The+Sun

While many astonomores refers to our as a 'typical' ordinary' star,it is brighter,larger,and more massive than the majority massive than the majority of stars.

sun's diameter(distance Across)is 1,400,000km that is nearlly 4times the disatnce to our moon Sunscircumference=4 million km suns mass=1000times that of jupiter amd 300000 times the mass of earth

suns mass compared to the earths is like comparing 3 NFL linebackers to a paperclip 99.9% of the atoms in the sun are either Hydrogenor helium if you could create an Earth-sized planet with it You could do the same with the suns copper,silicon,chlorine,fluorine,potassium,and many element Gold ranks 77 in the order of elemnts in the sun, but you could take all the gold and plate the earth to a thickeness of 100m Energy output of tehsun=4x10^26 watts if one second worth of the Suns energy every

Until the mid-19th centruy,not much though wasa given to how the Sun produces it energy, as knowledge of physics and chemistry was limited William herschel(leading astronomer of his time) suggested that sunspots were holes in the Suns fiery clouds, threough which he could see a cool surface "lush with green vegetation" the idea that the sun is burning has been around since anicent times. Combustion, a chemiacl reaction,can produce a great deal of oxygen, the sun could have remained burning for only 2000 years Lord Kelvin, in 1862, suggested that the brightness of the sun was from metrioc impacts. objects falling into the sun accelerate and their energy is converted to heat and light We now know that it would take about 1/10th of the mass of the earth stricking the sun everyyear to pruduce that amount of heat and light If that much mass were stricking the sun every year, it would now be seen via telscope,and that increase in mass of the sun would have a greater graviontal effect on the entire solar system,changing orbits. Gravitaional contraction 19th centruy idea as to the source of the sun's power was that it was slowly falling in on itself due to its own gravity This is the source of the luminosity of both jupiter and neptune problem with this idea is that the sun couldnt have been doing so for long enough if the sun began as a widely dispersed cloud of gas and then shrank to its present size, the total energy released would only be enough for 20 million years This amount of time(20mil yrs) for the sun to have shrank to its present size is called the Kelvin-Helmoholtz time When this thoery was prposed, 20million years was belived to be enough time to account for the history of the solar system we now know that the sun Nuclear Reactions Beginning of the 20th centruy- realization that vast amounts of energy could be released in nuclear reactions According to Einstein's formula E=mc^2 fission of even a small amount of matter could yeild large amounts of energy 1 kg of fissionable material yeild about 1 million times as much as 1kg of combustible material. While fission seemed like possible explantion for the suns energy, the amount of fissionable material in the sun is relatively low. Uranium makes up only about one in ever 10^12 atoms. Fission of Uranium could only power the sun for about 2 months The process involved in powering the sun had to deal with the elements that are abundant in the sun. 1920-A.S. Eddington prposed that the process fueiling the sun was the fusion of Hygrogen in Helium. It took 20 years to work out all the details.