The SUN & comparision of sun with earth

 Sun

                       

The sun is fairly an orinary star of spectral type G2V and with a madnitude of 4.8.However ,is proximity to the earth makes it of most immediate interest to us also most accessible for styudy.The vital statistics of the sun are follows;

Age=4.5*10 ⁹  year

Mass=1.99*10 ³⁰  kg

Radius=696000 km

Mean density=1.4*10 ³  kg/m ³

Mean distance from earth=150*10 ⁶  km

Surface gravity=274 m/s

Escapevelocity at surface=618 km/s

Luminosity=3.86*10 ²⁶ W

Equtorial rotation period=26  days

Mass loss rate=10 ⁹ kg/s

Effective black body temperature=5785 k

Inclination of sun’s equator to plane of earth’s orbit=7 ⁰

Composition;  Approximately 90% H, 10%  He,0.1% other elemente like C, N, O…..etc

COMPARISON OF SUN WITH EARTH:

         Inoeder to put some of these figures into perspective,we may note that the sun’s mass is 330000 times that of earth, and its radius is 109 times larger.The mean density of earth is only about 4 times that of the sun,the atmospheric density at surfece of earth is 1 kg/m ³ .which makesthe earths sea level atmospheric pressure five times the suns surface pressure.One astronomical unit (AU) is only 215 times of the radius of the sun and it takes sunlight 8 min to reach the earth.the suns emmitted radiation amounts to 1kW/m ²  at the surface of earth.the surface gravityis 27 times greater at the sun,and the suns rotation produces an equatorial velocity of 2 Km/s.

 

The sun is a massive ball of gas held together ans compressed under its own gravitational attraction.It consists primarly of H and He.Theses gases ar% of the mass of the sun and are present roughly the sameproportion s on the earh.

         

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