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23 Cards in this Set
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In the late 1800s, Kelvin and Helmholtz suggested that the Sun stayed hot thanks to gravitational contraction. What was the major drawback of this idea? It is physically impossible to generate heat simply by making a star shrink in size. It predicted that the Sun would shrink noticeably as we watched it, and the Sun appears to be stable in size. It predicted that the Sun could last only about 25 million years, which is far less than the age of Earth. It predicted that Earth would also shrink, which would make it impossible to have stable geology on our planet. |
It predicted that the Sun could last only about 25 million years, which is far less than the age of Earth. |
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What do we mean when we say that the Sun is in gravitational equilibrium? The hydrogen gas in the Sun is balanced so that it never rises upward or falls downward. The Sun maintains a steady temperature. There is a balance within the Sun between the outward push of pressure and the inward pull of gravity. The SUn always has the same amount of mass, creating the same gravitational force. This is another way of stating that the Sun generates energy by nuclear fusion. |
There is a balance within the Sun between the outward push of pressure and the inward pull of gravity. |
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What is the approximate composition of the Sun? 50 percent hydrogen, 25 percent helium, 25 percent other elements 100 percent hydrogen and helium 70 percent hydrogen, 28 percent helium, 2 percent other elements 70 percent helium, 28 percent hydrogen, 2 percent other elements 98 percent hydrogen, 2 percent helium and other elements |
70 percent hydrogen, 28 percent helium, 2 percent other elements |
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What are the appropriate units for the Sun's luminosity? kilograms watts meters joules Newtons |
watts |
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What is the average temperature of the surface of the Sun? 10,000 K 100 million K 100,000 K 10 million K 6,000 K |
6,000 K |
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Which is closest to the temperature of the core of the Sun? 10,000 K 100 million K 100,000 K 10 million K |
10 million K |
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From the center outward, which of the following lists the "layers" of the Sun in the correct order? core, radiation zone, convection zone, photosphere, chromosphere, corona core, convection zone, radiation zone, corona, chromosphere, photosphere core, convection zone, radiation zone, photosphere, chromosphere core, corona, radiation zone, convection zone, photosphere, chromosphere core, radiation zone, convection zone, corona, chromosphere, photosphere |
core, radiation zone, convection zone, photosphere, chromosphere, corona |
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Which layer of the Sun do we normally see? corona radiation zone convection zone photosphere chromosphere |
photosphere |
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The core of the Sun is constantly rising to the surface through convection. hotter and denser than the surface. at the same temperature but denser than the surface. at the same temperature and density as the surface. composed of iron. |
hotter and denser than the surface. |
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Why do sunspots appear dark in pictures of the Sun? They are tiny black holes, absorbing all light that hits them. They are too cold to emit any visible light. They actually are fairly bright but appear dark against the even brighter background of the surrounding Sun. They are holes in the solar surface through which we can see to deeper, darker layers of the Sun. They emit light in other wavelengths that we can't see. |
They actually are fairly bright but appear dark against the even brighter background of the surrounding Sun. |
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How does the Sun generate energy today? chemical reactions nuclear fission nuclear fusion gradually expanding in size gravitational contraction |
nuclear fusion |
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At the center of the Sun, fusion converts hydrogen into plasma. hydrogen compounds. radioactive elements like uranium and plutonium. radiation and elements like carbon and nitrogen. helium, energy, and neutrinos. |
helium, energy, and neutrinos. |
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Suppose you put two protons near each other. Because of the electromagnetic force, the two protons will remain stationary. repel each other. collide. join together to form a nucleus. attract each other. |
repel each other |
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The first step in the proton-proton chain produces an antielectron, or positron. What happens to the positron? It is rapidly converted to energy when it meets an ordinary electron, resulting in matter-antimatter annihilation. It quickly meets an ordinary electron, forming an electron-position pair that remains stable. It rapidly escapes from the Sun, traveling into space at nearly the speed of light. It slowly works its way to the Sun's surface, where it escapes into space. It joins with a nearby neutron to form a proton. |
It is rapidly converted to energy when it meets an ordinary electron, resulting in matter-antimatter annihilation. |
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The overall fusion reaction by which the Sun currently produces energy is 6 H--> 1 He + energy. 3 H--> 1 Li + energy. 4 H--> 1 He + energy. 3 He--> 1 C + energy. 4 H--> 4 He + energy. |
4 H --> 1 He + energy |
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Which statement best describes the solar neutrino problem? Solar neutrinos have been detected, but in fewer numbers than predicted by theoretical models. The term solar neutrino problem refers to the fact that neutrinos are extremely difficult to detect. Our current understanding of fusion in the Sun suggests tat all neutrinos should be destroyed before they arrive as Earth, yet neutrinos are being detected. No one understands how it can be possible for neutrinos to be produced in the Sun. Theoretical in the Sun, but no neutrinos have ever been observed to be coming from the Sun. |
Solar neutrinos have been detected, but in fewer numbers than predicted by theoretical models. |
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Why are neutrinos so difficult to detect? because they have no mass because they move at nearly the speed of light because they are so rare because they rarely interact with matter because they are so small |
because they rarely interact with matter |
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What is a possible solution to the solar neutrino problem? Not all fusion reactions create electron neutrinos. The Sun is generating energy other than by nuclear fusion. The Sun is generating much less energy than we think it is. We do not know how to detect electron neutrinos. The electron neutrinos created in the Sun change into another type of neutrino that we do not detect. |
The electron neutrinos created in the Sun change into another type of neutrino that we do not detect. |
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What happens to energy in the convection zone of the Sun? Energy is consumed in the convection zone by the creation of electrons and positrons. Energy slowly leaks outward through the diffusion of photons that repeatedly bounce off ions and electrons. Energy is produced in the convection zone by nuclear fusion. Energy is transported outward by the rising of hot plasma and the sinking of cooler plasma. |
Energy is transported outward by the rising of hot plasma and the sinking of cooler plasma. |
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Most of the energy produced in the Sun is released in the form of visible light form the photosphere. However, some energy is released from the upper layers of the solar atmosphere. Which of the following best describes where other forms of light are released? The chromosphere is the source of X rays, and the corona is the source of radio waves. The convection zone is the source of ultraviolet light, and the upper photosphere is the source of X rays. The chromosphere is the source of infrared light, and the corona is the source of ultraviolet light. The chromosphere is the source of ultraviolet light, and the corona is the source of X rays. |
The chromosphere is the source of ultraviolet light, and the corona is the source of X rays. |
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What is granulation in the Sun? lumps of denser material in the Sun elements in the Sun other than hydrogen and helium dust particles in the Sun that haven't been turned into plasma another name for the way sunspots look on the surface of the Sun the bubbling pattern on the photosphere produced by the underlying convection |
the bubbling pattern on the photosphere produced by the underlying convection |
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What processes are involved in the sunspot cycle? wave motions in the solar interior the winding of magnetic field lines due to differential rotation cvariations of the solar thermostat gravitational contraction of the Sun |
the winding of magnetic field lines due to differential rotation |
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What observations characterize solar maximum? The Sun rotates faster at the equator. The Sun emits light of longer average wavelength. We see many sunspots on the surface of the Sun. The Sun becomes much brighter. all of the above |
We see many sunspots on the surface of the Sun. |
