The sun is our star which is located in our solar system which contains of 9 planets and one star called sun which we will
talk about it here.
The sun is G2 star
and sun is one of the more than bilion(1e9) starsin our galaxy.
Diameter:1.4 million km
Solar Cycle:8 - 11 years
Mass:330,000 x Earth
Distance from Earth:149.6 million km (93 million miles)
Distance to Nearest Star:4.3 light years
Solar Wind Speed:3 million km/hr.
Temperature at surface:5,500 Degrees C (9,932o F)
Temperature at Core:14 million Degrees C (22.5 milliono F)
Temperature of Sunspots:4,000 Degrees C (7,232o F)
Rotation Period at Equator: 25 Earth days
Rotation Period at Poles:35 Earth days
Luminosity:390 billion billion megawatts
Age:4.5 billion years
the sun by mass is largest object in the solar system it contains more than 99.8% of the total mass of the solar system.
the sun is at preasent about 75% hydrogen, 25% helium by mass and 92.1%hydrogen,7.8% helium by number of atoms
others else 0.1% and it changes slowly over time as the sun converts hydrogen to helium in its core
each second 700.000.000 tons of hydrogen are converted to about 695.000.000 tons of helium and 5.000.000(3.86e33 ergs) tons of energy in the form of gamma rays
the outer layers of the sun exhibit differential rotation. at the equator the surface rotates once every 25.4 days near poles it's as much as 36 days
this odd behavior is due to the fact that the sun is not solid body like the earth.
the differential rotation extends considerably down into theinterior of the sun but the core of the sun rotates as a solid body.
-what makes sun lights?
as we know the centre of the sun is very hot and the pressure is immense(about 100 billion times the air pressure here on earth)
because of that,atoms come so close to each other that they fuse.
light of the sun
and you have to know that in every second the sun spends 700 billion tons of protons (or hydrogen)
in this way.
and only a small fraction (0.7 percent) is turned into light.
the sun energy output 3.8e33ergs/second or 386 billion mega watts and this produced by nuclear fusion reactions.
it's the surface of the sun is at a temperature of about 5800 k.
they are cool regions only 3800 k. and they look dark only by comparison with surrounding regions.
sun spots can be very large as much as 50.000 km in diameter.
sun spots is caused by complicated and not very well understood in teroactions with the sun magnentic field and the magnatic field is much higher than else where.this increases the "magnetic pressure" which in turn
decreases the normal atmospheric pressure,and because of that,the temperature in the sun spots is lower than the surrounds area.
the small region lies above phtosphere or by other meaning lies just outside the photosphere,and is almost completely transprant.on the picture in the right side you can see the chromosphere as a red glow just a round the sun.
if you closely ,you'll also see solar flares in the chromosphere.on the picture at left you can see very large example .
the corona begins at the top of the atmosphereand extends million of kilometers into space but is visible only during eclipses.because the corona is so thin.the corona can be seen at the image to the left.
the temperature of the corona is very high:about a million(1.000.000) degrees.it is so hot that it emits light at x-ray wavelengths;the picture to the right is an"x-ray photo" of the sun.
and you have to know that it still isn't well known how this can be:how can the surface of the sun be only 6000 degrees,while the area about it is much hotter?it probably has to do with the coplicated magentic fields of the sun.
in addition to heat and light ,the sun also emits a low density stream of charged particles(mostly electrons and protons)knowm as the solar wind which propagates through out the solar system at about 450 km/sec. with a temperature of about a million degreesand this solar wind reaches out to at least the distance of the voyager 2 space prope and that is beyond pluto's orbit at about 5914 millon kilometers.
the orgin of the solar wind lies in the sun's corona.the solar wind blows gas and dust oozing out of cometary nucleus backward,creating the characteristic 'tails'of comets.this can be seen in the picture at right.
the solar wind and the much higher energy particles ejected by solar flares can have drametic effects on the earth ranging from power line surges to radio interference to the beautiful aurora borealis.
to study the solar wind,the european space prope ulysses has been launced.
due to its unique orbit,it can for the first time study the north and the south polar regions of the sun.it has shown that the solar wind is very irregular,and much faster near the polar regions of the sun that at equatorial latitudes.
the grainyness you see in this picture called granulation,and the is called by the convection,or by 'bubling' of the sun.
how large do you think each cell is?the size of a football field?or manhatten?or france?
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Last Modified : 5 Sep. 2001
Created By#C0115361 Team