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Earth Science 24.3B The Sun’s Interior. The Solar Interior. Earth Science 24.3 The Sun. The Solar Interior: The interior of the sun can not be observed directly.
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Earth Science 24.3B The Sun’s Interior The Solar Interior
Earth Science 24.3 The Sun The Solar Interior: • The interior of the sun can not be observed directly. • For that reason, all that we know about it is based on information acquired from the energy it radiates and from theoretical studies.
Earth Science 24.3 The Sun Nuclear Fusion: • Deep in it’s interior, the sun produces energy by a process known as nuclear fusion. • This nuclear reaction converts four hydrogen nuclei into the nucleus of a helium atom.
Earth Science 24.3 The Sun • During nuclear fusion, energy is released because some matter is actually converted to energy. • How does the process of nuclear fusion work?
Earth Science 24.3 The Sun • Consider the four hydrogen atoms have a combined atomic mass of 4.032 atomic mass units ( 4 X 1.008) whereas the atomic mass of helium is 4.003 atomic mass units. ( a difference of 0.029 units) • This tiny difference is emitted as energy according to Einstein’s equation ( E = mc2).
Earth Science 24.3 The Sun • According to Einstein’s equation, seen at right, E equals energy, m equals the mass, and c equals the speed of light. E = energy M = mass C = speed of light (300,000 mp/s)
Earth Science 24.3 The Sun • Because the speed of light (c) is great (300,000 kilometers per second), the amount of energy released from even a small amount of material is enormous. • The hydrogen bomb the United States military developed was made possible by creating such a reaction.
Earth Science 24.3 The Sun • The conversion of just one pinheads worth of hydrogen to helium generates more energy than burning thousands of tons of coal. • Most of this energy is in the form of high-energy photons that work their way toward the solar surface. • The photons are absorbed and reemitted many times until they reach a layer just below the photosphere.
Earth Science 24.3 The Sun • Here, convection currents help transport this energy to the solar surface, where it radiates through the transparent chromosphere and corona. • Only a small percentage of the hydrogen in the nuclear reaction is actually converted to energy.
Earth Science 24.3 The Sun • Nevertheless, the sun is consuming 600 million tons of hydrogen each second; about 4 million tons are converted to energy. • As hydrogen is consumed, the product of this reaction, helium, forms the solar core, which continually grows in size.
Earth Science 24.3 The Sun • Just how long can the sun produce energy at it’s present rate before all of it’s hydrogen fuel is consumed? • Even at the enormous rate of consumption, the sun, has enough fuel to last easily for another 100 billion years.
Earth Science 24.3 The Sun • However, evidence from observing other stars indicates that the sun will grow dramatically and engulf the Earth long before all of it’s hydrogen is gone. • It is thought that a star the size of the sun can exist in it’s present stable state for 10 billion years.
Earth Science 24.3 The Sun • As the sun is already 4.5 billion years old, it is “middle aged” at present.
Earth Science 24.3 The Sun • For fusion to occur however, the sun’s internal temperature must have reached several million degrees. • What caused this increase in temperature?
Earth Science 24.3 The Sun • The solar system is believed to have formed from an enormous compressed cloud of dust and gases, mostly hydrogen. • When gases are compressed, their temperature increases due to the higher pressure they are under.
Earth Science 24.3 The Sun • All of the bodies in our solar system are compressed. • The sun however, because of it’s enormous size, was the only object to become hot enough for nuclear fusion to occur. • Astronomers currently calculate it’s internal temperature at 15 million degrees Kelvin (K).
Earth Science 24.3 The Sun • The planet Jupiter is basically a hydrogen-rich ball as well. • If it were about 10 times more massive, it too would have converted into a star capable of nuclear fusion.
Earth Science 24.3 The Sun • The idea of one star orbiting another seems odd but recent evidence indicates that about 50 percent of the stars in the universe occur in pairs or multiple stars within a single system.