The Sun’s Structure & FeaturesChapter 26.1

Chapter 26.1

70% H

28% He

The sun is made up of gasTemps: 15 million K at core / 5000 K at surfaceThe sun gives off energy in all wavelengths of the ELECTROMAGNETIC SPECTRUM (Visible light, Infrared, X ray, gamma rays, etc)

Sun’s Energy: Nuclear Fusion

When the star’s core gets hot enough (millions of degrees) Nuclear Fusion starts.

Hydrogen + Hydrogen Helium + ENERGY (+ neutron)

Fusion continues to make heavier & heavier elements. Stops at Iron

Nuclear Fusion

Nuclear Fusion is the process that releases energy on stars. It takes place in the core of the star.

It starts when gravity pulls nebula together and temperatures increase to millions of degrees.

In nuclear fusion, the nuclei (protons and neutrons) of atoms fuse together to make heavier elements and release energy.

H + H Helium + (neutron) + ENERGY

•Fusion continues to produce heavier elements and release energy until IRON is made.

•Fusion stops with IRON.

•Elements heavier than Iron can only be made during the supernova explosion.

•The star will collapse or explode.

What keeps the sun stable?For a star to remain stable the force of GRAVITY

must be balanced by the force of PRESSURE.• Gravity – pulls sun inward (collapsing• Thermal Pressure – pushes outward (keeping

the sun from collapsing)– Cause of Pressure is heat from fusion

•When the sun runs out of “fuel”: When fusion stops Heat decreases Pressure decreases GRAVITY WINS! (The star will collapse w/out Pressure pushing outward)

Our sun will be stable for ~ 5 billion more years

•The process that releases energy on stars is called __________________.

•This process takes place in the _________________ of stars.

•This process is initiated when ___________________ pulls most of the nebula’s mass into the center, and temperatures ___________________

•___________________________________________________________

•Fusion starts by combining ________________ atoms (atomic # ____) together to make _________________, (atomic # _____). This process releases enormous amounts of ________________________.

•Fusion continues until heavy elements like _______________ are made. At this point, fusion __________ _______________ and the star will ____________________ or ___________________.

•Fusion does not take place on Earth because…

Interior Layers• Core

Fusion takes place~ 15 million K

• Radiation Zone-Highly compressed gas-Energy travels by being emitted & absorbed as Electromag. waves-1 – 15 mill K-Takes 100,000 yrs for energy to travel through (dense)

• Convection Zone-Hot plasma closer to interior (1 million K) rises, cools (6000 K), and sinks in circular currents

Convection Currents

Surface Layers• Photosphere

- Lower atmosphere- Visible wavelengths- Temps. 6000 K

• Chromosphere- Middle atmosphere- Reddish – H atoms emit energy in red spectrum-Seen at Eclipses- Temps. 6000 – 10 000 K

• Corona- Upper atmosphere- Extends mill. Kms out- Millions of degrees (heated up by solar flares)- Becomes the source of solar wind

Ch. 26.1 Surface Features of the SunA. Sun spots

Cooler, darker regions on sun’s surfaceAssociated w/Magnetic fieldTravel in groups – Move faster @ equatorLast weeks / months

B. Solar ProminencesLoops of hot gas, associated w/sunspots

C. Solar FlaresBursts of X-ray energy & particlesHeat up corona to millions of KParticles form Solar Wind

A

C

B

http://umbra.nascom.nasa.gov/eit/images/Sun_and_earth.jpg

http://www.windows.ucar.edu/tour/link=/sun/images/sunspotnumbers_jpg_image.html

http://www.windows.ucar.edu/tour/link=/sun/images/sunspots_max_min_big_jpg_image.html

Solar Cycle: Pattern of sunspot activity~ 11 year cycleSolar Max Solar Max

Solar Maximum: Peak # sunspotsSolar Minimum: No or few sunspots

Particles from solar wind collide w/ Earth’s magnetic field at poles and create N. Lights (Aurora)

LinksSunspot activity & solar flare reports:www.spaceweather.com

SOHO’s solar images:http://sohowww.nascom.nasa.gov/

What is a solar flare?http://hesperia.gsfc.nasa.gov/sftheory/flare.htm

Why study solar flares?http://hesperia.gsfc.nasa.gov/sftheory/studyflare.htm

Calculating the speed of CMEs: http://sohowww.nascom.nasa.gov/classroom/cme_activity.html

SDAC: http://umbra.nascom.nasa.gov

Label the layers of the sun.

B (Gives off visible light)

C Normally not visible. Gives of red light

A

D

E

F

1. Label the Atmospheric Layers.

2. Give description of each layer.

3. Label the interior layers.

4. Give description of each layer.

Video

• Birth of the Solar System (National Geographic) http://www.youtube.com/watch?v=B1AXbpYndGc

• Massive Solar Storms (National Geographic) http://www.youtube.com/watch?v=DU4hpsistDk&feature=relmfu

• Massive Solar Storms http://www.youtube.com/watch?v=DU4hpsistDk&feature=list_related&playnext=1&list=SL