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Chapter 11 Homework
| Question | Answer |
|---|---|
| What do we mean when we say that the Sun is in gravitational equilibrium? | There is a balance within the Sun between the outward push of pressure and the inward pull of gravity. |
| Which of the following is the best answer to the question, "Why does the Sun shine?" | As the Sun was forming, gravitational contraction increased the Sun's temperature until the core become hot enough for nuclear fusion, which ever since has generated the heat that makes the Sun shine. |
| How does the Sun's mass compare to Earth's mass? | The Sun's mass is about 300,000 times the mass of the Earth. |
| The Sun's surface seethes and churns with a bubbling pattern. Why? | We are seeing hot gas rising and cool gas falling as a result of the convection that occurs beneath the surface. |
| According to modern science, approximately how old is the Sun? | 4 1/2 billion years |
| The Sun will exhaust its nuclear fuel in about ______. | 5 billion years |
| The source of energy that keeps the Sun shining today is _________. | nuclear fusion |
| What is the Sun’s approximate composition (by mass)? | 70% hydrogen, 28% helium, 2% other elements |
| From center outward, which of the following lists the "layers" of the Sun in the correct order? | Core, radiation zone, convection zone, photosphere, chromosphere, corona |
| The Sun's visible surface (that is, the surface we can see with our eyes) is called the _________. | photosphere |
| The Sun's average surface (photosphere) temperature is about ______. | 5,800 K |
| The dark spots in this photo (such as the one indicated by the arrow) represent what we call: | sunspots |
| Every second, the Sun converts about 600 million tons of hydrogen into 596 million tons of helium. The remaining 4 million tons of mass is _________. | converted to an amount of energy equal to 4 million tons times the speed of light squared |
| How does a natural “solar thermostat” keeps the core fusion rate steady in the Sun? | If the Sun’s core were a bit hotter, the fusion rate would increase. This would produce more energy, which would cause the core to expand slightly and cool. |
| Which of these layers of the Sun is coolest? | photosphere |
| The fundamental nuclear reaction occurring in the core of the Sun is _________. | nuclear fusion of hydrogen into helium |
| The proton-proton chain is _________. | the specific set of nuclear reactions through which the Sun fuses hydrogen into helium |
| The light radiated from the Sun's surface reaches Earth in about 8 minutes, but the energy of that light was released by fusion in the solar core about _________. | a few hundred thousand years ago |
| This photograph shows a small portion of the Sun's photosphere. What is going on in the bright regions (such as the bright region indicated by the arrow)? | Hot gas is rising up from the solar interior. |
| What happens to energy in the Sun's convection zone? | Energy is transported outward by the rising of hot plasma and sinking of cooler plasma. |
| Study this figure and its axis labels. What is this graph showing us? | The number of sunspots on the Sun tends to increase and decrease with an approximately 11-year cycle. |
Created by:
ava.h14