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ormation. The second way we try to keep numbers simple is to use a consistent set of units—the metric International System of Units, or SI (from the French Système International d’Unités). The metric system is summarized in Appendix D (see Example 1.2). 16 Chapter 1 Science and the Universe: A Brief Tour Watch this bri... |
ant size that orbits a star and does not produce its own light. (If a large body consistently produces its own light, it is then called a star.) Later in the book this definition will be modified a bit, but it is perfectly fine for now as you begin your voyage. Figure 1.8. Our Solar Family. The Sun, the planets, and so... |
her small galaxy groups, and then at about 50 million light- years there are more impressive systems with thousands of member galaxies. We have discovered that galaxies occur mostly in clusters, both large and small (Figure 1.14). 26 Chapter 1 Science and the Universe: A Brief Tour Figure 1.14. Fornax Cluster of Galaxi... |
sents a classic overview of astronomy by an astronomer who had a true gift for explaining things clearly. (You can also check out Sagan’s television series Cosmos: A Personal Voyage and Neil DeGrasse Tyson’s current series Cosmos: A Spacetime Odyssey.) 30 Chapter 1 Science and the Universe: A Brief Tour Tyson, Neil DeG... |
al Equator To help orient us in the turning sky, astronomers use a system that extends Earth’s axis points into the sky. Imagine a line going through Earth, connecting the North and South Poles. This is Earth’s axis, and Earth rotates about this line. If we extend this imaginary line outward from Earth, the points wher... |
Pluto are actually tilted so much that they orbit the Sun “on their side.” Figure 2.7. The Celestial Tilt. The celestial equator is tilted by 23.5° to the ecliptic. As a result, North Americans and Europeans see the Sun north of the celestial equator and high in our sky in June, and south of the celestial equator and l... |
he Egyptians. The Chinese also recorded comets, bright meteors, and dark spots on the Sun. (Many types of astronomical objects were introduced in Science and the Universe: A Brief Tour. If you are not familiar with terms like comets and meteors, you may want to review that chapter.) Later, Chinese astronomers kept care... |
rence must be 50 × 5000, or 250,000 stadia. Figure 2.11. How Eratosthenes Measured the Size of Earth. Eratosthenes measured the size of Earth by observing the angle at which the Sun’s rays hit our planet’s surface. The Sun’s rays come in parallel, but because Earth’s surface curves, a ray at Syene comes straight down w... |
ns had to be circular. However, we shall see in Orbits and Gravity that the planets, like Earth, travel about the Sun in orbits that are ellipses, not circles. Their actual behavior cannot be represented accurately by a scheme of uniform circular motions. In order to match the observed motions of the planets, Ptolemy h... |
of tests are all the same: there is no evidence that natal astrology has any predictive power, even in a statistical sense. Why, then, do people often seem to have anecdotes about how well their own astrologer advised them? Effective astrologers today use the language of the zodiac and the horoscope only as the outwar... |
a roughly correct scale for the solar system. Copernicus could not prove that Earth revolves about the Sun. In fact, with some adjustments, the old Ptolemaic system could have accounted, as well, for the motions of the planets in the sky. But Copernicus pointed out that the Ptolemaic cosmology was clumsy and lacking th... |
as identical to what he saw up close. Only then could he begin to believe that the miraculous phenomena the telescope revealed in the heavens were real. Beginning his astronomical work late in 1609, Galileo found that many stars too faint to be seen with the unaided eye became visible with his telescope. In particular,... |
g the system of stellar magnitudes, and discovering precession from the apparent shift in the position of the north celestial pole. Ptolemy of Alexandria summarized classic astronomy in his Almagest; he explained planetary motions, including retrograde motion, with remarkably good accuracy using a model centered on Ear... |
h the Sun is a minor star on the outskirts of one galaxy among billions. Discuss some of the cultural and philosophical implications of each point of view. This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 2 Observing the Sky: The Birth of Astronomy 67 29. The north celestial pole ... |
circle, ellipse, parabola, and hyperbola are all formed by the intersection of a plane with a cone. This is why such curves are called conic sections. 72 Chapter 3 Orbits and Gravity You might recall from math classes that in a circle, the center is a special point. The distance from the center to anywhere on the circ... |
is 0.72 AU. Earth’s orbital period is 1.00 year, and its semimajor axis is 1.00 AU. Solution We can use the equation for Kepler’s third law, P2 ∝ a3. For Venus, P2 = 0.62 × 0.62 = 0.38 year and a3 = 0.72 × 0.72 × 0.72 = 0.37 AU (rounding numbers sometimes causes minor discrepancies like this). The orbital period (0.38... |
ry), powered by three fuel engines burning liquid oxygen and liquid hydrogen, with two solid fuel boosters, demonstrates Newton’s third law. (credit: modification of work by NASA For more about Isaac Newton’s life and work, check out this timeline page (https://openstaxcollege.org/l/30IsaacNewTime) with snapshots from ... |
Newton must have felt to realize he had discovered, and verified, a law that holds for Earth, apples, the Moon, and, as far as he knew, everything in the universe Calculating Weight By what factor would a person’s weight at the surface of Earth change if Earth had its present mass but eight times its present volume? So... |
he dwarf planet Pluto is inclined about 17° to the ecliptic, and that of the dwarf planet Eris (orbiting even farther away from the Sun than Pluto) by 44°, but all the major planets lie within 10° of the common plane of the solar system You can use an orbital simulator (https://openstaxcollege.org/l/30phetorbsim) to de... |
have been carried out with modern computers to track the evolution of hypothetical clusters of stars with up to a million members (Figure 3.13). Figure 3.13. Modern Computing Power. These supercomputers at NASA’s Ames Research Center are capable of tracking the motions of more than a million objects under their mutual... |
(called the foci) is always the same escape speed the speed a body must achieve to break away from the gravity of another body focus (plural: foci) one of two fixed points inside an ellipse from which the sum of the distances to any point on the ellipse is constant gravity the mutual attraction of material bodies or p... |
s that you know that deal with astronomy or outer space? If not, perhaps you could find some online, or by asking friends or roommates who are into poetry or music. EXERCISES Review Questions 1. State Kepler’s three laws in your own words. 2. Why did Kepler need Tycho Brahe’s data to formulate his laws? 3. Which has mo... |
longitude of the Prime Meridian is defined as 0°. This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 4 Earth, Moon, and Sky 105 Figure 4.2. Latitude and Longitude of Washington, DC. We use latitude and longitude to find cities like Washington, DC, on a globe. Latitude is the number... |
ess. (b) In winter, the Sun is low in the sky and its rays spread out over a much wider area, becoming less effective at heating the ground. The second effect has to do with the length of time the Sun spends above the horizon (Figure 4.7). Even if you’ve never thought about astronomy before, we’re sure you have observe... |
ember 21, so at the North Pole, the Sun rises when it reaches the vernal equinox and sets when it reaches the autumnal equinox. Each year there are 6 months of sunshine at each pole, followed by 6 months of darkness. This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 4 Earth, Moon, ... |
e were strictly observed, people traveling east or west would have to reset their watches continually as the longitude changed, just to read the local mean time correctly. For instance, a commuter traveling from Oyster Bay on Long Island to New York City would have to adjust the time on the trip through the East River ... |
ar had added up to the point where the first day of spring was occurring on March 11, instead of March 21. If the trend were allowed to continue, eventually the Christian celebration of Easter would be occurring in early winter. Pope Gregory XIII, a contemporary of Galileo, felt it necessary to institute further calend... |
eek after the full moon, for example, the Moon is at third quarter, meaning that it is three-quarters of the way around (not that it is three-quarters illuminated—in fact, half of the visible side of the Moon is again dark). At this phase, the Moon is now rising around midnight and setting around noon. Note that there ... |
ess than half as effective as the Moon at tide raising. The actual tides we experience are a combination of the larger effect of the Moon and the smaller effect of the Sun. When the Sun and Moon are lined up (at new moon or full moon), the tides produced reinforce each other and so are greater than normal (Figure 4.19)... |
of Earth’s surface is water, eclipse chasing can involve lengthy boat trips (and often requires air travel as well). As a result, eclipse chasing is rarely within the budget of a typical college student. Nevertheless, a list of future eclipses is given for your reference in Appendix H, just in case you strike it rich e... |
d be a prime opportunity to witness this extraordinary spectacle Check out this useful booklet (https://openstaxcollege.org/l/302017ecliboo) about the 2017 eclipse (with specific times in different locations). 136 Chapter 4 Earth, Moon, and Sky CHAPTER 4 REVIEW KEY TERMS apparent solar time time as measured by the posi... |
verters and many other historical and mathematical tools. Walk through Time: The Evolution of Time Measurement through the Ages (National Institute of Standards and Technology): http://www.nist.gov/pml/general/time/. Videos Bill Nye, the Science Guy, Explains the Seasons: https://www.youtube.com/watch?v=KUU7IyfR34o. Fo... |
.26 Earth-days (for Deimos) to circle the planet. You are given the task of coming up with a martian calendar for a new Mars colony. Would a solar or lunar calendar be better for tracking the seasons? 36. What is the right ascension and declination of the vernal equinox? This OpenStax book is available for free at http... |
and forth) and found that the resulting pattern of electric and magnetic fields would spread out and travel rapidly through space. Something similar happens when a raindrop strikes the surface of water or a frog jumps into a pond. The disturbance moves outward and creates a pattern we call a wave in the water (Figure 5... |
others was a very surprising and unlikely idea. After all, our common sense says that waves and particles are opposite concepts. On one hand, a wave is a repeating disturbance that, by its very nature, is not in only one place, but spreads out. A particle, on the other hand, is something that can be in only one place a... |
d the nerve endings in our skin are sensitive to this band of the electromagnetic spectrum. Infrared waves are absorbed by water and carbon dioxide molecules, which are more concentrated low in Earth’s atmosphere. For this reason, infrared astronomy is best done from high mountaintops, high-flying airplanes, and spacec... |
e to indicate cold temperatures. Although these are common uses to us in daily life, in nature, it’s the other way around.) We can develop a more precise star thermometer by measuring how much energy a star gives off at each wavelength and by constructing diagrams like Figure 5.8. The location of the peak (or maximum) ... |
nd Spectra 163 Figure 5.11. Visible Spectrum of the Sun. Our star’s spectrum is crossed by dark lines produced by atoms in the solar atmosphere that absorb light at certain wavelengths. (credit: modification of work by Nigel Sharp, NOAO/National Solar Observatory at Kitt Peak/AURA, and the National Science Foundation) ... |
most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you.” This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 5 Radiation and Spectra 167 Figure 5.14. Rutherfor... |
waves. As electrons move from one level to another, they give off or absorb little packets of energy. When an electron moves to a higher level, it absorbs a photon of just the right energy (provided one is available). When it moves to a lower level, it emits a photon with the exact amount of energy it no longer needs i... |
gher and higher energy levels, the levels become more and more crowded together, approaching a limit. The region above the top line represents energies at which the atom is ionized (the electron is no longer attached to the atom). Each series of arrows represents electrons falling from higher levels to lower ones, rele... |
the speed of light through empty space, no matter what. This means that motion cannot affect the speed, but only the wavelength and the frequency. As the wavelength decreases, the frequency must increase. If the waves are shorter, more will be able to move by during each second.) The situation is not the same for othe... |
gains or loses electrons isotope any of two or more forms of the same element whose atoms have the same number of protons but different numbers of neutrons microwave electromagnetic radiation of wavelengths from 1 millimeter to 1 meter; longer than infrared but shorter than radio waves 182 Chapter 5 Radiation and Spect... |
he electromagnetic spectrum? 2. What is a wave? Use the terms wavelength and frequency in your definition. 3. Is your textbook the kind of idealized object (described in section on radiation laws) that absorbs all the radiation falling on it? Explain. How about the black sweater worn by one of your classmates? 4. Where... |
to white to blue with increasing energy of the X-rays. The bright, hot stars in Orion are still seen in this image, but so are many other objects located at very different distances, including other stars, star corpses, and galaxies at the edge of the observable universe. (c) Infrared radiation: here, we mainly see th... |
must pass through the lens of a refractor. That means the glass must be perfect all the way through, and it has proven very difficult to make large pieces of glass without flaws and bubbles in them. Also, optical properties of transparent materials change a little bit with the wavelengths (or colors) of light, so there... |
Mauna Kea, HI Completed 1993–96 www.keckobservatory.org Hobby–Eberly Telescope (HET) Mount Locke, TX Completed 1997 www.as.utexas.edu/ mcdonald/het Large Binocular Telescope (LBT) (two telescopes) Large Synoptic Survey Telescope (LSST) Mount Graham, AZ First light 2004 www.lbto.org The Cerro Pachón, Chile First light ... |
but also by its location. Earth’s atmosphere, so vital to life, presents challenges for the observational astronomer. In at least four ways, our air imposes limitations on the usefulness of telescopes: 1. The most obvious limitation is weather conditions such as clouds, wind, and rain. At the best sites, the weather is... |
year before you get another chance. Some older astronomers still remember long, cold nights spent alone in an observatory dome, with only music from a tape recorder or an all-night radio station for company. The sight of the stars shining brilliantly hour after hour through the open slit in the observatory dome was un... |
rning Objectives By the end of this section, you will be able to: Describe how radio waves from space are detected Identify the world’s largest radio telescopes Define the technique of interferometry and discuss the benefits of interferometers over single-dish telescopes In addition to visible and infrared radiation, r... |
1 kilometer across). To get even better resolution, astronomers combine a large number of radio dishes into an interferometer array. In effect, such an array works like a large number of two-dish interferometers, all observing the same part of the sky together. Computer processing of the results permits the reconstruc... |
ect by the United States, the Netherlands, and Britain. IRAS was equipped with a 0.6-meter telescope cooled to a temperature of less than 10 K. For the first time, the infrared sky could be seen as if it were night, rather than through a bright foreground of atmospheric and telescope emissions. IRAS carried out a rapid... |
stable orbit point, some 1.5 million kilometers This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 6 Astronomical Instruments 223 from Earth (where no astronauts can currently travel if it needs repair.) The telescope is scheduled for launch in 2018 and should have the sensitivity ... |
R EXPLORATION Articles Blades, J. C. “Fixing the Hubble One Last Time.” Sky & Telescope (October 2008): 26. On the last Shuttle service mission and what the Hubble was then capable of doing. Brown, A. “How Gaia will Map a Billion Stars.” Astronomy (December 2014): 32. Nice review of the mission to do photometry and spe... |
rs are visible per square degree? Per square arcsecond? 27. Theoretically (that is, if seeing were not an issue), the resolution of a telescope is inversely proportional to its diameter. How much better is the resolution of the ALMA when operating at its longest baseline than the resolution of the Arecibo telescope? 28... |
ut others have been discovered during the twenty- first century. One of them, Eris, is about the same size as Pluto and has at least one moon (Pluto has five known moons.) The largest TNOs are also classed as dwarf planets, as is the largest asteroid, Ceres. (Dwarf planets will be discussed further in the chapter on Ri... |
the ground is known as a meteorite. (You can see meteorites on display in many natural history museums and can sometimes even purchase pieces of them from gem and mineral dealers.) Carl Sagan: Solar System Advocate The best-known astronomer in the world during the 1970s and 1980s, Carl Sagan devoted most of his profes... |
ter gods of fire and thunder from the mythologies of many cultures. Craters on Mercury commemorate famous novelists, playwrights, artists, and composers. On Saturn’s moon Tethys, all the features are named after characters and places in Homer’s great epic poem, The Odyssey. As we explore further, it may well turn out t... |
n habitation. Any bases we build in the systems of the giant planets may well have to be in space or one of their moons—none of which is particularly hospitable to a luxury hotel with a swimming pool and palm trees. Perhaps we will find warmer havens deep inside the clouds of Jupiter or in the ocean under the frozen ic... |
n the appearance of the rock; the splashes of color are shown here for conceptual purposes only. If you had 1 gram of pure radioactive nuclei with a half-life of 100 years, then after 100 years you would have 1/2 gram; after 200 years, 1/4 gram; after 300 years, only 1/8 gram; and so forth. However, the material does n... |
and in the opposite direction from the other planets? Why does the composition of the Moon resemble Earth in many ways and yet exhibit substantial differences? The answers to such questions probably lie in enormous collisions that took place in the solar system long before life on Earth began. Today, some 4.5 billion ... |
terpreting their field of research for the public? This OpenStax book is available for free at http://cnx.org/content/col11992/1.8 Chapter 7 Other Worlds: An Introduction to the Solar System 261 Why or why not? Are there ways that scientists who are not as eloquent or charismatic as Carl Sagan or Neil deGrasse Tyson ca... |
Earth’s Crust 8.3 Earth’s Atmosphere 8.4 Life, Chemical Evolution, and Climate Change 8.5 Cosmic Influences on the Evolution of Earth Thinking Ahead Airless worlds in our solar system seem peppered with craters large and small. Earth, on the other hand, has few craters, but a thick atmosphere and much surface activity... |
nd sometimes farther. The magnetosphere was discovered in 1958 by instruments on the first US Earth satellite, Explorer 1, which recorded the ions (charged particles) trapped in its inner part. The regions of high-energy ions in the magnetosphere are often called the Van Allen belts in recognition of the University of ... |
). Four years later, on his fourth expedition to his beloved Greenland, he celebrated his fiftieth birthday with colleagues and then set off on foot toward a different camp on the island. He never made it; he was found a few days later, dead of an apparent heart attack. 274 Chapter 8 Earth as a Planet Critics of scienc... |
S Geological Service provides an interactive map (https://openstax.org/l/30mapringoffire) of the famous “ring of fire,” which is the chain of volcanoes surrounding the Pacific Ocean, and shows the Hawaiian “hot spot” enclosed within. Not all volcanic eruptions produce mountains. If lava flows rapidly from long cracks, ... |
0 meters, flooding many coastal cities and ports, and putting small islands completely under water. The best documented changes in Earth’s climate are the great ice ages, which have lowered the temperature of the Northern Hemisphere periodically over the past half million years or so (Figure 8.14). The last ice age, wh... |
n a planetary scale, one of the consequences of life has been a decrease in atmospheric carbon dioxide. In the absence of life, Earth would probably have an atmosphere dominated by CO2, like Mars or Venus. But living things, in combination with high levels of geological activity, have effectively stripped our atmospher... |
e kilometers of forest (Figure 8.20). Herds of reindeer and other animals were killed, and a man at a trading post 80 kilometers from the blast was thrown from his chair and knocked unconscious. The blast wave spread around the world, as recorded by instruments designed to measure changes in atmospheric pressure. 290 C... |
life are not necessarily a thing of the past. In the full scope of planetary history, 65 million years ago was just yesterday. Earth actually orbits the Sun within a sort of cosmic shooting gallery, and although major impacts are rare, they are by no means over. Humanity could suffer the same fate as the dinosaurs, or... |
tos and eyewitness reporting. Gasperini, L., et al. “The Tunguska Mystery.” Scientific American (June 2008): 80. A more detailed exploration of the site of the 1908 impact over Siberia. Kring, D. “Blast from the Past.” Astronomy (August 2006): 46. Six-page introduction to Arizona’s meteor crater. Websites Earth Astrona... |
(this would be true even if the human species as a whole survived). Such impact events are random, and one could take place at any time. Calculate the probability that such an impact will occur within the next 50 years (within your lifetime). 29. How do the risks of dying from the impact of an asteroid or comet compare... |
Houston, although it has been moved indoors since this photo was taken. (credit: modification of work by David Morrison) Lunar exploration has become an international enterprise with many robotic spacecraft focusing on lunar science. The USSR sent a number in the 1960s, including robot sample returns. Table 9.3 lists ... |
ion years ago. Its outer ring is about 1000 kilometers in diameter, roughly the distance between New York City and Detroit, Michigan. Unlike most of the other basins, Orientale has not been completely filled in with lava flows, so it retains its striking “bull’s-eye” appearance. It is located on the edge of the Moon as... |
ers. This is because sunlight illuminates the surface straight on, and in this flat lighting, no shadows are cast. Much more revealing is the view near first or third quarter, when sunlight streams in from the side, causing topographic features to cast sharp shadows. It is almost always more rewarding to study a planet... |
asing evidence that large chunks of material—objects of essentially planetary mass—were orbiting in the inner solar system at the time that the terrestrial planets formed. The giant impact hypothesis envisions Earth being struck obliquely by an object approximately one-tenth Earth’s mass—a “bullet” about the size of Ma... |
ce the size it appears from Earth). As the Sun rises higher and higher, it looks bigger and bigger; Mercury is now getting closer to the Sun in its eccentric orbit. At the same time, the apparent motion of the Sun slows down as Mercury’s faster motion in orbit begins to catch up with its rotation. At noon, the Sun is n... |
l, T. “Warning: Dust Ahead.” Astronomy (March 2006): 46. What we know about lunar dust and the problems it can cause. Dorminey, B. “Secrets beneath the Moon’s Surface.” Astronomy (March 2011): 24. A nice timeline of the Moon’s evolution and the story of how we are finding out more about its internal structure. Jayaward... |
an asteroid? 26. Why are the lunar mountains smoothly rounded rather than having sharp, pointed peaks (as they were almost always depicted in science-fiction illustrations and films before the first lunar landings)? 27. The lunar highlands have about ten times more craters in a given area than do the maria. Does this m... |
ells talk to the Cabots And the Cabots talk only to God. Percival’s brother Lawrence became president of Harvard University, and his sister, Amy, became a distinguished poet. Percival was already interested in astronomy as a boy: he made observations of Mars at age 13. His undergraduate thesis at Harvard dealt with the... |
d from the US Magellan spacecraft, which mapped Venus with a powerful imaging radar. Magellan produced images with a resolution of 100 meters, much better than that of previous missions, yielding our first detailed look at the surface of our sister planet (Figure 10.6). (The Magellan spacecraft returned more data to Ea... |
nd most of the mountains of Venus also owe their existence to tectonic forces. Figure 10.10. Ridges and Cracks. This region of the Lakshmi Plains on Venus has been fractured by tectonic forces to produce a cross-hatched grid of cracks and ridges. Be sure to notice the fainter linear features that run perpendicular to t... |
conclusion that we and our descendants will surely want to pay close attention to. 350 Chapter 10 Earthlike Planets: Venus and Mars 10.4 THE GEOLOGY OF MARS Learning Objectives By the end of this section, you will be able to: Discuss the main missions that have explored Mars Explain what we have learned from examinatio... |
would be very difficult for ejecta from impacts on Venus to escape through its thick atmosphere. By the process of elimination, the only reasonable origin seems to be Mars, where the Tharsis volcanoes were active at that time. The martian origin of these meteorites was confirmed by the analysis of tiny gas bubbles tra... |
in areas that apparently were flooded sometime in the past, where sedimentary rock layers, formed in the presence of water, are common. (Although we should note that nearly all the planet is blanketed in at least a thin layer of wind-blown dust). The Viking landers included weather stations that operated for several ye... |
that cover the older cratered ground below. Individual layers are typically ten to a few tens of meters thick, marked by alternating light and dark bands of sediment. Probably the material in the polar deposits includes dust carried by wind from the equatorial regions of Mars. What do these terraced layers tell us abo... |
ker—allowing water to be liquid on the surface. Spirit was specifically targeted to explore what looked like an ancient lake-bed in Gusev crater, with an outflow channel emptying into it. However, when the spacecraft landed, it found that the former lakebed had been covered by thin lava flows, blocking the rover from a... |
analyzed it carefully to determine what organic (carbon-bearing) material it contained. The Viking experiments were so sensitive that, had one of the spacecraft landed anywhere on Earth (with the possible exception of Antarctica), it would easily have detected life. But, to the disappointment of many scientists and mem... |
reas the southern permanent ice cap is made predominantly of water ice with a covering of carbon dioxide ice. Evidence of a very different climate in the past is found in water erosion features: both runoff channels and outflow channels, the latter carved by catastrophic floods. Our rovers, exploring ancient lakebeds a... |
ght Questions 13. What are the advantages of using radar imaging rather than ordinary cameras to study the topography of Venus? What are the relative advantages of these two approaches to mapping Earth or Mars? 14. Venus and Earth are nearly the same size and distance from the Sun. What are the main differences in the ... |
pass between Earth and the spacecraft. If a problem develops near Saturn, for example, a wait of hours for the alarm to reach Earth and for instructions to be routed back to the spacecraft could spell disaster. Spacecraft to the outer solar system must therefore be highly reliable and capable of a greater degree of in... |
The Giant Planets Basic Properties of the Jovian Planets Planet Distance (AU) Period (years) Diameter (km) Mass (Earth = 1) Density (g/cm3) Rotation (hours) Jupiter Saturn 5.2 9.5 Uranus 19.2 11.9 29.5 84.1 142,800 318 120,540 51,200 95 14 17 1.3 0.7 1.3 1.6 9.9 10.7 17.2 16.1 Neptune 30.0 164.8 49,500 Table 11.3 Jupit... |
ousands of kilometers.) Internal Heat Sources Because of their large sizes, all the giant planets were strongly heated during their formation by the collapse of surrounding material onto their cores. Jupiter, being the largest, was the hottest. Some of this primordial heat can still remain inside such large planets. In... |
free at http://cnx.org/content/col11992/1.8 Chapter 11 The Giant Planets 393 The Soviet Union won the first lap of the race by launching Sputnik 1 in October 1957. The US government spurred its scientists and engineers to even greater efforts to get something into space to maintain the country’s prestige. However, the... |
is seen here as photographed by Voyager in 1989. The blue color, exaggerated with computer processing, is caused by the scattering of sunlight in the planet’s upper atmosphere. (credit: modification of work by NASA) Unlike Uranus, Neptune has an atmosphere in which convection currents—vertical drafts of gas—emanate fro... |
une in the mid-1990s, however, astronomers could find no trace of the Great Dark Spot on their images. Although many of the details of the weather on the jovian planets are not yet understood, it is clear that if you are a fan of dramatic weather, these worlds are the place to look. We study the features in these atmos... |
leave all exploration of the outer solar system to unmanned space probes? EXERCISES Review Questions 1. What are the main challenges involved in sending probes to the giant planets? 2. Why is it difficult to drop a probe like Galileo? How did engineers solve this problem? 3. Explain why visual observation of the gas g... |
us small moons, many of which we have not yet glimpsed. The Neptune System Neptune has 14 known moons. The most interesting of these is Triton, a relatively large moon in a retrograde orbit—which is unusual. Triton has a very thin atmosphere, and active eruptions were discovered there by Voyager in its 1989 flyby. To e... |
ite its mainly rocky composition, Europa has an ice-covered surface, as astronomers have long known from examining spectra of sunlight reflected from it. In this it resembles Earth, which has a layer of water on its surface, but in Europa’s case the water is capped by a thick crust of ice. There are very few impact cra... |
l surface with still-warm lava. From these measurements, it seems clear that the bright surface colors that first attracted attention to Io are the result of a thin veneer of sulfur compounds. The underlying volcanism is driven by eruptions of molten silicates, just like on Earth (Figure 12.10). This OpenStax book is a... |
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