Question 1

Granulation, or the mottled appearance of the whole solar surface, is an indication of what physical process at work in the Sun?

Accepted Answer

Granulation on the Sun's surface is caused by the convective motion of gases in the upper portion of the Sun's interior. This process involves hot gases rising to the surface, cooling, and then sinking back down, creating a mottled appearance.

Question 2

The temperature of the Sun's photosphere is nearly

Accepted Answer

The temperature of the Sun's photosphere is approximately 5800 Kelvin (K). This is the visible surface of the Sun from which light is emitted.

Question 3

Spectral lines observed in the granules seen at the center of the Sun's disk are

Accepted Answer

Granules on the Sun's surface are the tops of convection cells where hot gas rises in the center, cools, and then descends at the edges. This motion causes spectral lines to be blueshifted (indicating motion towards us) at the center where the hot gas is rising, and redshifted (indicating motion away from us) at the edges where the gas is descending back into the Sun.

Question 4

Which of these does NOT help to explain why the photosphere is called the visible surface of the Sun?

Accepted Answer

The photosphere is called the visible surface of the Sun primarily because it is the layer from which most of the Sun's visible light is emitted, not because of an abrupt change in density.

Question 5

The Stefan-Boltzmann law indicates that the energy emitted per second per area of an emitting surface varies with the fourth power of the Kelvin temperature. Suppose the center of a granule on the Sun's photosphere is 6000 K and the edges of the cell are 100 K cooler. About how much energy is emitted each second from each unit area on the edge compared with that from the center?

Accepted Answer

The Stefan-Boltzmann law states that the energy emitted per unit area is proportional to the fourth power of the temperature (T) in Kelvin. If the center of a granule is at 6000 K, and the edges are 100 K cooler (5900 K), then the ratio of energy emitted from the edge to that from the center is (5900/6000)^4. This calculation gives a value close to 0.93, or 93%, indicating that the edges emit about 93% of the energy per unit area compared to the center.

Question 6

The photosphere of the Sun is the

Accepted Answer

The photosphere is considered the visible "surface" of the Sun, where light is emitted that we can see from Earth. It is not the middle layer of the atmosphere, the region of convecting gases below the surface, or the core where nuclear reactions occur.

Question 7

Granulation on the surface of the Sun is caused by

Accepted Answer

Granulation on the surface of the Sun is caused by convective currents carrying heat from beneath the surface. These currents rise and fall, creating a mottled appearance known as granulation.

Question 8

The approximate temperature of the visible surface of the Sun is

Accepted Answer

The visible surface of the Sun, known as the photosphere, has an approximate temperature of 5800 Kelvin.

Question 9

The centers of the granular cells on the surface of the Sun appear to be brighter than the edges of the cells because

Accepted Answer

The centers of the granular cells are hotter than the edges, causing them to appear brighter. This is due to the convective motion of hot gases rising in the centers and cooler gases descending at the edges.

Question 10

The granular appearance of the surface of the Sun is evidence of what phenomenon occurring in or on the Sun?

Accepted Answer

The granular appearance of the Sun's surface is evidence of convective motion under the solar surface. These granules are the tops of convection cells where hot plasma rises, cools, and then sinks back down, creating a pattern similar to boiling water.

Question 11

If granulation on the Sun's surface is a result of convective motion below it, with material upwelling at cell centers and returning between the cells, what is the expected temperature distribution across a granular cell?

Accepted Answer

The center of a granular cell is hotter than the edges because material rises at the center where it is hotter, and as it reaches the surface and cools, it moves outward and sinks at the edges, making the edges cooler.

Question 12

A typical granule on the surface of the Sun is

Accepted Answer

Granules on the Sun's surface are about 1000 km across and typically last for a few minutes. They are convection cells within the Sun's photosphere, where hot plasma rises, cools, and then sinks back down.

Question 13

What is the explanation for the bright cells of photospheric gases that make up the cellular granulation pattern seen on the visible surface of the Sun?

Accepted Answer

The bright cells of photospheric gases, known as granules, are visible due to the convection currents that transport heat from the interior of the Sun to its surface. These granules are the tops of convective cells or blobs of hot gas that have risen from the Sun's convective zone, cooling and descending as they release their heat. This process creates the granulation pattern observed on the Sun's surface.

Question 14

The gas motions within granules on the solar surface are

Accepted Answer

Granules on the solar surface are areas of convective motion where hot gas rises in the bright cell centers and cooler gas descends around the darker edges. This process is part of the Sun's convective zone, where energy is transported outward by the movement of the gas.

Question 15

The thickness of the photosphere, or the visible "surface" of the Sun, is

Accepted Answer

The photosphere of the Sun is approximately 400 km thick, which is the layer from which most of the Sun's visible light is emitted.

Question 16

How does the average density of the Sun compare with that of the planet Jupiter?

Accepted Answer

The average density of the Sun is similar to that of Jupiter. Despite the Sun's much larger mass, its immense volume results in an average density that is comparable to Jupiter's. Both are primarily composed of hydrogen and helium, contributing to their similar densities.

Question 17

If the temperature of the solar surface is 5800 K and Wien's law for the peak wavelength of the spectrum of the Sun, assumed to be a blackbody, is given by $\lambda$_max T = 2.9*10⁶, with T in Kelvins and $\lambda$ in nanometers (nm), what is the expected peak wavelength of light from the Sun?

Accepted Answer

Wien's law states that the peak wavelength of the spectrum of a blackbody is inversely proportional to its temperature. The higher the temperature, the shorter the peak wavelength. The temperature of the solar surface is 5800 K, so the peak wavelength of light from the Sun is expected to be around 500 nm, which is in the visible light range.

Question 18

The granulation observed on the photosphere of the Sun appears to be the result of

Accepted Answer

Granulation on the Sun's photosphere is caused by convection currents beneath the surface. These currents carry heat from the interior of the Sun to its surface, creating a pattern of bright (hot) and dark (cooler) regions that appear granulated.

Question 19

What term is given to the visible "surface" of the Sun?

Accepted Answer

The photosphere is considered the visible "surface" of the Sun, as it is the layer from which most of the Sun's visible light is emitted.

Question 20

What is the Sun's photosphere?

Accepted Answer

The Sun's photosphere is considered the lowest layer of the Sun's atmosphere, where light is emitted that we can see from Earth. It's essentially the "surface" of the Sun as viewed in visible light.

Quiz 11: The Sun: Our Extraordinary Star

Granulation, or the mottled appearance of the whole solar surface, is an indication of what physical process at work in the Sun?

The temperature of the Sun's photosphere is nearly

Spectral lines observed in the granules seen at the center of the Sun's disk are

Which of these does NOT help to explain why the photosphere is called the visible surface of the Sun?

The photosphere of the Sun is the

Granulation on the surface of the Sun is caused by

The approximate temperature of the visible surface of the Sun is

The centers of the granular cells on the surface of the Sun appear to be brighter than the edges of the cells because

The granular appearance of the surface of the Sun is evidence of what phenomenon occurring in or on the Sun?

If granulation on the Sun's surface is a result of convective motion below it, with material upwelling at cell centers and returning between the cells, what is the expected temperature distribution across a granular cell?

A typical granule on the surface of the Sun is

What is the explanation for the bright cells of photospheric gases that make up the cellular granulation pattern seen on the visible surface of the Sun?

The gas motions within granules on the solar surface are

The thickness of the photosphere, or the visible "surface" of the Sun, is

How does the average density of the Sun compare with that of the planet Jupiter?

If the temperature of the solar surface is 5800 K and Wien's law for the peak wavelength of the spectrum of the Sun, assumed to be a blackbody, is given by $\lambda$ _max T = 2.9*10⁶, with T in Kelvins and $\lambda$ in nanometers (nm) , what is the expected peak wavelength of light from the Sun?

The granulation observed on the photosphere of the Sun appears to be the result of

What term is given to the visible "surface" of the Sun?

What is the Sun's photosphere?

Quiz 11: The Sun: Our Extraordinary Star

Granulation, or the mottled appearance of the whole solar surface, is an indication of what physical process at work in the Sun?

The temperature of the Sun's photosphere is nearly

Spectral lines observed in the granules seen at the center of the Sun's disk are

Which of these does NOT help to explain why the photosphere is called the visible surface of the Sun?

The photosphere of the Sun is the

Granulation on the surface of the Sun is caused by

The approximate temperature of the visible surface of the Sun is

The centers of the granular cells on the surface of the Sun appear to be brighter than the edges of the cells because

The granular appearance of the surface of the Sun is evidence of what phenomenon occurring in or on the Sun?

If granulation on the Sun's surface is a result of convective motion below it, with material upwelling at cell centers and returning between the cells, what is the expected temperature distribution across a granular cell?

A typical granule on the surface of the Sun is

What is the explanation for the bright cells of photospheric gases that make up the cellular granulation pattern seen on the visible surface of the Sun?

The gas motions within granules on the solar surface are

The thickness of the photosphere, or the visible "surface" of the Sun, is

How does the average density of the Sun compare with that of the planet Jupiter?

If the temperature of the solar surface is 5800 K and Wien's law for the peak wavelength of the spectrum of the Sun, assumed to be a blackbody, is given by λ\lambdaλ max T = 2.9*106, with T in Kelvins and λ\lambdaλ in nanometers (nm) , what is the expected peak wavelength of light from the Sun?

The granulation observed on the photosphere of the Sun appears to be the result of

What term is given to the visible "surface" of the Sun?

What is the Sun's photosphere?

If the temperature of the solar surface is 5800 K and Wien's law for the peak wavelength of the spectrum of the Sun, assumed to be a blackbody, is given by $\lambda$ _max T = 2.9*10⁶, with T in Kelvins and $\lambda$ in nanometers (nm) , what is the expected peak wavelength of light from the Sun?