Question

Speech on stellar evolution [so that I can say it in my school]

Answer 1

Life on Earth would not have been possible were not for the process of star formation that has been continuously occurring since the Universe began to expand some 13-15 billion years ago. Each star evolves in a slightly different way depending on the initial mass of the star. Stars begin their life as a vast cloud of dust and gas (mostly hydrogen gas). Gravitational forces bring these particles and gases together until the conversion of gravitational potential energy to heat causes the temperature to raise enough to allow hydrogen fusion. Once hydrogen starts fusing into helium, a star is born.While all stars form in the same way, the path a star takes to its eventual death is not always the same. How a star ends its life is dependent on its initial mass. Low mass stars (about five times the mass of the Sun or less) will evolve and end their life as a white dwarf. Intermediate mass stars (five to ten times the mass of the Sun) will evolve and end their life as a neutron star while the most massive stars become black holes.Life on Earth owes its existence to the process of stellar evolution, for without it our sun would never have been created and therefore never have been able to bathe out planet with its life giving energy. It should be noted, though, that it is this same process of star formation and death that will some day be the demise of the Earth and all life on it. Current measurements suggest that the Sun is halfway through its ten billion year life cycle. It has continuously increased its heat energy output over the past 5 billion years and will continue to for the next 5 billion years.hope it helped...