The Outer Layers of the Sun

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The large magnetic fields in sunspots decrease the flow of heat via convection causing the sunspot to become cool.

Sunspots are low temperature regions in the photosphere

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Sunspot cycle

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Sunspots can be used to measure the rotation of the Sun

Near the equator the Sun rotates once in 25 days.

The poles rotate more slowly, about once every 36 days.

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Sunspot cycle

Each 11 years, the Sun’s magnetic field changes direction. Overall cycle is 22 years.

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Granulation

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What direct observational evidence supports the model of thermonuclear reactions in the Sun’s core?

Neutrinos

Gamma rays

Sun spot counts

WMD inspections

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Solar magnetic fields also create other phenomena

Prominences

Flares

Solar wind

Coronal mass ejections

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Particles spiral around magnetic field lines

Magnetic field

Motion of charged particle (electron, proton, nucleus)

Particles, that we see, get trapped along magnetic field lines, that we don’t see, stretching out from the Sun.

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Prominences Cooler than photosphere.

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Solar flares Hotter, up to 40,000,000 K More energetic

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Coronal mass ejections eruption of gas, can reach Earth and affect aurora, satellites

Movie

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Coronal mass ejection

Movie

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Which statement is not correct?

The solar coronal temperature is about 106 K.

Sunspots are very cool and dark, with temperatures of about 300 K.

The Sun’s core has a temperature about 107 K.

The chromosphere is hotter than the photosphere.

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Guiding Questions