What is solar activity?

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What is solar activity?
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Solar activity is like weather

• Sunspots
• Solar Flares
• Solar Prominences
• All related to magnetic fields

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Sunspots Are cooler than other parts of the
Suns surface (4000 K) Are regions with strong
magnetic fields
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Charged particles spiral along magnetic field
lines.
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Magnetic fields store energy. Fields can change
their configuration and release that energy.
When they do, solar flares erupt, sending
bursts of X-rays and charged particles into space.
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Corona appears bright in X-ray photos in places
where magnetic fields trap hot gas
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How does solar activity affect humans?
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Coronal mass ejections send bursts of energetic
charged particles out through the solar system
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Charged particles streaming from Sun can disrupt
electrical power grid and can disable
communications satellites
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Energetic particles high in Earths atmosphere
cause auroras (Northern Lights aurora borealis
and Southern Lights aurora australis)
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How does solar activity vary with time?
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Sunspot cycle caused by the winding and twisting
of Suns magnetic field, but the details are not
well understood
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What have we learned?

• What causes solar activity?
• Convection combined with the rotation pattern of
  the Sunfaster at the equator than at the
  polescauses solar activity because these gas
  motions stretch and twist the Suns magnetic
  field.

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What have we learned?

• How does solar activity affect humans?
• Bursts of charged particles ejected from the Sun
  during periods of high solar activity can hamper
  radio communications,disrupt electrical power
  generation,and damage orbiting satellites.

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What have we learned?

• How does solar activity vary with time?
• The sunspot cycle, or the variation in the number
  of sunspots on the Suns surface,has an average
  period of 11 years.The magnetic field flip-flops
  every 11 years or so, resulting in a 22-year
  magnetic cycle.

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In-class activity

• Activity 27 Sunspots (pages 99-102)
• Do all parts of questions 1-5. Then well answer
  some clicker questions on them.

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5D. It is rare to find a sunspot above or below a
latitude of

1. 5 degrees north or south
2. 5 degrees north / 45 degrees south
3. 45 degrees north / 5 degrees south
4. 45 degrees north or south
5. None of the above

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Why do sunspots appear dark in pictures of the
Sun?

1. They are holes in the solar surface which let us
   see deeper, darker layers of the Sun.
2. They are thick clouds of cool gas which block the
   light from underneath.
3. They are too cold to emit any visible light.
4. None of the above.

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What powers the sun?

1. The fission of hydrogen into helium, which
   converts some mass into energy
2. The fission of helium into hydrogen, which
   converts some mass into energy
3. The complete conversion of the mass of some
   hydrogen into energy
4. The fusion of hydrogen into helium, which
   converts some mass into energy