x Solar wind is a stream of charged particles continually blown outward in all
directions from the Sun.
x It helps shape the magnetosphere of planets and blows back the material that forms
the plasma tails of comets. It also cleared away the gas of the solar nebula.
x The corona LVWKHRXWHUPRVWOD\HURIWKHVXQ¶VDWPRVSKHUH,WVWHPSHUDWXUHEHing 1
density is extremely low.
x The chromospehere is the middle layer of the solar atmosphere and the region that
UDGLDWHVPRVWRIWKH6XQ¶VXOWUDYLROHWZLWKDWHPSHUDWXUHRI about 10,000 K.
x The photosphere is the lowest layer of the atmosphere, which is the visible surface
of the Sun. Its temperature is about 6,000 K and it is where sunspots are found.
x The convection zone is where energy generated in the solar core travels upward,
transported by the rising of hot gas and falling of cool gas, a process called
x The radiation zone is where energy moves outward primarily in the form of
photons of light. The temperature is about 10 million K with predominant X rays.
x The solar core is where nuclear fusion transforms hydrogen into helium. The
temperature is about 15 million K with 100X the density of water and pressure that
is 200-billionX that on the surface of Earth.
The Cosmic Crucible
x Nuclear Fission ± the process of splitting a nucleus into two smaller nuclei.
x Nuclear Fusion ± the process of combining nuclei to make a nucleus with a greater
number of protons or neutrons.
x Human-built nuclear power plants rely on nuclear fission of uranium or plutonium.
x The nuclear power plant of the Sun relies on nuclear fusion, turning hydrogen to
Nuclear Fusion in the Sun
x Fusion occurs within the Sun, because of positively charged atomic nuclei in the
solar core moving at high speeds, colliding with one another.
x In most cases, electromagnetic forces deflect the nuclei, preventing collisions,
because positive charges repel one another.
x A collision with sufficient energy will stick together to form a heavier nucleus.
x Sticking positively charged nuclei require strong force (can overcome positive
repulsion), which binds protons and neutrons together in atomic nuclei.
x The strong is like glue/Velcro ± overpowers the electromagnetic force over very
x Nuclear fusion is to push the positively charged nuclei close enough together for
the strong force to outmuscle electromagnetic repulsion.