Download The Sun PPT

The Sun?
The Sun is a star! There are
an incredible amount of
stars in the universe. Yay!
What is a star…?
A star is a huge sphere of very hot, glowing gas. Stars produce
their own light and energy by a process called nuclear fusion.
Fusion happens when lighter elements are forced to become
heavier elements. When this happens, a tremendous amount of
energy is created causing the star to heat up and shine. Stars
come in a variety of sizes and colors. Our Sun is an average sized
yellowish star. Stars which are smaller than our Sun are reddish
and larger stars are blue.
Useful Links:
http://science.nationalgeographic.com/science/space/universe/stars-article/
http://www.universetoday.com/24351/what-is-a-star/
http://imagine.gsfc.nasa.gov/docs/science/know_l2/stars.html
The Sun – Our Star
• One of many stars in the Milky Way, but
extremely important to us…why?
– Provides energy, helps in understanding other
stars b/c they’re too far away
Solar Data
• The diameter of the Sun is thus 109 times as
great as the Earth's diameter.
• About 1.3 million Earths could fit inside the sun.
• The mass of the sun is 2 x 1030 kilograms,
about 332,000 times the mass of the Earth.
• Volume of the Sun is about 1.5 million times that
of Earth’s
• Mean density of Sun = 1408 (kg/m3)
• Mean density of Earth = 5514 (kg/m3)
Solar Parts
• A ball of gas, which can be generally thought
of as having four “layers”:
– Solar interior (core, radiation zone, convection
zone)
– visible surface (photosphere)
• ‘visible’ ‘layer’
– two atmospheric components
• chromosphere
• corona
Photosphere
• Appears orange due to granules
– size of Earth and only last 8-10 minutes
– ‘boiling effect’ cause by circulation of energy in
the convection zone
Solar Activity
Composition surface = 74% Hydrogen, 25% Helium,
1% other
Sunspots: dark regions on the Sun that are slightly cooler than
surrounding surface, and are associated with very strong magnetic
activity.
Sunspots
• Observed throughout antiquity (try looking at the
sun at its lowest point in the sky, or through a
cloud bank and you can occasionally see them
unaided)
• Deduction of Solar Rotation rate and differential
rotation nature from sunspot observation
• Dark spot? Not really. Many X brighter than Full
Moon. Its relative.
• Plage = lighter areas around the sunspots
Chromosphere
• Layer above the photosphere
• Not visible to the naked eye
• Hot, low density gas produces an emission
spectrum
• Appears red due to concentration of hydrogen
gases
The Corona
• Only visible when the solar disc is covered
(during a solar eclipse or with a coronagraph)
• Very hot, High energy, low density particles
escape the gravitational pull of the Sun
• Released as streams of ions and radiation
outward from the Sun = Solar Wind
Sunspots
Prominences/Flares
• http://www.space.com/25287-major-solarflare-eruption-video.html
• http://www.space.com/25291-sun-sticks-outa-tongue-of-super-heated-plasma-video.html
• http://youtu.be/wisdfag6WIQ
Prominences/Flares
• Flares are massive eruptions from the surface
of the Sun resulting in huge amounts of
charged particle energy ejected into space
(CMEs – Coronal Mass Ejections)
• Threating to astronauts, damaging to
communication systems
• Kill shot? Radio/X-Ray/UV radiation
• Prominences are large looping structures of
solar material tapped by magnetic fields.
Aurora Borealis/Australis Colors
Solar Interior
Missing Matter -> Energy
• Matter is converted to energy according
to Einstein's famous formula:
– E = mc2
• c = speed of light (3x108m/s)
• M = mass (kg)
• E = energy (Joules [J])
– A Joule is a unit of energy equivalent to the energy
needed to apply a force of 1 Newton through a
distance of one meter.
How much energy in matter?
The equivalent of energy that would be produced by burning 1000 tons
of coal!!
Solar Fusion
• 4 million tons of Hydrogen converted to
energy every second in Solar core!
• This consumes 600 million tons of Hydrogen
“fuel” every second!
• How long can such fuel consumption keep up
before the Sun run’s out?
• At present rate: about another 100 billion
years!! Conclusion?
Solar Fusion
• The Sun can last for a long time, however it will
not last for another 100 billion years
• In about 4.5 billion years, the Sun will swell into a
Red Giant star.
• This will happen b/c the Sun has run out of
Hydrogen fuel in its core, resulting in less
outward pressure and gravitational contraction,
leading to increased pressure/temp. and fusion of
heavier elements.