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What is a Sun? The Sun is a seething ball of extremely hot gas.
The Sun has survived for about 5 million years, and will likely survive
for another 5 billion. The sun is not on fire, will never explode, and
a solar flare will never destroy the Earth. the Sun is 93 million miles
away. So, if we drove 93 miles per hour the trip would only take us 1 miles
per hour. "How long is 1 million hours?" One year is 365 days times 24
hours per day, or 8,760 hours. One hundred years would be 876,000 hours,
still a little short of the 1 million hour drive time--so the Sun is really
quite far away. The Sun is hundreas of times more massive than all the planets
in the Solar System combined. However, the Sun itself contains only a small
amount of the total angular momentum of the Solar System. Passing so close to
the Sun, sungrazers are subjected to destructive tidel forces along with
intense solar heat.
After steadily sinking in Northern Hemisphere skies, the Sun is now at its
lowest declination - marking the first day of Northern Winter (but Southern
Summer!). The Earth is actually closer to the Sun during this season, a fact
not usually appreciated by those who dwell on the planet's Northern half.
The Sun is the most prominent feature in our solar system. It is the largest
object and contains approximately 98% of the total solar system mass. One
hundred and nine Earths would be required to fit across the Sun's disk, and
its interior could hold over 1.3 million Earths. The Sun's outer visible layer
is called the photosphere and has a temperature of 6,000°C. This layer has a
mottled appearance due to the turbulent eruptions of energy at the surface.
Solar energy is created deep within the core of the Sun. It is here that the
temperature (15,000,000° C) and pressure (340 billion times Earth's air pressure
at sea level) is so intense that nuclear reactions take place. This reaction
causes four protons or hydrogen nuclei to fuse together to form one alpha particle
or helium nucleus. The alpha particle is about .7 percent less massive than the
four protons.
The difference in mass is expelled as energy and is carried to the surface of
the Sun, through a process known as convection, where it is released as light
and heat. Energy generated in the Sun's core takes a million years to reach its
urface. Every second 700 million tons of hydrogen are converted into helium ashes.
In the process 5 million tons of pure energy is released; therefore, as time goes
on the Sun is becoming lighter.The chromosphere is above the photosphere. Solar
energy passes through this region on its way out from the center of the Sun. Faculae
and flares arise in the chromosphere. Faculae are bright luminous hydrogen clouds
which form above regions where sunspots are about to form. Flares are bright filaments
of hot gas emerging from sunspot regions. Sunspots are dark depressions on the photosphere
with a typical temperature of 4,000°C.
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