Chapter 14 home work 12 The sun Flashcards
According to modern science, approximately how old is the Sun?
10,000 years
400 million years.
25 million years
4 1/2 billion years
4 1/2 billion years
The Sun will exhaust its nuclear fuel in about ______.
5 billion years
50 billion years
5 million years
5000 AD
5 billion years
What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?
the nuclear force and the electromagnetic force
the nuclear force and the gravitational force
gravitational force and outward pressure
gravitational force and surface tension
gravitational force and outward pressure
The source of energy that keeps the Sun shining today is _________.
chemical reactions
nuclear fusion
nuclear fission
gravitational contraction
nuclear fusion
What is the Sun made of (by mass)?
50% hydrogen, 25% helium, 25% other elements
100% hydrogen and helium
70% hydrogen, 28% helium, 2% other elements
90% dark matter, 10% ordinary matter
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
Core, radiation zone, convection zone, corona, chromosphere, photosphere
Core, convection zone, radiation zone, corona, chromosphere, photosphere
Core, corona, radiation zone, convection zone, photosphere, chromosphere
Core, radiation zone, convection zone, photosphere, chromosphere, corona
The Sun’s surface, as we see it with our eyes, is called the _________.
chromosphere
core
corona
photosphere
photosphere
The Sun’s average surface temperature of the sun at its photosphere is about ______.
37,000 K
5,800 K
1,000 K
1,000,000 K
5,800 K
The fundamental nuclear reaction occurring in the core of the Sun is _________.
nuclear fission
nuclear fusion of hydrogen into helium
nuclear fusion of helium to carbon
radioactive decay
nuclear fusion of 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 _________.
three days ago
one hundred years ago
a few hundred thousand years ago
one thousand years ago
a few hundred thousand years ago
What happens to energy in the Sun’s convection zone?
Energy slowly leaks outward through the radiative diffusion of photons that repeatedly bounce off ions and electrons.
Energy is produced in the convection zone by nuclear fusion.
Energy is produced in the convection zone by thermal radiation.
Energy is transported outward by the rising of hot plasma and sinking of cooler plasma.
Energy is transported outward by the rising of hot plasma and sinking of cooler plasma.
What do sunspots, solar prominences, and solar flares all have in common?
They all have about the same temperature.
They all occur only in the Sun's photosphere.
They are all strongly influenced by magnetic fields on the Sun.
They are all shaped by the solar wind.
They are all strongly influenced by magnetic fields on the Sun.
Which of the following is not a characteristic of the 11-year sunspot cycle?
The Sun's entire magnetic field flip-flops with each cycle, so that the overall magnetic cycle averages 22 years.
The sunspot cycle is very steady, so that each 11-year cycle is nearly identical to every other 11-year cycle.
The likelihood of seeing solar prominences or solar flares is higher when sunspots are more common and lower when they are less common.
The number of sunspots on the Sun at any one time gradually rises and falls, with an average of 11 years between the times when sunspots are most numerous.
The sunspot cycle is very steady, so that each 11-year cycle is nearly identical to every other 11-year cycle.
How is the sunspot cycle directly relevant to us here on Earth?
The sunspot cycle is the cause of global warming.
The Sun's magnetic field, which plays a major role in the sunspot cycle, affects compass needles that we use on Earth.
Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment.
The brightening and darkening of the Sun that occurs during the sunspot cycle affects plant photosynthesis here on Earth.
The sunspot cycle strongly influences Earth's weather.
Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment.
Listed following are the different layers of the Sun. Rank these layers based on their distance from the Sun’s center, from greatest to least. Corna chromosphere' photosphere convection zone radiation zone core
Corna chromosphere' photosphere convection zone radiation zone core
Rank the layers of the Sun based on their density, from highest to lowest.
core radiation zone convection zone photosphere chromosphere cornoa
core radiation zone convection zone photosphere chromosphere cornoa
Rank the following layers of the Sun based on their temperature, from highest to lowest.
core
radiation zone
convection zone
photosphere
core
radiation zone
convection zone
photosphere
Rank the following layers of the Sun based on the pressure within them, from highest to lowest.
core
radiation zone
convection zone
photosphere
core
radiation zone
convection zone
photosphere
In which of the following layer(s) of the Sun does nuclear fusion occur?
Select all that apply.
corona radiation zone convection zone photosphere core chromosphere
core
Which of the following layers of the Sun can be seen with some type of telescope? Consider all forms of light, but do not consider neutrinos or other particles.
Select all that apply.
radiation zone convection zone chromosphere core corona photosphere
chromosphere
corona
photosphere
Following are the different layers of the Sun’s atmosphere. Rank them based on the order in which a probe would encounter them when traveling from Earth to the Sun’s surface, from first encountered to last.
corona
chromosphere
photosphere
corona
chromosphere
photosphere
Rank the layers of the Sun’s atmosphere based on their density, from highest to lowest.
photosphere
chromosphere
cornoa
photosphere
chromosphere
cornoa
Rank the layers of the Sun’s atmosphere based on their temperature, from highest to lowest.
corona
chromosphere
photosphere
corona
chromosphere
photosphere
Rank the layers of the atmosphere based on the energy of the photons that are typically emitted there, from highest to lowest.
corona
chromosphere
photosphere
corona
chromosphere
photosphere
nuclear fusion of hydrogen in helium occurs in the
core
Energy moves through the sun’s _____ by means of the rising of hot gas and falling of cooler gas.
Convection zone
Nearly all the visible light we see from the Sun is emitted from the
Photosphere
Most of the Sun’s ultraviolet light is emitted from the narrow layer called the ______ where temperature increases with altitude.
Chromosphere
We can see the Sun’s _____ most easily during total solar eclipses.
Corona
The ______ is the layer of the Sun between its core and convection zone.
radiation zone
Which of the following changes would cause the fusion rate in the Sun’s core to increase?
Check all that apply.
An increase in the core temperature An increase in the core radius A decrease in the core temperature A decrease in the core radius
An increase in the core temperature
A decrease in the core radius
Which of the following must occur for a star’s core to reach equilibrium after an initial change in fusion rate?
Check all that apply.
If the fusion rate initially decreases, then the core expands. If the fusion rate initially increases, then the core expands. If the fusion rate initially decreases, then the core contracts. If the fusion rate initially increases, then the core contracts.
If the fusion rate initially increases, then the core expands.
If the fusion rate initially decreases, then the core contracts.
What would happen if the fusion rate in the core of the Sun were increased but the core could not expand?
The Sun’s core would start to cool down and the rate of fusion would decrease. The Sun’s core would reach a new equilibrium at a lower temperature. The Sun’s core would reach a new equilibrium at a higher temperature. The Sun’s core would start to heat up and the rate of fusion would increase even more.
The Sun’s core would start to heat up and the rate of fusion would increase even more.
To understand the interplay of observations and models you must first be able to distinguish between things that we observe and things that we infer from models. Consider the following statements about the Sun. Classify each statement as an observation or as an inference based on the current, accepted model for the Sun. Observations
The photosphere is made mostly of hydrogen and helium
The photosphere emits ostly visible light.
The corona is hotter than the photosphere.
The sun emits neutrinos.
The sun generates energy by fusing hydrogen into helium in its core.
The core temperature is 10 million k
The convection zone is cooler than the radiation zone.
The composition of the photosphere is the same as that of the gas cloud that gave birth to our solar system.
The photosphere is made mostly of hydrogen and helium
The photosphere emits ostly visible light.
The corona is hotter than the photosphere.
The sun emits neutrinos.
To understand the interplay of observations and models you must first be able to distinguish between things that we observe and things that we infer from models. Consider the following statements about the Sun. Classify each statement as an observation or as an inference based on the current, accepted model for the Sun. Inferences from a Model
The photosphere is made mostly of hydrogen and helium
The photosphere emits ostly visible light.
The corona is hotter than the photosphere.
The sun emits neutrinos.
The sun generates energy by fusing hydrogen into helium in its core.
The core temperature is 10 million k
The convection zone is cooler than the radiation zone.
The composition of the photosphere is the same as that of the gas cloud that gave birth to our solar system.
The sun generates energy by fusing hydrogen into helium in its core.
The core temperature is 10 million k
The convection zone is cooler than the radiation zone.
The composition of the photosphere is the same as that of the gas cloud that gave birth to our solar system.
One statement about the Sun from Part A is “The corona is hotter than the photosphere.” Which of the following statements provides observational evidence for this claim?
The corona has a much lower gas density than the photosphere. The corona emits much less total light than the photosphere. The corona primarily emits X rays while the photosphere primarily emits visible light. The corona is higher in the Sun’s atmosphere than the photosphere.
The corona primarily emits X rays while the photosphere primarily emits visible light.
Now consider the statements in Part A that are inferred from models. A solar model is used to calculate interior conditions based on certain “known” characteristics of the Sun, such the Sun’s total mass. How do we know the Sun’s mass?
We infer the mass from a model of the Sun. We first measure the Sun's size and density, then use these measurements to calculate the Sun’s mass. We can calculate it by using the law of conservation of energy with the measured amount of light that the Sun emits. We can calculate it by applying Newton's version of Kepler's third law with Earth's orbital period (1 year) and Earth’s average distance from the Sun (1 AU).
We can calculate it by applying Newton’s version of Kepler’s third law with Earth’s orbital period (1 year) and Earth’s average distance from the Sun (1 AU).
A solar model is used to calculate the expected temperature and density at all depths within the Sun. These results are then used to calculate the expected fusion rate within the Sun. We have confidence that the model is correct because it agrees with the observed characteristics of the Sun. Which of the following observations can be used to check that we really do know the Sun’s internal fusion rate?
Select all that apply.
Measurements of the varying number of sunspots on the Sun over time Measurements of the Sun’s total energy output into space Observations of neutrinos coming from the Sun Observations of the total X-ray emission from the Sun’s corona Measurement of the Sun’s mass
Measurements of the Sun’s total energy output into space
Observations of neutrinos coming from the Sun
Listed following are events or phenomena that occur during either the part of the sunspot cycle known as solar minimum or the part known as solar maximum. Match these items to the correct part of the sunspot cycle. Solar Maximum
Occurs about 11 years after a solar maximum (on average)
Solar flares are most common
Auroras are most likely in Earth’s skies
Orbiting satellites are most at risk
Sunspots are most numerous on the Sun
Occurs about 5 to 6 years after a solar maximum ( on average)
Occurs about 11 years after a solar maximum (on average) Solar flares are most common Auroras are most likely in Earth's skies Orbiting satellites are most at risk Sunspots are most numerous on the Sun
Listed following are events or phenomena that occur during either the part of the sunspot cycle known as solar minimum or the part known as solar maximum. Match these items to the correct part of the sunspot cycle. Solar Minimum
Occurs about 11 years after a solar maximum (on average)
Solar flares are most common
Auroras are most likely in Earth’s skies
Orbiting satellites are most at risk
Sunspots are most numerous on the Sun
Occurs about 5 to 6 years after a solar maximum ( on average)
Occurs about 5 to 6 years after a solar maximum ( on average)
In the late 1800s, Kelvin and Helmholtz suggested that the Sun stayed hot due to gravitational contraction. What was the major drawback to this idea?
It predicted that Earth would also shrink in size with time, which would make it impossible to have stable geology on our planet. It is physically impossible to generate heat simply by making a star shrink in size. It predicted that the Sun could shine for about 25 million years, but geologists had already found that Earth is much older than this. It predicted that the Sun would shrink noticeably as we watched it, but the Sun appears to be stable in size.
It predicted that the Sun could shine for about 25 million years, but geologists had already found that Earth is much older than this.
What do we mean when we say that the Sun is in gravitational equilibrium?
The Sun maintains a steady temperature. The Sun always has the same amount of mass, creating the same gravitational force. The hydrogen gas in the Sun is balanced so that it never rises upward or falls downward. There is a balance within the Sun between the outward push of pressure and the inward pull of gravity
There is a balance within the Sun between the outward push of pressure and the inward pull of gravity
Which of the following correctly compares the Sun’s energy generation process to the energy generation process in human-built nuclear power plants?
Both processes involve nuclear fusion, but the Sun fuses hydrogen while nuclear power plants fuse uranium. The Sun generates energy through nuclear reactions while nuclear power plants generate energy through chemical reactions. The Sun generates energy through fission while nuclear power plants generate energy through fusion. The Sun generates energy by fusing small nuclei into larger ones, while our power plants generate energy by the fission (splitting) of large nuclei.
The Sun generates energy by fusing small nuclei into larger ones, while our power plants generate energy by the fission (splitting) of large nuclei.
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. As the Sun was forming, nuclear fusion reactions in the shrinking clouds of gas slowly became stronger and stronger, until the Sun reached its current luminosity. The Sun initially began generating energy through nuclear fusion as it formed, but today it generates energy primarily through the sunspot cycle. The Sun initially began making energy through chemical reactions. These heated the interior enough to allow gravitational contraction and nuclear fusion to occur.
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.
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 ejected into space in a solar wind ejected into space by solar flares reabsorbed as molecular hydrogen
converted to an amount of energy equal to 4 million tons times the speed of light squared
Which of the following best describes why the Sun emits most of its energy in the form of visible light?
Like all objects, the Sun emits thermal radiation with a spectrum that depends on its temperature, and the Sun's surface temperature is just right for emitting mostly visible light. Nuclear fusion in the Sun's core produces visible light photons. The visible light comes from energy level transitions as electrons in the Sun's hydrogen atoms jump between level 1 and level 2. The Sun's gas is on fire like flames from wood or coal, and these flames emit visible light.
Like all objects, the Sun emits thermal radiation with a spectrum that depends on its temperature, and the Sun’s surface temperature is just right for emitting mostly visible light.
Which of the following best explains why nuclear fusion requires bringing nuclei extremely close together?
Nuclei are attracted to each other by the electromagnetic force, but this force is only strong enough to make nuclei stick when they are very close together. Fusion can proceed only by the proton-proton chain, and therefore requires that protons come close enough together to be linked up into a chain. Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold. Nuclei have to be very hot in order to fuse, and the only way to get them hot is to bring them close together.
Nuclei normally repel because they are all positively charged and can be made to stick only when brought close enough for the strong force to take hold.
Why do sunspots appear dark in pictures of the Sun?
They actually are fairly bright, but appear dark against the even brighter background of the surrounding photosphere. They are extremely hot and emit all their radiation as X rays rather than visible light. They are too cold to emit any visible light. They are holes in the solar surface through which we can see through to deeper, darker layers of the Sun.
They actually are fairly bright, but appear dark against the even brighter background of the surrounding photosphere.
How can we best observe the Sun’s chromosphere and corona?
The chromosphere is best observed with infrared telescopes and the corona is best observed with ultraviolet telescopes. The chromosphere and corona are both best studied with visible light. The chromosphere and corona are both best studied with radio telescopes. The chromosphere is best observed with ultraviolet telescopes and the corona is best observed with X-ray telescopes.
The chromosphere is best observed with ultraviolet telescopes and the corona is best observed with X-ray telescopes.
