Home Research PapersThis simple as it sounds, as there are many

This simple as it sounds, as there are many

This paper focuses on how
the sun produces heat and light and how that energy is absorbed by the Earth.
Multiple layers of hot gas make up the entirety of the sun; the layers of the
sun that will be discussed include the photosphere, the chromosphere, the
corona, and the core. The core is the area where the most important nuclear
reaction takes place via a proton-proton chain reaction, where the sun turns
mass into energy. This mass-to-energy conversion can be described by one of the
most famous equations in science, E=mc2. Radiation is the sun’s main
way of getting this energy to the Earth. Most of the solar radiation received
is actually absorbed by the Earth, but some of it is reflected back into space.
What is absorbed and how much is absorbed in different areas of the Earth
depends on the angle of the rays of the sun; the more slanted the angles, the
less concentrated sunlight there is, resulting in cooler temperatures.
Radiative equilibrium can occur when incoming solar energy matches outgoing
heat energy, allowing for a relatively stable global temperature. Without the
sun, this temperature would decrease rapidly and continue to decrease until the
Earth was a frozen ball of nothingness. However, the sun does not look like it
is going anywhere any time soon, and thank gravity for that.


            All stars are able to create energy
because they are all, essentially, just massive fusion reactions (Cain). We
just happen to be in the perfect spot to receive the sun’s abundance of energy;
this spot is what is known as the sun’s Habitable Zone (Williams). Getting that
energy from the sun to the Earth is not as simple as it sounds, as there are
many layers of the sun and different processes that must occur in order for
solar energy to get where it needs to go.

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            As stated in the above paragraph, the
sun is composed of multiple layers. The region that we are able to see is what
is known as the photosphere. Temperatures in the photosphere range from about
4500 K to 7500 K (Smith), though the upper part of the photosphere is actually
cooler than the lower part. Because of this, a phenomenon known as limb
darkening occurs causing the sun to appear brighter in the center (Cain). It is
also in this layer where the energy from the sun is released to us as heat and

            The chromosphere is above the
photosphere, ranging from 5000 K to upwards of 100,000 K; this part of the sun
is visible to us only when a solar eclipse occurs, which is also true for the
corona. The corona lies above the chromosphere, reaching temperatures of up to
a boiling 2,000,000 K (Smith).

            Sunspots are darker and cooler areas
that appear in the photosphere and can vary in size, reaching up to 50,000
kilometers in diameter (University of California). The abundance of sunspots is
related to the brightness of the sun; the brighter the sun, the more sunspots
that appear. According to the University of California, San Diego, “it has to
do with changes in the magnetic field of the sun and with convection within the
outer layer of our star (not with processes in the core).” Solar flares are
also produced in the photosphere and can produce bursts of ultraviolet
radiation and electromagnetic radiation (Sharp).

            Radiation is the primary way the sun’s
energy travels across space to reach the Earth’s atmosphere. According to the
Ohio State University, “about 43 percent of the total radiant energy emitted
from the sun is in visible parts of the spectrum.” The upper layer of the
atmosphere of the Earth filters most of the sun’s ultraviolet radiation,
however, what passes through is absorbed by the Earth, and, in return, is what
heats our planet (Ohio State University).

            The average amount of solar
radiation that is absorbed by the Earth is 70 percent, which means that 30
percent of that is reflected back into space. The intensity of this solar
radiation is largely due to the angle that the sun’s rays strike the Earth
(Ohio State University). At the equator, for example, the intensity is constant
because the angle of the rays is more concentrated, whereas in the North and
South poles, the angle of the rays is more slant, thus dispersing more of the
sunlight. Other factors that make certain areas colder or hotter than others depend
upon the concentration of air molecules and small particles in the atmosphere.
At higher latitudes, the sun’s path is longer, so there will be more air
molecules and small particles for the sunlight to travel through, resulting in
less solar energy reaching certain areas (Yung). Earth will reach radiative
equilibrium when the flow of incoming solar energy is equal to the flow of
outgoing heat energy, resulting in a relatively stable global temperature. (Ohio
State University).

            We know that the sun and the Earth
work together to sustain life and that the sun’s light and heat energy travels
through the Earth’s atmosphere and gets absorbed by the Earth, but how exactly
does the sun, alone, come up with all of its energy? The sun is just a huge
ball of hot gas, most of which is hydrogen, making up about 70 percent of the
sun. The sun is also constantly turning this hydrogen into helium through a
process called nuclear fusion (Cool Cosmos). This process is able to take place
because of just how hot and how much pressure resides in the core of the sun. The
most important nuclear reaction in a bright
star is the carbon-nitrogen cycle. However, since our sun is more of dim
star, it uses the proton-proton chain reaction instead (Hong Kong Observatory).

            The process begins with a proton
that fuses with another, and then transforms into a neutron by way of the
weaker nuclear force. As the neutron is formed, so is a positron and a neutrino;
this pairing between the positron and the neutrino is known as a deuterium.
Then, a third proton collides with the deuterium, resulting in a helium-3
nucleus and a gamma ray. The gamma ray works its way from the core to the outer
regions of the sun and is released as sunlight. After the formation of two
helium-3 nuclei, they will collide with one another to create a helium-4
nucleus. This helium-4 nucleus contains less mass than the original four
protons that came together, thus resulting in an excess amount of energy being
released in the form of heat and light. According to Energy Education, “of all
the mass that undergoes this fusion process, only about 0.7% of it is turned
into energy.” That may seem like a miniscule amount of mass, but it is equal to
4.26 million metric tons that are being converted into energy every second

            This mass-to-energy conversion can
be described by the formula E=mc2, where E is the kinetic energy of
a body, m is the mass, and c2 is the speed of light squared. This
equation states that mass and energy are, effectively, the same thing. The
energy created by the nuclear fusion process exerts outward pressure, and
unless it is contained, the pressure will result in an explosion. What keeps a
star (or our sun) from exploding is the gravitational attraction of the gas
mantle surrounding the core (University of California).

            What keeps us and our planet alive
is the sun and its heat and light energy that it so “willingly” provides for
us. We can only imagine what would happen if the sun were to disappear. To say
the least, life on Earth would look very sad indeed; it has been theorized that
temperatures would drop rapidly, and the atmosphere itself would freeze,
“leaving us exposed to the harsh radiation travelling through space”
(O’Callaghan). Thankfully, we should not have to worry about that in our


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