The SunThe Sun

Unit 6: AstronomyUnit 6: Astronomy

First…we have to discuss light

First…we have to discuss light Information about universe

Light emitted from stars and other bodies in space

Electromagnetic spectrum = arrangement of waves according to their wavelengths and frequencies We see visible part of spectrum

Information about universe Light emitted from stars and other

bodies in space Electromagnetic spectrum =

arrangement of waves according to their wavelengths and frequencies We see visible part of spectrum

Visible LightVisible Light

A range of waves with various wavelengths

Passed through a prism Violet bent more

than blue Blue bent more

than green Etc.

A range of waves with various wavelengths

Passed through a prism Violet bent more

than blue Blue bent more

than green Etc.

SpectroscopySpectroscopy

Study of the properties of light that depend on wavelength

absorption spectrum = visible light is passed through a cool gas under low pressure

Study of the properties of light that depend on wavelength

absorption spectrum = visible light is passed through a cool gas under low pressure

Absorption SpectrumAbsorption Spectrum

Each element or compound in gaseous form produces unique set of spectral lines

Studying a star Lines indicate

which elements --> star’s chemical composition

Each element or compound in gaseous form produces unique set of spectral lines

Studying a star Lines indicate

which elements --> star’s chemical composition

Remember the Doppler Effect?

Remember the Doppler Effect?

Light from a source moving away from you appears redder Waves are lengthened

Moving toward you appears bluer Waves are shortened

Determine whether a star or other body in space is moving away from or toward Earth Measured from the dark

lines in spectra and comparing them with a standard spectrum

Light from a source moving away from you appears redder Waves are lengthened

Moving toward you appears bluer Waves are shortened

Determine whether a star or other body in space is moving away from or toward Earth Measured from the dark

lines in spectra and comparing them with a standard spectrum

Intro to the SunIntro to the Sun

“Average” star Earth’s primary

source of energy Only star whose

surface we can study Diameter = 109

Earths Mass = 332,000

times of Earth

“Average” star Earth’s primary

source of energy Only star whose

surface we can study Diameter = 109

Earths Mass = 332,000

times of Earth

Our Sun is a StarOur Sun is a Star

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Structure of the SunStructure of the Sun

Sun is made of gas No clear

boundaries between layers

4 parts Solar interior Photosphere Chromosphere corona

Sun is made of gas No clear

boundaries between layers

4 parts Solar interior Photosphere Chromosphere corona

PhotospherePhotosphere

Visible surface Radiates most of the

sunlight we see Layer of gas Grainy texture -->

granules Composition = 90%

hydrogen, almost 10% helium Dark lines of

absorption spectrum

Visible surface Radiates most of the

sunlight we see Layer of gas Grainy texture -->

granules Composition = 90%

hydrogen, almost 10% helium Dark lines of

absorption spectrum

ChromosphereChromosphere

Above the photosphere

Thin layer of hot gases

Can see during a total solar eclipse (red rim) Light from

photosphere is blocked out

Above the photosphere

Thin layer of hot gases

Can see during a total solar eclipse (red rim) Light from

photosphere is blocked out

CoronaCorona

Outermost portion of the solar atmosphere

Weak Envelope of gases

--> extend a million kilometers from sun

Outermost portion of the solar atmosphere

Weak Envelope of gases

--> extend a million kilometers from sun

CoronaCorona

Solar wind = streams of protons and electrons ejected at high speed from the corona Travel through solar

system and are lost to space

Alters appearance of bodies in the solar system

Earth’s magnetic field doesn’t allow them to reach our surface --> do affect our atmosphere

Solar wind = streams of protons and electrons ejected at high speed from the corona Travel through solar

system and are lost to space

Alters appearance of bodies in the solar system

Earth’s magnetic field doesn’t allow them to reach our surface --> do affect our atmosphere

Solar WindSolar Wind

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SunspotsSunspots Dark spots on the surface

of the sun Temperature is less than the

surrounding solar surface Number of sunspots

observable vary in an 11-year cycle Increases to maximum (100)

--> then decrease to minimum

Motion of sunspots --> sun rotates about once a month Not all parts rotate at the

same speed (gaseous)

Dark spots on the surface of the sun Temperature is less than the

surrounding solar surface Number of sunspots

observable vary in an 11-year cycle Increases to maximum (100)

--> then decrease to minimum

Motion of sunspots --> sun rotates about once a month Not all parts rotate at the

same speed (gaseous)

SunspotsSunspots

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The Solar CycleThe Solar Cycle

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ProminencesProminences

Concentration of gases often appearing as arches extending beyond corona Sometimes can

erupt matter escapes Sun’s atmosphere

Concentration of gases often appearing as arches extending beyond corona Sometimes can

erupt matter escapes Sun’s atmosphere

Solar FlaresSolar Flares Sudden eruption

Above sunspot cluster Release lots of energy

(UV, radio, X-ray) Atomic particles released

--> reach Earth day later (affect long-distance radio communications)

Auroras = bright display of light caused by solar radiation interacting with the upper atmosphere at the poles Following strong solar

flare

Sudden eruption Above sunspot cluster Release lots of energy

(UV, radio, X-ray) Atomic particles released

--> reach Earth day later (affect long-distance radio communications)

Auroras = bright display of light caused by solar radiation interacting with the upper atmosphere at the poles Following strong solar

flare

How Solar Activity Affects the Earth

How Solar Activity Affects the Earth

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Solar InteriorSolar Interior

Source of energy = nuclear fusion Combining of the nuclei of lighter

elements to form a heavier element Energy released because some

matter is converted to energy

Source of energy = nuclear fusion Combining of the nuclei of lighter

elements to form a heavier element Energy released because some

matter is converted to energy

Introduction to Nuclear Energy

Introduction to Nuclear Energy

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Process of nuclear fusionProcess of nuclear fusion

Converts four hydrogen nuclei into the nucleus of a helium atom Lots of energy released! 4 hydrogens = 4.032 amu; 1 helium

= 4.003 amu Missing mass! (.029 amu)

Animation

Converts four hydrogen nuclei into the nucleus of a helium atom Lots of energy released! 4 hydrogens = 4.032 amu; 1 helium

= 4.003 amu Missing mass! (.029 amu)

Animation

Process of nuclear fusionProcess of nuclear fusion

E = mc2

c = speed of light Speed of light is very high (300,000

km/sec) --> amount of energy released from small mass is very high One pinhead of hydrogen to helium >

burning thousands of tons of coal

E = mc2

c = speed of light Speed of light is very high (300,000

km/sec) --> amount of energy released from small mass is very high One pinhead of hydrogen to helium >

burning thousands of tons of coal

Nuclear Fusion in the SunNuclear Fusion in the Sun

Small percentage of hydrogen is converted to energy Helium forms the solar core --> grows

Small percentage of hydrogen is converted to energy Helium forms the solar core --> grows

Future of the SunFuture of the Sun

Will the sun run out of hydrogen fuel? Last another 100 billion years

Sun will grow Engulf Earth

Sun can exist in its stable state for 10 billion years Already 4.5 billion years old

Will the sun run out of hydrogen fuel? Last another 100 billion years

Sun will grow Engulf Earth

Sun can exist in its stable state for 10 billion years Already 4.5 billion years old