how sunspots are related to powerful magnetic fields on the sun.

• Compare prominences, solar flares, and coronal mass ejections.

• Describe how the solar wind can cause auroras on Earth.

The Sun Section 2

Sunspots

• Sunspot *

• The movements of gases within the sun’s convective zone and the movements caused by the sun’s rotation produce magnetic fields.

• These magnetic fields cause *.

The Sun Section 2

Sunspots

• Slower convection causes a decrease in the amount of gas that is transferring energy from the core of the sun to these regions of the photosphere.

• Because less energy is being transferred, these regions of the photosphere are considerably cooler than surrounding regions, and form areas of the sun that appear darker than their surrounding regions.

• * are called sunspots.

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The Sunspot Cycle

• Observations of sunspots have shown that the sun rotates.

• The numbers and positions of sunspots vary in a cycle that lasts about 11 years.

• Sunspots initially appear in groups about midway between the sun’s equator and poles. The number of sunspots increases over the next few until it reaches a peak of 100 of more sunspots.

• After the peak, the number of sunspots begins to decrease until it reaches a minimum.

The Sun Section 2

Sunspots

The Sun Section 2

Solar Ejections

• Other solar activities are affected by the sunspot cycle, such as the solar-activity cycle.

• The solar-activity cycle is caused *.

• This cycle is characterized *.

• Solar ejections are events in which the sun emits atomic particles.

The Sun Section 2

Solar Ejections, continued

Prominences

• prominence *

• Solar ejections include prominences, solar flares, and coronal mass ejections.

• Prominences are huge arches of glowing gases that follow the curved lines of the magnetic force from a region of one magnetic force to a region of the opposite magnetic polarity.

The Sun Section 2

Solar Ejections, continued

Solar Flares

• solar flare *

• Solar flares are the most violent of all solar disturbances.

• Solar flares release the energy stored in the strong magnetic fields of sunspots. This release can lead to the formation of coronal loops.

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Solar Ejections, continued

Coronal Mass Ejections

• coronal mass ejection *

• Some of the particles from a solar flare escape into space, increasing the strength of the solar wind.

• Particles also escape as coronal mass ejections. The particles in the ejection can cause disturbances to Earth’s magnetic field.

• These disturbances have been known to interfere with radio communications, satellites, and even cause blackouts.

The Sun Section 2

Auroras

• aurora *

• Auroras are the result of the interaction between the solar wind and Earth’s magnetosphere.

• Auroras are usually seen close to Earth’s magnetic poles because electrically charged particles are guided toward earth’s magnetic poles by Earth’s magnetosphere.

The Sun Section 2

Maps in Action

SXT Composite Image of the Sun