Outer Layers of the Sun’s Atmosphere

• Photosphere - the 5800 K layer we see

• Chromosphere - the red layer observed using a hydrogen filter at a million degrees

• Corona - the incredibly thin outer atmosphere at millions of degrees

The photosphere is the visible layer of the

SunGranulation caused by convection

Thermal Convection

movie

Granulation caused by convection

Sunspots are the most well

known feature on

the photosphere

Above the photosphere, the chromosphere is characterized by

spikes of gas called spicules

Supergranules surrounded by spicules

The corona ejects some of its mass into space as the solar wind

Solar Wind• Charged particles (mostly protons

and electrons) streaming outward from the sun at 450 km/sec

• Causes • comet’s tails• aurorae

Monitoring sunspots reveals the solar cycle and the Sun’s rotation

The daily movement of sunspots reveals that

the Sun’s rotation

takes about 4 weeks

The annual change in numbers of sunspots reveals that the Sun experiences an 11-year solar cycle

Maximum number

Minimum number

The cyclical change in the latitude of sunspots also reveals that the Sun experiences an 11-year solar cycle

The Sun’s magnetic fields create sunspots

Zeeman effect - spectral lines split in regions of high magnetic fields

Magnetic field lines connect sunspots on the Sun’s photosphere

Babcock’s magnetic dynamo is one possible explanation of the sunspot cycle where magnetic field lines become complexly entangled after many solar rotations

Solar magnetic fields also create other atmospheric phenomena

• plages• filaments

Solar magnetic fields also create other atmospheric phenomena

• plages• filaments• prominences

Solar magnetic fields also create other atmospheric phenomena

• plages• filaments• prominences• solar flares

Solar magnetic fields also create other atmospheric phenomena

• plages• filaments• prominences• solar flares• coronal holes

Solar magnetic fields also create other atmospheric phenomena

• plages• filaments• prominences• solar flares

• coronal holes• coronal mass

ejections (CMEs)

Thermonuclear reactions in the core of the Sun

produce its energy

At extremely high temperatures and pressures, 4 Hydrogen atoms can combine to make 1 Helium atom and release

energy in the process according to E = mc2

4H He + energy

HYDROGEN FUSION

Solar models

describe how

energy escapes from the

Sun’s core through

the:

• Core• Radiative zone• Convective Zone

Helioseismology is the study of solar vibrations in order to

determine the detailed interior structure of the Sun

Quiz 3

Review

1. The Doppler effect is the change in the wavelength of light caused by the source

A) being within a high gravitational field.

B) being embedded in a cloud of dust and gas.

C) being in an intense magnetic field.

D) moving with respect to the observer.

Quiz 3

Answer: D

Quiz 3

Answer:

2. 98% of the mass of the universe is in the form of

A) hydrogen and helium.

B) nitrogen and oxygen.

C) iron and silicon.

D) hydrogen.

A

Quiz 3

Answer:

3. The correct sequence of planets in our solar system, from the Sun outward, is

A) Mercury, Earth, Venus, Mars, Jupiter, Saturn, Uranus, Neptune.

B) Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

C) Mercury, Venus, Earth, Mars, Saturn, Uranus, Jupiter, Neptune.

D) Mercury, Venus, Mars, Earth, Jupiter, Saturn, Uranus, Neptune.

B

Quiz 3

Answer:

4. The San Andreas fault in California is an example of

A) a subduction zone, a region where two tectonic plates are pushing directly against oneanother.

B) a hot spot, where warm material rises due to convection in the Earth's mantle.

C) a spreading center, where two tectonic plates are being pushed away from each other.

D) a transform fault, where two tectonic plates are sliding past each other.

D

Quiz 3

Answer:

5. Most of the craters on the Moon were formed by

A) water erosion, followed by evaporation early in the Moon's history, leaving behind theempty basins, the maria, and craters.

B) a nuclear war in which the lunar inhabitants wiped themselves off the face of the Moon.

C) bombardment by objects of various sizes from space.

D) volcanic action, the craters being the old calderas of volcanoes.

C

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Answer:

6. What is the major constituent of the atmosphere of both Venus and Mars?

A) CO2 (carbon dioxide).

B) CH4 (methane or natural gas).

C) H2O (water vapor).

D) H2 (hydrogen).

A

Quiz 3

Answer:

7. Which of the following objects rotates the most quickly around its own axis?

A) Venus.

B) The Earth's Moon.

C) Earth.

D) Jupiter.

D

Quiz 3

Answer:

8. How did Comet Shoemaker-Levy 9 achieve lasting fame?

A) It became the first comet to be visited by spacecraft.

B) It crashed into Jupiter.

C) It exploded after passing too close to the Sun.

D) It just missed the Earth, passing between the Moon and the Earth.

B

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Answer:

9. Which satellite of Jupiter is volcanically active?

A) Europa

B) Io

C) Callisto

D) Ganymede

B

Quiz 3

Answer:

10. What is the composition of Saturn's rings?

A) Particles of methane and ammonia ice.

B) Sodium and sulfur ions.

C) Small grains of rock.

D) Water ice or ice-coated rock.

D