The Sun.ppt

The Sun is a Rajshahi University's Geography and Environmental Studies Departments presentation.

1. The Sun
TheSunisthemostprominentfeatureinoursolar
system.Itisthelargestobjectandcontains
approximately98%ofthetotalsolarsystemmass.
OnehundredandnineEarthswouldberequiredtofit
acrosstheSun'sdisk,anditsinteriorcouldholdover
1.3millionEarths.
Ageofsunis4.603billionyears.
SunisG2Vtypestar,ayellowdwarfmainsequence
star.

2. The Sun
Mass (kg) 1.989e+30 Mass (Earth = 1)332,830
Equatorial radius (km)695,508 Equatorial radius (Earth = 1)108.97
Mean density (gm/cm
3
)1.409 Mean density (Earth=1)1/4
Rotational period (days)25-36* Orbital velocity (km/sec)230
Revolution (million years) 200 Luminosity (ergs/sec)3.827e33
Magnitude (Vo)-26.8 Mean surface temperature 5500°C
Conversion rate600 (m. metric ton/sec) Energy3.83e+26 (Watts)
Average distance from Earth150 m Km
* The Sun's period of rotation at the surface varies from approximately 25
days at the equator to 36 days at the poles. Deep down, below the convective
zone, everything appears to rotate with a period of 27 days.

3. Principal chemistry
Hydrogen71%
Helium27%
Oxygen0.061%
Carbon0.030%
Nitrogen0.0084%
Neon0.0076%
Iron0.0037%
Silicon0.0031%
Magnesium0.0024%
Sulfur0.0015%
All others0.0015%

4. Principal Internal Balance (Hydrostatic Equilibrium)
ThestructureoftheSundependsonabalancebetweenitsinternal
forces.OneforceholdstheSuntogether.Asecondforcepreventsthe
Sunfromcollapsing.Thisbalanceistechnicallycalledhydrostatic
equilibrium.TheSun’sinwardforcearisesfromitsowngravity.The
outwardforcearisesfromtherapidmotionofitsatoms,amotionthat
givesrisetoapressure.Thus,intheSun,asinvirtuallyallstarsand
planets,thebalanceofhydrostaticequilibriumrequiresthattheoutward
forcecreatedbypressureexactlybalancetheinwardforceoftheSun’s
gravity.Withoutsuchabalance,theSunwouldrapidlychange.For
example,ifitspressureweretooweak,theSun’sowngravitywould
rapidlycrushit.Therefore,tounderstandtheSun,weneedtodiscussin
moredetailhowitspressurearises.

5. Principal Internal Balance (Hydrostatic Equilibrium)
Asketchillustratingtheconditionof
hydrostaticequilibrium,thebalanceof
pressure(bluearrows)and
gravitationalforce(purplearrows)in
theSun.
Sketchillustratingtheperfect,orideal,gaslaw.Gasatomsmove
fasteratthehighertemperature,sotheycollidebothmore
forcefullyandmoreoftenthanatomsinacoolergas.Theseeffects
combinetocreateahigherpressure.Thus,otherthingsbeing
equal,ahottergasexertsagreaterpressure.

6. Interior structure of Sun
1.CoreThe Sun's energy comes from
thermonuclear reactions (converting
hydrogen to helium) in the core,
where the temperature is 15 to 25
million degrees. It covers 25% of Sun
radius.
2.Radiative zoneThe energy
radiates as photon through this
layer. It covers 50% of Sun radius.
3.Convective zone It covers 25% of
outer Sun radius. Then bubbles and
boils to the surface in a process
called convection. Charged particles,
called the solar wind, stream out at a
million miles an hour.

7. Interior structure of Sun

8. Sun spots
Magnetic fields within the sun
slow down the radiation of
heat in some areas, causing
sunspots, which are cool
areas and appear as dark
patches. Average temperature
is 3527
0
celcius. It’s diameter
is 50000 km.

9. Sun’s atmosphere
Photosphere
The lowest region of the sun’s atmosphere.
It can be seen from earth
300-400 km wide
Average temperature 5527
0
Celsius
Chromosphere
2000 km from photosphere to above
The middle layer of the sun’s atmosphere
Average temperature from 4226 to 9727
0
Celsius
Corona
The final or outer layer of the
sun’s atmosphere
From photosphere it extends
several million km
It can be seen best during the
solar eclipse
The average temperature 2
million degree celcius

10. Importance of Sun
Heat and light
Vegetation and animals
Solar energy
Solid and gasses
Minerals
Wind
Ocean current
Water cycle