Transcript The Sun (power point) by Ms. Kimball the_sun_pp

• Our sun is a star
located at the center
of our Solar System.
It is a huge, spinning
ball of hot gas and
nuclear reactions that
lights up the Earth
and provides us with
heat.
Fun Facts
• AGE OF THE SUN
The Sun formed 4.5 billion
years ago, as the solar system
coalesced from a cloud of gas
and dust.
Our sun is a medium-sized
yellow star that is 93,026,724
miles from the Earth.
• The Earth is closest to the Sun
(this is called perihelion)
around January 2 each year
(91.4 million miles = 147.1
million km); it is farthest away
from the Sun (this is called
aphelion) around July 2 each
year (94.8 million miles =
152.6 million km).
Warning
 NEVER LOOK
DIRECTLY AT
THE SUN!
Looking at the
Sun can blind
you or cause
cataracts.
• Our Sun is a second or third generation
star. Second generation stars do not just
burn hydrogen, they also burn heavier
elements, like helium and metals, and
were formed from supernova explosions.
• supernova = an exploding star
Structure of the Sun
Structure of the Sun
The Core

The temperature is
roughly 15 million °C.
At this temperature,
nuclear fusion occurs,
turning four hydrogen
nuclei into a single
helium nucleus plus a
LOT of energy.
Nuclear Fusion

Nuclear fusion is an
atomic reaction in
which many nuclei (the
centers of atoms)
combine together to
make a larger one
(which is a different
element).
• The result of this
process is the release
of a lot of energy.
(Suns are powered by
nuclear fusion, mostly
converting hydrogen
into helium. In this
process, 4 hydrogen
nuclei combine to form
a single helium
nucleus; about 0.3%
of the original mass is
converted into energy.
• Although the nuclear output of the sun is not entirely consistent,
each second the Sun converts about 600,000,000 tons of hydrogen
nuclei into helium nuclei.
• These fusion reactions convert part of these atoms' mass (roughly 4
million tons) into energy, and release an enormous amount of this
heat and light energy into the Solar System.
• In these fusion reactions, the Sun loses 4 million tons of mass each
second.
• The Sun will run out of fuel in about 5 billion (5,000,000,000) years.
When this happens, the Sun will explode into a planetary nebula, a
giant shell of gas that will destroy the planets in the Solar System
(including Earth).
Radiation Zone
• The next layer out from
the core is this zone
which emits radiation.
This radiation diffuses
outwards. The
temperature ranges from
15 million °C to one
million °C. It may take
photons of radiation
millions of years to pass
through the radiative
zone, as they gradually
make their way outwards.
The Convective Zone
• The Convective Zone: In
this next layer, photons
continue to make their
way outwards via
convection (towards
lower temperature and
pressure). The
temperature ranges from
one million °C to 6,000
°C.
CONVECTION
Convection is the transfer
of heat by circulation
through a gas or liquid.
The Chromosphere
• The Chromosphere: This
reddish layer is an area of
rising temperatures. The
temperature ranges from 6,000
°C (at lower altitudes) to
50,000 °C (at higher altitudes).
This layer is a few thousand
miles (or kilometers) thick. It
appears red because
hydrogen atoms are in an
excited state and emit
radiation.
• The Chromosphere is visible
during solar eclipses
The Photoshpere
• This is the lower
atmosphere of the
Sun and the part that
we see (since it emits
light at visible
wavelengths). This
layer is about 300
miles (500km) thick.
The temperature is
about 5,500 °C.
The Corona

This is the outer layer of
the Sun's atmosphere.
The corona extends for
millions of miles and the
temperatures are
tremendous, reaching
one million °C.
The Quiz

1. Is the Sun a star, a planet, or a nebula?
2. Is the Sun solid, liquid, or gaseous?
3. During what month is the Sun closest to the
Earth?
4. Where is the Sun hottest?

5. Where is the Sun coolest?
6. What element is most plentiful on the Sun?
7. What element was named after the Sun?
8. What is the primary atomic reaction that occurs
within the Sun that converts hydrogen atoms into
helium atoms?

9. How old is the Sun?
10. Are sunspots hotter or colder than the surrounding
areas?