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 The
sun. The center of our solar system. It gives off heat, light,
and radiation. The sun is actually a ball of glowing gases.
It is hotter than anything we can imagine. It is so hot that
we can feel its heat even though we are 93 million miles away
from it.
If you
could look inside the sun, you would see four different layers:
the core, the radiative zone, the convective zone, and the
photosphere.
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The
core is the center of the sun. Nuclear reactions
take place here, producing energy.
The
radiative zone is the second inside layer. Energy
travels from the core outward to this layer in the form
of radiation.
The
convective zone is the third layer. Huge waves
of energy swirl around here, carrying the heat outward.
The
photosphere is the outside layer of the sun.
This is the visible layer, where light is emitted.
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Producing
Energy (Fusion)
 The
sun produces heat, light, and radiation through the process
of fusion. Fusion occurs when a substance is so hot that atoms
gain and lose particles, actually changing from one type of
element to another. The sun converts hydrogen to helium in
a three-step process.
- Two
hydrogen atoms combine. This forms deuterium, also called
heavy hydrogen.
- Deuterium
joins with another hydrogen atom. This forms a type of helium
(helium-3).
- Two
helium-3 atoms collide, producing ordinary helium and two
hydrogen atoms
Energy
is released at every step. The energy comes in the form of
tremendous heat, radiation that can kill us, and light that
we need to survive.
The
Sun's Role in Life
 The
sun not only produces light, but it allows most other types
of energy to exist. Certainly life on earth wouldn't exist
without the sun. For example, the sun allows plants to make
food in a process called photosynthesis. Photosynthesis allows
for almost all other living organism to survive.
Food
Think about a food chain. A small plant takes the sun's light
(energy) and produces food. The plant is eaten by a tiny little
shrimp. The shrimp is eaten by a fish. The fish is eaten by
you. If the sun died, the food chain would collapse. No plant.
No shrimp. No fish. No you.
Energy
 The
sun also is the source for many other types of energy. For
example, wind energy requires the sun. The sun heats up air
in our atmosphere. The hot air rises. Cool air moves in, and
the air moves around as wind. Or take biomass energy. The
light from the sun grows the plants (trees, corn, sugarcane)
that we use for energy. Or how about solar energy? The sun's
light shines on panels that convert light to electricity.
Fossil fuels? The sun created those too. Sunlight grew those
plants and animals that became oil, coal, and natural gas.
The
Sun's Lifespan
 Our
sun is about 5 billion years old. It is nearly half way through
its life. Five billion years from now the sun will run out
of hydrogen gas. When that happens the sun will grow about
one hundred times bigger than it is right now. And then it
will start to become a white dwarf. Our sun will become a
glowing hot ember, about the size of Earth. It will eventually
cool down.
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