

The sun is believed to be roughly 4.6 billion
years of age.
Early scientist use to believe that the sun
generated its energy by burning fuel.


This process could not produce enough energy to
power the sun.
The sun would have only lasted for 10,000 years.


Later scientist thought that gravity was causing
the sun to slowly shrink.
They thought that gravity would release
enough energy to heat the sun.

If this were to occur the sun would have only lasted
for 4.5 million years.






Albert Einstein showed that matter and energy
are interchangeable.
E=mc²
E = energy
m = mass
c = speed of light
Because c is such a large number small
amounts of matter could create large amounts
of energy.

Nuclear fusion – the process by which two or
more low-mass nuclei join together, or fuse, to
form another nucleus.

Example 4 hydrogen nuclei fuse to form a single
helium nucleus.


Hydrogen ions are positive charges that are
repelling to each other.
But how do they fuse?

Temperature and gravity are very high inside
the sun resulting in the nuclei overcoming the
repulsive forces.


Hydrogen fuses into helium.
Light in the core takes millions of years to
reach its surface due to the large amount of
energy in the radiative zone.

1.
2.
3.
Hydrogen Atoms are stripped of their electrons
due to the extreme temperatures and pressures
in the sun.
Due to the exposure of the nucleus when the
atoms combine they can exchange the protons
left inside.
One of the protons changes into a neutron.
Another proton combines with the p-n pair
producing a nucleus made of 2p and 1n.
4. Two of these nuclei combine and fuse.
5. Two protons are thrown out leaving behind 2p
and 2n aka helium.

http://www.astro.ubc.ca/~scharein/applets/
Sim/fusion/Fusion.html


The Sun is responsible for 99% of the solar
systems mass.
Large ball of gas made up of mostly hydrogen
and helium which is held together by extreme
forces of gravity.


The sun does not have a solid structure.
You actually can see through the outer layer of
the sun.

Visible layer is the layer in which the gas becomes so
thick that you cannot see through it.


The splitting of an atom into two parts.
How does this process provide energy?


Energy is produced when an alpha particle is
ejected from the Uranium-235 to split it into
two lighter elements.
This occurs naturally.


Alpha Particle – a particle that consist of 2
protons and 2 neutrons that is ejected during
radioactive decay.
http://science.howstuffworks.com/insidenuclear-power-plant-pictures.htm

The sequence of (exothermic chemical
reactions) heat releasing reactions between a
fuel and an oxidant accompanied by the
production of heat.


Produces light and heat.
Typical reaction:

CH4 + 2O2 -> CO2 +2H20 + ENERGY


“Twinkle, Twinkle Little Star”
Stars don’t “twinkle”- the atmosphere causes
starlight to shimmer and blur and look like it’s
twinkling



Light gathered by telescopes on the Earth’s surface is
affected by the atmosphere
On Earth- top of mountain is good location for
telescope because of thinner air
Best place- Space because no atmosphere to
interfere with light

Due to Earth’s atmosphere the following
wavelengths of light are blocked:

Radiation – The form in which energy is
released from the Sun and travels through
space.

All of the wavelengths of electromagnetic radiation
Invisible
Invisible
LONG
ROYGBIV
Visible portion
SHORT

Ultraviolet (UV) wavelengths have the greatest
energy out of the energy that reaches Earth’s
surface.

Only about 7% of solar radiation is in the UV
wavelengths.

The three types are:



• UVC: the highest energy ultraviolet, does not reach
the planet’s surface at all.
• UVB: the second highest energy, is also mostly
stopped in the atmosphere.
• UVA: the lowest energy, travels through the
atmosphere to the ground.

The remaining solar radiation is the longest
wavelength, infrared.


Most objects radiate infrared energy, which we feel
as heat.
Some of the wavelengths of solar radiation traveling
through the atmosphere may be lost due to
absorption by Earth’s ozone layer, O2, CO2, and
H2O.

The transfer of energy from the Sun across
nearly empty space (remember that space is a
vacuum) is accomplished by radiation.

Radiation is the transfer of energy by
electromagnetic wave motion.

The unpredictable path a photon takes to get
out of the Sun’s radiation zone.

Can take millions of years to escape the Sun due to
its density.
 Example: Attempting to walk through a crowded
subway station blindfolded.