1. The SunThe Sun may seem special to us, but compared to the 100
billion or more other stars in our galaxy, it is not particularly
unique. Although stars vary considerably in size, temperature,
brightness, and density, the Sun is about average in terms of these
characteristics. The Sun’s general regions are shown in Figure 2-2-1.The
InteriorThe innermost portion of the Sun consists of its core, the
radiation zone, and the convection zone. The core is characterized by
extremely high temperatures (about 15 million °C, or 27 million °F) and
high densities that lead to the energy-generating process of nuclear
fusion. In this reaction, hydrogen atoms combine under tremendous heat
and pressure to form a smaller number of heavier helium atoms. A certain
amount of mass is lost in the process, and radiant energyis
released—the same energy that works its way to the solar surface,
travels through space, and ultimately warms Earth. The amount of this
energy is staggering. Try to imagine the explosion of 100 billion
hydrogen bombs—that is equivalent to the amount of energy released in
the core every second!Energy initially travels outward from the core as
electromagnetic energy through the radiation zone and into the base of
the convection zone, where upwelling of the solar gases transfers the
energyto the relatively thin solar surface.The PhotosphereThe layer of
the Sun that radiates most of the energy away from the Sun is called the
photosphere. It is the layer of the Sun we actually see as the solar
disk. Although radiation travels from the photosphere to Earth in only
about 8 minutes, the transfer of radiant energy within the Sun is
incredibly slow. In fact, it takes about a million years for the energy
unleashed in the core to travel to the base of the photosphere; thus,
the energy reaching Earth is ancient.The photosphere is marked by a
number of features of varying sizes and lifetimes. Granules are the
ever-present tops of convection cells that transport energy from the
base of the photosphere to its surface. These features, analogous to
bubbles in a pot of boiling water, are about 1000 km (600 mi) in
diameter with life spans on the order of 5 to 10 minutes. At any given
time, there are millions of these on the surface of the
photosphere.Sunspots (each lasting a few weeks or months) are dark
regions on the photosphere with diameters of about 10,000 km (6000 mi)
and temperatures about 1500 °C cooler than the surrounding surface. They
form in response to locally strong magnetic fields, a thousand times
more intense than those of the surrounding photosphere, which block the
upwelling of heat from below.Sunspots remain fixed in place and appear
to move because of the rotation of the Sun (which takes about 24 days
and 16 hours to complete one turn of its axis). The number of sunspots
tends to peak every 11 years (Figure 2-2-2). Although the cycle is
usually well defined, long episodes of minimal or unusually high sunspot
activity have appeared during historic times. Figure 2-2-2 shows a long
period of reduced sunspot activity during the 17th cenury. Associated
with these changes in sunspot number are very small changes in solar
radiation on the order of about 0.1 percent. In light of such small
radiation changes, it is not surprising that no definitive connections
have been established between sunspots and climate.Perhaps the most
spectacular of solar disturbances are flares, intensely hot flashes
(perhaps 100 million °C) across the photosphere surface due to magnetic
instabilities. Temperatures within flares can achieve a staggering
100,000,000 K. They exist for only a matter of minutes but they emit a
huge amount of energy, particularly in the form of X-ray and ultraviolet
radiation.The ChromosphereThe chromosphere is a very thin layer about
2,000 km (1200 mi) in thickness. The chromosphere has an extremely low
density and is almost always invisible from Earth. However, the
chromosphere can be evident during total solar eclipses.FIGURE 2-2-1
Layers of the Sun. Energy is produced in the core of the Sun by nuclear
fusion. Within the Sun the energy is radiated to the base of the
convection zone, where mixing transfers the energy upward to the base of
the photosphere (the layer of the Sun visible from Earth)....FIGURE
2-2-2 Sunspots. With peak occurrences normally observed about every 11
years, sunspots appear with some regularity. As seen in the smoothed
curve (black), there are also long-term changes in average sunspot
number. Much of the 17th century, for example, was marked by minimal
sunspot activity. This period is known as the Maunder minimum....What
are the three layers of the Sun? Get solution
2. The SunThe Sun may seem special to us, but compared to the 100 billion or more other stars in our galaxy, it is not particularly unique. Although stars vary considerably in size, temperature, brightness, and density, the Sun is about average in terms of these characteristics. The Sun’s general regions are shown in Figure 2-2-1.The InteriorThe innermost portion of the Sun consists of its core, the radiation zone, and the convection zone. The core is characterized by extremely high temperatures (about 15 million °C, or 27 million °F) and high densities that lead to the energy-generating process of nuclear fusion. In this reaction, hydrogen atoms combine under tremendous heat and pressure to form a smaller number of heavier helium atoms. A certain amount of mass is lost in the process, and radiant energyis released—the same energy that works its way to the solar surface, travels through space, and ultimately warms Earth. The amount of this energy is staggering. Try to imagine the explosion of 100 billion hydrogen bombs—that is equivalent to the amount of energy released in the core every second!Energy initially travels outward from the core as electromagnetic energy through the radiation zone and into the base of the convection zone, where upwelling of the solar gases transfers the energyto the relatively thin solar surface.The PhotosphereThe layer of the Sun that radiates most of the energy away from the Sun is called the photosphere. It is the layer of the Sun we actually see as the solar disk. Although radiation travels from the photosphere to Earth in only about 8 minutes, the transfer of radiant energy within the Sun is incredibly slow. In fact, it takes about a million years for the energy unleashed in the core to travel to the base of the photosphere; thus, the energy reaching Earth is ancient.The photosphere is marked by a number of features of varying sizes and lifetimes. Granules are the ever-present tops of convection cells that transport energy from the base of the photosphere to its surface. These features, analogous to bubbles in a pot of boiling water, are about 1000 km (600 mi) in diameter with life spans on the order of 5 to 10 minutes. At any given time, there are millions of these on the surface of the photosphere.Sunspots (each lasting a few weeks or months) are dark regions on the photosphere with diameters of about 10,000 km (6000 mi) and temperatures about 1500 °C cooler than the surrounding surface. They form in response to locally strong magnetic fields, a thousand times more intense than those of the surrounding photosphere, which block the upwelling of heat from below.Sunspots remain fixed in place and appear to move because of the rotation of the Sun (which takes about 24 days and 16 hours to complete one turn of its axis). The number of sunspots tends to peak every 11 years (Figure 2-2-2). Although the cycle is usually well defined, long episodes of minimal or unusually high sunspot activity have appeared during historic times. Figure 2-2-2 shows a long period of reduced sunspot activity during the 17th cenury. Associated with these changes in sunspot number are very small changes in solar radiation on the order of about 0.1 percent. In light of such small radiation changes, it is not surprising that no definitive connections have been established between sunspots and climate.Perhaps the most spectacular of solar disturbances are flares, intensely hot flashes (perhaps 100 million °C) across the photosphere surface due to magnetic instabilities. Temperatures within flares can achieve a staggering 100,000,000 K. They exist for only a matter of minutes but they emit a huge amount of energy, particularly in the form of X-ray and ultraviolet radiation.The ChromosphereThe chromosphere is a very thin layer about 2,000 km (1200 mi) in thickness. The chromosphere has an extremely low density and is almost always invisible from Earth. However, the chromosphere can be evident during total solar eclipses.FIGURE 2-2-1 Layers of the Sun. Energy is produced in the core of the Sun by nuclear fusion. Within the Sun the energy is radiated to the base of the convection zone, where mixing transfers the energy upward to the base of the photosphere (the layer of the Sun visible from Earth)....FIGURE 2-2-2 Sunspots. With peak occurrences normally observed about every 11 years, sunspots appear with some regularity. As seen in the smoothed curve (black), there are also long-term changes in average sunspot number. Much of the 17th century, for example, was marked by minimal sunspot activity. This period is known as the Maunder minimum....Describe the types of features that episodically appear on the photosphere. Get solution
2. The SunThe Sun may seem special to us, but compared to the 100 billion or more other stars in our galaxy, it is not particularly unique. Although stars vary considerably in size, temperature, brightness, and density, the Sun is about average in terms of these characteristics. The Sun’s general regions are shown in Figure 2-2-1.The InteriorThe innermost portion of the Sun consists of its core, the radiation zone, and the convection zone. The core is characterized by extremely high temperatures (about 15 million °C, or 27 million °F) and high densities that lead to the energy-generating process of nuclear fusion. In this reaction, hydrogen atoms combine under tremendous heat and pressure to form a smaller number of heavier helium atoms. A certain amount of mass is lost in the process, and radiant energyis released—the same energy that works its way to the solar surface, travels through space, and ultimately warms Earth. The amount of this energy is staggering. Try to imagine the explosion of 100 billion hydrogen bombs—that is equivalent to the amount of energy released in the core every second!Energy initially travels outward from the core as electromagnetic energy through the radiation zone and into the base of the convection zone, where upwelling of the solar gases transfers the energyto the relatively thin solar surface.The PhotosphereThe layer of the Sun that radiates most of the energy away from the Sun is called the photosphere. It is the layer of the Sun we actually see as the solar disk. Although radiation travels from the photosphere to Earth in only about 8 minutes, the transfer of radiant energy within the Sun is incredibly slow. In fact, it takes about a million years for the energy unleashed in the core to travel to the base of the photosphere; thus, the energy reaching Earth is ancient.The photosphere is marked by a number of features of varying sizes and lifetimes. Granules are the ever-present tops of convection cells that transport energy from the base of the photosphere to its surface. These features, analogous to bubbles in a pot of boiling water, are about 1000 km (600 mi) in diameter with life spans on the order of 5 to 10 minutes. At any given time, there are millions of these on the surface of the photosphere.Sunspots (each lasting a few weeks or months) are dark regions on the photosphere with diameters of about 10,000 km (6000 mi) and temperatures about 1500 °C cooler than the surrounding surface. They form in response to locally strong magnetic fields, a thousand times more intense than those of the surrounding photosphere, which block the upwelling of heat from below.Sunspots remain fixed in place and appear to move because of the rotation of the Sun (which takes about 24 days and 16 hours to complete one turn of its axis). The number of sunspots tends to peak every 11 years (Figure 2-2-2). Although the cycle is usually well defined, long episodes of minimal or unusually high sunspot activity have appeared during historic times. Figure 2-2-2 shows a long period of reduced sunspot activity during the 17th cenury. Associated with these changes in sunspot number are very small changes in solar radiation on the order of about 0.1 percent. In light of such small radiation changes, it is not surprising that no definitive connections have been established between sunspots and climate.Perhaps the most spectacular of solar disturbances are flares, intensely hot flashes (perhaps 100 million °C) across the photosphere surface due to magnetic instabilities. Temperatures within flares can achieve a staggering 100,000,000 K. They exist for only a matter of minutes but they emit a huge amount of energy, particularly in the form of X-ray and ultraviolet radiation.The ChromosphereThe chromosphere is a very thin layer about 2,000 km (1200 mi) in thickness. The chromosphere has an extremely low density and is almost always invisible from Earth. However, the chromosphere can be evident during total solar eclipses.FIGURE 2-2-1 Layers of the Sun. Energy is produced in the core of the Sun by nuclear fusion. Within the Sun the energy is radiated to the base of the convection zone, where mixing transfers the energy upward to the base of the photosphere (the layer of the Sun visible from Earth)....FIGURE 2-2-2 Sunspots. With peak occurrences normally observed about every 11 years, sunspots appear with some regularity. As seen in the smoothed curve (black), there are also long-term changes in average sunspot number. Much of the 17th century, for example, was marked by minimal sunspot activity. This period is known as the Maunder minimum....Describe the types of features that episodically appear on the photosphere. Get solution
