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Table 14.1. 492 Chapter 14 Cosmic Samples and the Origin of the Solar System Figure 14.3. Radiant of a Meteor Shower. The tracks of the meteors diverge from a point in the distance, just as long, parallel railroad tracks appear to do. (credit “tracks”: Nathan Vaughn) Major Annual Meteor Showers Shower Name Date of Max... |
rise to the particles in that swarm, called Swift-Tuttle, must originally have had at least that much mass. However, if its initial mass were comparable to the mass measured for Comet Halley, then Swift-Tuttle would have contained several hundred billion tons, suggesting that only a very small fraction of the original... |
.5. Perseid Meteor Shower. This twenty-second exposure shows a meteor during the 2015 Perseid meteor shower. (credit: NASA/Bill Ingalls) The key to observing meteor showers is not to restrict your field of view, but to lie back and scan the sky alertly. Try to select a good shower (see the list in Table 14.1) and a nig... |
Describe how most meteorites have been found Explain how primitive stone meteorites are significantly different from other types Explain how the study of meteorites informs our understanding of the age of the solar system. Any fragment of interplanetary debris that survives its fiery plunge through Earth’s atmosphere ... |
area beneath the point where the fireball burned out, we may find one or more remnants that reached the ground. Observed meteorite falls, in other words, may lead to the recovery of fallen meteorites. (A few meteorites have even hit buildings or, very rarely, people; see Making Connections: Some Striking Meteorites). ... |
ites. More than ten thousand meteorites have been recovered from the Antarctic as a result of the motion of the ice in some parts of that continent (Figure 14.7). Meteorites that fall in regions where ice accumulates are buried and then carried slowly to other areas where the ice is gradually worn away. After thousands... |
3-pound meteorite. Michelle was not sure whether to be devastated by the loss of her car or thrilled by all the media attention. In June 1994, Jose Martin and his wife were driving from Madrid, Spain, to a golfing vacation when a fist- sized meteorite crashed through the windshield of their car, bounced off the dashbo... |
“Taty2007”/Wikimedia Commons; credit c: modification of work by Juan Manuel Fluxà) Of these three types, the irons and stony-irons are the most obviously extraterrestrial because of their metallic content. Pure iron almost never occurs naturally on Earth; it is generally found here as an oxide (chemically combined wit... |
and began to form into larger bodies. The traditional classification of meteorites into irons, stones, and stony-irons is easy to use because it is obvious from inspection which category a meteorite falls into (although it may be much more difficult to distinguish a meteoritic stone from a terrestrial rock). More scie... |
, Canada, in 2000. (The fragile bits of dark material from the Tagish Lake meteorite were readily visible against the white snow, although at first they were mistaken for wolf droppings.) The Murchison meteorite (Figure 14.10) is known for the variety of organic chemicals it has yielded. Most of the carbon compounds in... |
. The planets, moons, and the Sun, of course, also are the products of the formation process, although the material in them has undergone a wide range of changes. We are now ready to put together the information from all these objects to discuss what is known about the origin of the solar system. Observational Constrai... |
move outward. The inner parts of the system are generally missing those materials that could not condense (form a solid) at the high temperatures found near the Sun. However, there are (again) important exceptions to the general pattern. For example, it is difficult to explain the presence of water on Earth and Mars i... |
In the same way, near the poles of the nebula, where orbits were slow, the nebular material fell directly into the center. Faster moving material, on the other hand, collapsed into a flat disk revolving around the central object (Figure 14.11). The existence of this disk-shaped rotating nebula explains the primary mot... |
now found abundantly among the asteroids. However, in the inner parts of the disk, the temperature never dropped low enough for such materials as ice or carbonaceous organic compounds to condense, so they were lacking on the innermost planets. Figure 14.12. Chemical Condensation Sequence in the Solar Nebula. The scale... |
the nebula in our example be when it had shrunk to the size of Jupiter’s orbit? Answer: The period of the rotating nebula is inversely proportional to D2. As we have just seen, 2 = ⎞ ⎠ ⎛ ⎝ Dfina Dinitial Pfina Pinitial years) is given by Pfina = 0.01Dfina The period is then 1.08 years. 2. Initially, we have Pinitial =... |
more of the heavier elements and compounds behind. Formation of the Giant Planets In the outer solar system, where the available raw materials included ices as well as rocks, the protoplanets grew to be much larger, with masses ten times greater than Earth. These protoplanets of the outer solar system were so large th... |
esimals and other debris that did not initially accumulate to form the planets. What was their fate? The comets visible to us today are merely the tip of the cosmic iceberg (if you’ll pardon the pun). Most comets are believed to be in the Oort cloud, far from the region of the planets. Additional comets and icy dwarf p... |
of the planets and asteroids, however, suggest that there were more violent events soon afterward, perhaps involving substantial changes in the orbits of Jupiter and Saturn. These two giant planets control, through their gravity, the distribution of asteroids. Working backward from our present solar system, it appears... |
nearest of these circumstellar disks in regions of space where stars are being born today, such as the Orion Nebula (Figure 14.14) or the Taurus star-forming region. Figure 14.14. Protoplanetary Disk in the Orion Nebula. The Hubble Space Telescope imaged this protoplanetary disk in the Orion Nebula, a region of active... |
: modification of work by ALMA (ESO/NAOJ/NRAO); credit b: modification of work by NASA/ESA and A. Feild (STScI)) Our figure shows HL Tau, a one-million-year-old “newborn” star in the Taurus star-forming region. The star is embedded in a shroud of dust and gas that obscures our visible-light view of a circumstellar disk... |
This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 14 Cosmic Samples and the Origin of the Solar System 509 the star to wobble, changing its radial velocity by a small but detectable amount. The distance of the star does not matter, as long as it is bright enough for us to take ver... |
more massive than or larger in size than Earth. It is not that Earth analogs do not exist. Rather, the shortage of small rocky planets is an observational bias: smaller planets are more difficult to detect. Analyses of the data to correct for such biases or selection effects indicate that small planets (like the terre... |
enabled the detection of lower mass planets as time went on, and now even smaller worlds are being found. (Note that this tally ends in 2014.) We also know that many exoplanets are in multiplanet systems. This is one characteristic that our solar system shares with exosystems. Looking back at Figure 14.15 and seeing h... |
expected for planets that form in a disk. This discovery provides further support for the scattering 512 Chapter 14 Cosmic Samples and the Origin of the Solar System of planets when they interact gravitationally. When planets change each other’s motions, their orbits could become much more eccentric than the ones with... |
ordial heat left over from the formation of a planet or from the decay of radioactive elements in the interior. The larger the planet or moon, the more likely it is to retain its internal heat and the more slowly it cools—this is the “baked potato effect” mentioned in Other Worlds: An Introduction to the Solar System. ... |
surface appears to be no more than 500 million years old. We did see that the surface of our sister planet is being modified by a kind of “blob tectonics”—where hot material from below puckers and bursts through the surface, leading to coronae, pancake volcanoes, and other such features. A better understanding of the ... |
its terrestrial counterparts is that the crustal plates on Earth never stop moving long enough to let a really large volcano grow. Instead, the moving plate creates a long row of volcanoes like the Hawaiian Islands. On Mars (and perhaps Venus) the crust remains stationary with respect to the underlying hot spot, and s... |
we see in photographs of asteroids, such as Figure 14.21). Figure 14.21. Irregular Asteroid. Small objects such as asteroid Ida (shown here in multiple views taken by the Galileo spacecraft camera as it flew past) are generally irregular or elongated; they do not have strong enough gravity to pull them into a spherica... |
its surface, Earth finds itself with a great deficiency of CO2, with nitrogen as the most abundant gas, and the only planetary atmosphere that contains free oxygen. In the outer solar system, Titan is the only moon with a substantial atmosphere. This object must have contained sufficient volatiles—such as ammonia, met... |
was the complex surface of Pluto revealed by New Horizons. The study of exoplanetary systems provides a new perspective, teaching us that there is much more variety among planetary systems than scientists had imagined a few decades ago. The exploration of the solar system is one of the greatest human adventures, and, ... |
(carbon- rich) molecules. 14.3 Formation of the Solar System A viable theory of solar system formation must take into account motion constraints, chemical constraints, and age constraints. Meteorites, comets, and asteroids are survivors of the solar nebula out of which the solar system formed. This nebula was the resu... |
solid worlds, mountains can result from impacts, volcanism, or uplift. Whatever their origin, higher mountains can be supported on smaller planets that have less surface gravity. The atmospheres of the terrestrial planets may have acquired volatile materials from comet impacts. The Moon and Mercury lost their atmosphe... |
planets. Young, E. “Cloudy with a Chance of Stars.” Scientific American (February 2010): 34. On how clouds of interstellar matter turn into star systems. Websites Meteors and Meteorites American Meteor Society: http://www.amsmeteors.org/. For serious observers. British and Irish Meteorite Society: http://www.bimsociet... |
news piece about a martian meteorite: https://www.youtube.com/watch?v=1EMR2r53f2s (2:54). What Is a Meteor Shower (and How to Watch Them): https://www.youtube.com/watch?v=xNmgvlwInCA. Top tips for watching meteor showers from the At-Bristol Science Center (3:18). Evolution of the Solar System and Protoplanetary Disks ... |
the harder (more expensive) it is to launch. What would you include in your recommendations? D. Discuss what you would do if you suddenly found that a small meteorite had crashed in or near your home. Whom would you call first, second, third? What would you do with the sample? (And would any damage to your home be cov... |
Why do the giant planets and their moons have compositions different from those of the terrestrial planets? 7. How do the planets discovered so far around other stars differ from those in our own solar system? List at least two ways. 8. Explain the role of impacts in planetary evolution, including both giant impacts a... |
We think the irons are from the cores, the stony-irons are from the interfaces between mantles and cores, and the stones are from the mantles of their differentiated parent bodies. If these parent bodies were like Earth, what fraction of the meteorites would you expect to consist of irons, stony-irons, and stones? Is ... |
ways that the Sun affects Earth. By studying the Sun, we also learn much that helps us understand stars in general. The Sun is, in astronomical terms, a rather ordinary star—not unusually hot or cold, old or young, large or small. Indeed, we are lucky that the Sun is typical. Just as studies of Earth help us understan... |
/col11992/1.8 Chapter 15 The Sun: A Garden-Variety Star 525 Characteristics of the Sun Characteristic How Found Value Mean distance Radar reflection from planets 1 AU (149,597,892 km) Maximum distance from Earth Minimum distance from Earth Mass Orbit of Earth 1.521 × 108 km 1.471 × 108 km 333,400 Earth masses (1.99 × 1... |
stars in general. The Abundance of Elements in the Sun Element Percentage by Number of Atoms Percentage By Mass Hydrogen Helium Carbon 92.0 7.8 0.02 Nitrogen 0.008 Oxygen Neon Magnesium Silicon Sulfur Iron Table 15.2 0.06 0.01 0.003 0.004 0.002 0.003 73.4 25.0 0.20 0.09 0.80 0.16 0.06 0.09 0.05 0.14 The fact that our ... |
a liquid or a solid. In fact, the Sun is so hot that many of the atoms in it are ionized, that is, stripped of one or more of their electrons. This removal of electrons from their atoms means that there is a large quantity of free electrons and positively charged ions in the Sun, making it an electrically charged envi... |
part of the Sun. Above the core is a region known as the radiative zone—named for the primary mode of transporting energy across it. This region starts at about 25% of the distance to the solar surface and extends up to about 70% of the way to the surface. The light generated in the core is transported through the rad... |
surface. Outside the Sun, we can observe only those photons that are emitted into the solar photosphere, where the density of atoms is sufficiently low and the photons can finally escape from the Sun without colliding with another atom or ion. This OpenStax book is available for free at http://cnx.org/content/col11992... |
layer compared to the air in the room where you are reading this text. At a typical point in the photosphere, the pressure is less than 10% of Earth’s pressure at sea level, and the density is about one ten-thousandth of Earth’s atmospheric density at sea level. Observations with telescopes show that the photosphere h... |
15.7). Because they are transparent to most visible radiation and emit only a small amount of light, these outer layers are difficult to observe. The region of the Sun’s atmosphere that lies immediately above the photosphere is called the chromosphere. Until this century, the chromosphere was visible only when the pho... |
situations we are familiar with, temperatures fall as one moves away from the source of heat, and the chromosphere is farther from the center of the Sun than the photosphere is. The Transition Region The increase in temperature does not stop with the chromosphere. Above it is a region in the solar atmosphere where the... |
shells, each one with a different temperature. For a long time, astronomers did indeed think of the Sun this way. However, we now know that while this idea of layers—photosphere, chromosphere, transition region, corona—describes the big picture fairly well, the Sun’s atmosphere is really more complicated, with hot and... |
and 1019 molecules per cubic centimeter at sea level in Earth’s atmosphere. The corona thins out very rapidly at greater heights, where it corresponds to a high vacuum by Earth laboratory standards. The corona extends so far into space—far past Earth—that here on our planet, we are technically living in the Sun’s atmo... |
from the solar wind by our atmosphere and Earth’s magnetic field (see Earth as a Planet). However, the magnetic field lines come into Earth at the north and south magnetic poles. Here, charged particles accelerated by the solar wind can follow the field down into our atmosphere. As the particles strike molecules of ai... |
�s intensity. (We emphasize what your parents have surely told you: looking at the Sun for even a brief time can cause permanent eye damage. This is the one area of astronomy where we don’t encourage you to do your own observing without getting careful instructions or filters from your instructor.) Figure 15.13. Sunspo... |
like Earth does. Modern observations show that the speed of rotation of the Sun varies according to latitude, that is, it’s different as you go north or south of the Sun’s equator. The rotation period is about 25 days at the equator, 28 days at latitude 40°, and 36 days at latitude 80°. We call this behavior different... |
’s Goddard Space Flight Center that explains the sunspot cycle. Magnetism and the Solar Cycle Now that we have discussed the Sun’s activity cycle, you might be asking, “Why does the Sun change in such a regular way?” Astronomers now understand that it is the Sun’s changing magnetic field that drives solar activity. The... |
cycle, however, the polarity of the leading spots is reversed in each hemisphere. For example, if during one cycle, the leading spots in the Northern Hemisphere all had the polarity of a north- seeking pole, then the leading spots in the Southern Hemisphere would have the polarity of a south-seeking pole. During the n... |
is a machine that converts kinetic energy (i.e., the energy of motion) into electricity. On Earth, dynamos are found in power plants where, for example, the energy from wind or flowing water is used to cause turbines to rotate. In the Sun, the source of kinetic energy is the churning of turbulent layers of ionized gas... |
most of the heat from inside the Sun to the surface by means of convection, and strong magnetic fields inhibit this convection, the surface of the Sun is allowed to cool. As a result, these regions are seen as darker, cooler sunspots. Beyond this general picture, researchers are still trying to determine why the magne... |
only the light of the spectral line produced by singly ionized calcium. The bright cloud-like regions are the plages. (credit: modification of work by NASA) Moving higher into the Sun’s atmosphere, we come to the spectacular phenomena called prominences (Figure 15.19), which usually originate near sunspots. Eclipse ob... |
. Figure 15.20. Solar Flare. The bright white area seen on the right side of the Sun in this image from the Solar Dynamics Observer spacecraft is a solar flare that was observed on June 25, 2015. (credit: NASA/SDO) This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 15 The Sun: A Gar... |
See a coronal mass ejection (https://openstax.org/l/30CorMaEj) recorded by the Solar Dynamics Observatory. Active Regions To bring the discussion of the last two sections together, astronomers now realize that sunspots, flares, and bright regions in the chromosphere and corona tend to occur together on the Sun in time... |
Stax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 15 The Sun: A Garden-Variety Star 545 Explain what space weather is and how it affects Earth In the previous sections, we have seen that some of the particles coming off the Sun—either steadily as in the solar wind or in great bursts like CM... |
to scientific speculation that a connection existed between solar activity and impacts on Earth—this was the beginning of our understanding of what today we call space weather Watch NASA scientists answer some questions (https://openstax.org/l/30SpcWeath) about space weather, and discuss (https://openstax.org/l/30SpcW... |
as photographed in 2010 by the departing crew of the Space Shuttle Atlantis. (credit: NASA) Solar Storm Damage on Earth When a CME reaches Earth, it distorts Earth’s magnetic field. Since a changing magnetic field induces electrical current, the CME accelerates electrons, sometimes to very high speeds. These “killer e... |
Power networks could be run at less than their full capacity so that they could absorb the effects of power surges. Communications networks could be prepared for malfunctions and have backup plans in place. Spacewalks could be timed to avoid major solar outbursts. Scientists are now trying to find ways to predict wher... |
Earth and how big they are. Models are being developed that will then allow scientists to use early information about the CME to predict its likely impact on Earth. The hope is that by the time of the next maximum, solar weather forecasting will have some of the predictive capability that meteorologists have achieved ... |
1715, the number of sunspots, even at sunspot maximum, was much lower than it is now. This interval of significantly low sunspot numbers was first noted by Gustav Spӧrer in 1887 and then by E. W. Maunder in 1890; it is now called the Maunder Minimum. The variation in the number of sunspots over the past three centurie... |
northeastern coasts of North America, including Newfoundland, between about 1000 and 1350. (The ships of the time did not allow the Norse explorers to travel all the way to North America directly, but only from Greenland, which served as a station for further exploration.) Most of Greenland is covered by ice, and the ... |
of the stratosphere near Earth’s poles. This, in turn, could change the circulation patterns of winds aloft and, hence, the tracks of storms. There is some recent evidence that variations in regional rainfall correlate better with solar activity than does the global temperature of Earth. But, as you can see, the relat... |
above the surface of the Sun and extends into the corona solar flare a sudden and temporary outburst of electromagnetic radiation from an extended region of the Sun’s surface solar wind a flow of hot, charged particles leaving the Sun sunspot large, dark features seen on the surface of the Sun caused by increased magn... |
leading sports in the Southern Hemisphere have the opposite polarity. In the subsequent 11-year cycle, the polarity reverses. For this reason, the magnetic activity cycle of the Sun is understood to last for 22 years. This activity cycle is connected with the behavior of the Sun’s magnetic field, but the exact mechani... |
Sun.” Sky & Telescope (February 2001): 34; (March 2001): 34. Excellent reviews of recent results about the solar atmosphere. Wadhwa, M. “Order from Chaos: Genesis Samples the Solar Wind.” Astronomy (October 2013): 54. On a satellite that returned samples of the Sun’s wind. Websites Dr. Sten Odenwald’s “Solar Storms” s... |
. Solar Monitor Pro: http://www.solarmonitor.eu/. Videos Journey into the Sun: https://www.youtube.com/watch?v=fqKFQ7z0Nuk. 2010 KQED Quest TV Program mostly about the Solar Dynamics Observatory spacecraft, its launch and capabilities, but with good general information on how the Sun works (12:24). 554 Chapter 15 The S... |
apod.nasa.gov/apod/ap150629.html. Short video (with music) animates Solar Dynamics Observatory images of an especially large sunspot group going across the Sun’s face (1:15). What Happens on the Sun Doesn’t Stay on the Sun: https://www.youtube.com/watch?v=bg_gD2-ujCk. From the National Oceanic and Atmospheric Administr... |
your group members research online to find out what satellites are in space to help astronomers study the Sun. In addition to searching for NASA satellites, you might also check for satellites launched by the European Space Agency and the Japanese Space Agency. H. Some scientists and engineers are thinking about build... |
temperature increases. How can this be? 15. Since the rotation period of the Sun can be determined by observing the apparent motions of sunspots, a correction must be made for the orbital motion of Earth. Explain what the correction is and how it arises. Making some sketches may help answer this question. 16. Suppose ... |
is consistent with the statement that 73% of the Sun’s mass is made up of hydrogen, as found in Table 15.2. (Hint: Make the simplifying assumption, which is nearly correct, that the Sun is made up entirely of hydrogen and helium.) 24. From Doppler shifts of the spectral lines in the light coming from the east and west... |
16.1. The Sun. It takes an incredible amount of energy for the Sun to shine, as it has and will continue to do for billions of years. (credit: modification of work by Ed Dunens) Chapter Outline 16.1 Sources of Sunshine: Thermal and Gravitational Energy 16.2 Mass, Energy, and the Theory of Relativity 16.3 The Solar Int... |
, coal, gasoline, or other fuel. We know exactly how much energy the burning of these materials can produce. We can thus calculate that even if the immense mass of the Sun consisted of a burnable material like coal or wood, our star could not produce energy at its present rate for more than few thousand years. However,... |
explains why brakes can overheat when used carelessly while descending long mountain roads. In the nineteenth century, scientists thought that the source of the Sun’s heat might be the mechanical motion of meteorites falling into it. Their calculations showed, however, that in order to produce the total amount of This... |
measure of the kinetic energy (motion) of the atoms within it; hence, the temperature of this layer of the Sun increases. Collisions also excite electrons within the atoms to higher-energy orbits. When these electrons return to their normal orbits, they emit photons, which can then escape from the Sun (see Radiation a... |
ASS, ENERGY, AND THE THEORY OF RELATIVITY Learning Objectives By the end of this section, you will be able to: Explain how matter can be converted into energy Describe the particles that make up atoms Describe the nucleus of an atom Understand the nuclear forces that hold atoms together Trace the nuclear reactions in t... |
2 is just the number that Einstein showed must be used to relate mass and energy. Notice that this formula does not tell us how to convert mass into energy, just as the formula for cents does not tell us where to exchange coins for a dollar bill. The formulas merely tell us what the equivalent values are if we succeed ... |
ideas that had made him famous. Einstein was born in 1879 in Ulm, Germany. Legend has it that he did not do well in school (even in arithmetic), and thousands of students have since attempted to justify a bad grade by referring to this story. Alas, like many legends, this one is not true. Records indicate that althoug... |
This portrait of Einstein was taken in 1912. (credit: modification of work by J. F. Langhans) Elementary Particles The fundamental components of atoms are the proton, neutron, and electron (see The Structure of the Atom). Protons, neutrons, and electrons are by no means all the particles that exist. First, for each ki... |
particles with zero mass, and that like photons, they moved with the speed of light. Figure 16.4. Wolfgang Pauli in 1945. Pauli is considered the “father” of the neutrino, having conceived of it in 1933. The elusive neutrino was not detected until 1956. The reason it was so hard to find is that neutrinos interact very... |
of one of your carbon atoms. It contains six protons, which have a positive charge, and six neutrons, which are neutral. Thus, the nucleus has a net charge of six positives. If only the electrical force were acting, the protons in this and every carbon atom would find each other very repulsive and fly apart. The stron... |
to explain the energy of the Sun and the stars (Figure 16.5). This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 16 The Sun: A Nuclear Powerhouse 567 Figure 16.5. Fusion and Fission. (a) In fusion, light atomic nuclei join together to form a heavier nuclei, releasing energy in the ... |
it fuses with a second proton. This is, however, only the average waiting time. Some of the enormous numbers of protons in the Sun’s inner region are “lucky” and take only a few collisions to achieve a fusion reaction: they are the protons responsible for producing the energy radiated by the Sun. Since the Sun is abou... |
created in the center of the Sun, finds itself in a world crammed full of fast-moving nuclei and electrons. The gamma ray collides with particles of matter and transfers its energy to one of them. The particle later emits another gamma-ray photon, but often the emitted photon has a bit less energy than the one that wa... |
) and energy in the form of gamma-ray radiation. This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 16 The Sun: A Nuclear Powerhouse 569 The second step in forming helium from hydrogen is to add another proton to the deuterium nucleus to create a helium nucleus that contains two pro... |
He + 1 H + 1 H Here, the superscripts indicate the total number of neutrons plus protons in the nucleus, e+ is the positron, v is the neutrino, and γ indicates that gamma rays are emitted. Note that the third step requires two helium-3 nuclei to start; the first two steps must happen twice before the third step can oc... |
2 pounds) of hydrogen undergoes fusion, would supply all of the electricity used in the United States for about 2 weeks. To produce the Sun’s luminosity of 4 × 1026 watts, some 600 million tons of hydrogen must be converted into helium each second, of which about 4 million tons are converted from matter into energy. As... |
like so many hopefuls in Hollywood, they will never be stars Fusion on Earth Wouldn’t it be wonderful if we could duplicate the Sun’s energy mechanism in a controlled way on Earth? (We have already duplicated it in an uncontrolled way in hydrogen bombs, but we hope our storehouses of these will never be used.) Fusion ... |
. ITER Design. The bright yellow areas in this model show where the superconducting magnets will circle the chamber within which fusion will take place. A huge magnet will keep the charged nuclei of heavy hydrogen confined. The goal is to produce 500 megawatts of energy. (credit: modification of work by Stephan Mosel) ... |
is so hot that all of the material in it is in the form of an ionized gas, called a plasma. Plasma acts much like a hot gas, which is easier to describe mathematically than either liquids or solids. The particles that constitute a gas are in rapid motion, frequently colliding with one another. This constant bombardmen... |
point by the outward force of gas pressure. The Sun maintains its stability in the following way. If the internal pressure in such a star were not great enough to balance the weight of its outer parts, the star would collapse somewhat, contracting and building up the pressure inside. On the other hand, if the pressure... |
one place to another. In conduction, atoms or molecules pass on their energy by colliding with others nearby. This happens, for example, when the handle of a metal spoon This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 16 The Sun: A Nuclear Powerhouse 575 heats up as you stir a c... |
of Spectral Lines.) The absorbed energy is always reemitted, but it can be reemitted in any direction. A photon absorbed when traveling outward in a star has almost as good a chance of being radiated back toward the center of the star as toward its surface. A particular quantity of energy, therefore, zigzags around in... |
heat energy by the particles in the surface of the skillet colliding with particles on the surface of the steak. Many cooks will put a little oil on the pan, and this layer of oil, This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 16 The Sun: A Nuclear Powerhouse 577 besides preve... |
of the Sun. Figure 16.15 schematically illustrates the predictions of a theoretical model for the Sun’s interior. Energy is generated through fusion in the core of the Sun, which extends only about one-quarter of the way to the surface but contains about one-third of the total mass of the Sun. At the center, the tempe... |
surprising. However, astronomers have indeed devised two types of measurements that can be used to obtain information about the inner parts of the Sun. One technique involves the analysis of tiny changes in the motion of small regions at the Sun’s surface. The other relies on the measurement of the neutrinos emitted b... |
to as helioseismology. It takes a little over an hour for waves to traverse the Sun from center to surface, so the waves, like neutrinos, provide information about what the solar interior is like at the present time. In contrast, remember that the sunlight we see today emerging from the Sun was actually generated in t... |
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