Essay: Discussion on Astronomy
Essay: Discussion on Astronomy
Discuss the prospects for utilizing solar energy on Earth and discuss solar energy advantages and disadvantages over fossil fuels (oil and coal)?
The annual solar radiation at the surface of the earth is over 10000 time’s primary global energy consumption. Large solar plants can be used to produce electricity cheaply. Photovoltaic cells can be installed on buildings to produce clean energy on individual basis. Advantages of solar energy as compare to fossil fuels are that it is environmentally clean and it’s easily available. Its major disadvantage is its unavailability due to bad weather and at nights which introduces challenge of storing massive amount of energy in solar plants to be used when the Sun is not available (Bennett, Donahue, Schneider & Voit, 2000).
Why do massive stars have much shorter lives than low mass stars? What is the fate of a star of about 1 Solar Mass as it starts to leave the Main Sequence? What is the fate of a star that is 10 solar masses after it leaves the Main Sequence and thereafter. Assume both star entered the main sequence at the same time, which star will have a higher luminosity after 1 million years, after 200 million years, after 2 billion years? In this comparison which star do you think would be most suitable for supporting life as we know it. Explain you reasoning.
Massive stars have shorter lives because they burn faster and produce more energy due to their larger size as compare to others. When a star leaves the main sequence it grows into a red giant and then turn into white dwarf which later becomes a dark dwarf. A star having a mass of 10 suns will turn into a red giant, and then becomes a white dwarf, but will explode into a supernova after sometime as it reaches critical mass (Kutner, 2003).
The interior of a main sequence star is best described as a Nuclear Reactor, a place where energy releasing nuclear reactions occur under tremendous temperatures. As more nuclear reactions occur the solar core should get hotter and hotter, therefore the rate of fusion, which depends on temperature, should increase further, eventually leading to a run away effect. In conclusion Stars should be unstable; in fact they ought to blow up like atomic bombs!
What is wrong with this logic? What processes keep the core of main sequence stars remarkably stable? How many tons of Hydrogen does the Sun convert to Energy in a single Earth day. How much energy does this correspond to using E = mc^2.
The hydrostatic equilibrium keeps the star stable. That means that although the increase in reaction increase the temperature of the core, but it also cause the star to expand until the gravity balances the thermal pressure. This increase is size, also cause the decrease in temperature in the core which reduces the rate of fusion reaction, thus bringing stability to the star. Also, the Sun converts 4.32 × 1011 metric tons of hydrogen into energy each day (Reike, 2009).
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