Universe Eighth Edition

UniverseUniverseEighth EditionEighth Edition

UniverseUniverseEighth EditionEighth Edition

Roger A. Freedman • William J. Kaufmann III

CHAPTER 7CHAPTER 7Our Solar SystemOur Solar SystemCHAPTER 7CHAPTER 7

Our Solar SystemOur Solar System

Read Chapter 8Read Chapter 8Chapter 7 Online Quiz due Monday 10/11Chapter 7 Online Quiz due Monday 10/11

Homework

7-1 The important differences between the two broad 7-1 The important differences between the two broad categories of planets: terrestrial and Joviancategories of planets: terrestrial and Jovian

7-2 The similarities and differences among the large 7-2 The similarities and differences among the large planetary satellites, including Earth’s Moonplanetary satellites, including Earth’s Moon

7-3 How the spectrum of sunlight reflected from a 7-3 How the spectrum of sunlight reflected from a planet reveals the composition of its atmosphere planet reveals the composition of its atmosphere and surfaceand surface

7-4 Why some planets have atmospheres and others 7-4 Why some planets have atmospheres and others do notdo not

By reading this chapter, you will learn

7-5 The categories of the many small bodies that 7-5 The categories of the many small bodies that also orbit the Sunalso orbit the Sun

7-6 How craters on a planet or satellite reveal the 7-6 How craters on a planet or satellite reveal the age of its surface and the nature of its interiorage of its surface and the nature of its interior

7-7 Why a planet’s magnetic field indicates a fluid 7-7 Why a planet’s magnetic field indicates a fluid interior in motioninterior in motion

7-8 How the diversity of the solar system is a result 7-8 How the diversity of the solar system is a result of its origin and evolutionof its origin and evolution

By reading this chapter, you will learn

Which of the following correctly identifies the Which of the following correctly identifies the characteristics of a Jovian planet? characteristics of a Jovian planet?

A.A. Dense (> 3000 kg/mDense (> 3000 kg/m33), made mostly of H and He, ), made mostly of H and He, many rings and moons, no solid surface many rings and moons, no solid surface

B.B. Less dense (< 3000 kg/mLess dense (< 3000 kg/m33), made mostly of H and ), made mostly of H and He, many rings and moons, no solid surface He, many rings and moons, no solid surface

C.C. Dense (> 3000 kg/mDense (> 3000 kg/m33), contains very little H and ), contains very little H and He, no rings and few moons, solid surface He, no rings and few moons, solid surface

D.D. Dense (> 3000 kg/mDense (> 3000 kg/m33), contains very little H and ), contains very little H and He, many rings and moons, no solid surface He, many rings and moons, no solid surface

E.E. Less dense (< 3000 kg/mLess dense (< 3000 kg/m33), made mostly of H and ), made mostly of H and He, no rings and few moons, no solid surface He, no rings and few moons, no solid surface

Q7.2

Which of the following correctly identifies the Which of the following correctly identifies the characteristics of a Jovian planet? characteristics of a Jovian planet?

A7.2

A.A. Dense (> 3000 kg/mDense (> 3000 kg/m33), made mostly of H and He, ), made mostly of H and He, many rings and moons, no solid surface many rings and moons, no solid surface

B.B. Less dense (< 3000 kg/mLess dense (< 3000 kg/m33), made mostly of H and ), made mostly of H and He, many rings and moons, no solid surfaceHe, many rings and moons, no solid surface

C.C. Dense (> 3000 kg/mDense (> 3000 kg/m33), contains very little H and ), contains very little H and He, no rings and few moons, solid surface He, no rings and few moons, solid surface

D.D. Dense (> 3000 kg/mDense (> 3000 kg/m33), contains very little H and ), contains very little H and He, many rings and moons, no solid surface He, many rings and moons, no solid surface

E.E. Less dense (< 3000 kg/mLess dense (< 3000 kg/m33), made mostly of H and ), made mostly of H and He, no rings and few moons, no solid surface He, no rings and few moons, no solid surface

The central peak seen in this crater is the result ofThe central peak seen in this crater is the result of

A.A. plate tectonics.plate tectonics.

B.B. a high-speed impact.a high-speed impact.

C.C. volcanic activity.volcanic activity.

D.D. another meteor another meteor impact.impact.

E.E. either A or C above.either A or C above.

Q7.5

The central peak seen in this crater is the result ofThe central peak seen in this crater is the result of

A.A. plate tectonics.plate tectonics.

B.B. a high-speed impact.a high-speed impact.

C.C. volcanic activity.volcanic activity.

D.D. another meteor another meteor impact.impact.

E.E. either A or C above.either A or C above.

A7.5

Mars is more heavily cratered than the Earth. This is Mars is more heavily cratered than the Earth. This is because because

A.A. for a long time Mars has had little geologic for a long time Mars has had little geologic activity. activity.

B.B. meteors are much more plentiful very close to meteors are much more plentiful very close to the Sun where Earth is located. the Sun where Earth is located.

C.C. long ago Mars was very hot and its surface long ago Mars was very hot and its surface formed blisters. formed blisters.

D.D. Mars is close to Jupiter, and Jupiter’s gravity Mars is close to Jupiter, and Jupiter’s gravity causes more meteors to strike Mars than Earth. causes more meteors to strike Mars than Earth.

E.E. erosion from running water has caused the erosion from running water has caused the Martian craters.Martian craters.

Q7.8

Mars is more heavily cratered than the Earth. This is Mars is more heavily cratered than the Earth. This is because because

A.A. for a long time Mars has had little geologic for a long time Mars has had little geologic activity.activity.

B.B. meteors are much more plentiful very close to meteors are much more plentiful very close to the Sun where Earth is located. the Sun where Earth is located.

C.C. long ago Mars was very hot and its surface long ago Mars was very hot and its surface formed blisters. formed blisters.

D.D. Mars is close to Jupiter, and Jupiter’s gravity Mars is close to Jupiter, and Jupiter’s gravity causes more meteors to strike Mars than Earth. causes more meteors to strike Mars than Earth.

E.E. erosion from running water has caused the erosion from running water has caused the Martian craters.Martian craters.

A7.8

Which of the following correctly identifies the Which of the following correctly identifies the characteristics of a terrestrial planet? characteristics of a terrestrial planet?

A.A. Dense (> 3000 kg/mDense (> 3000 kg/m33), made mostly of H and He, ), made mostly of H and He, many rings and moons, no solid surface many rings and moons, no solid surface

B.B. Less dense (< 3000 kg/mLess dense (< 3000 kg/m33), made mostly of H and ), made mostly of H and He, many rings and moons, no solid surface He, many rings and moons, no solid surface

C.C. Dense (> 3000 kg/mDense (> 3000 kg/m33), contains very little H and ), contains very little H and He, no rings and few moons, solid surface He, no rings and few moons, solid surface

D.D. Dense (> 3000 kg/mDense (> 3000 kg/m33), contains very little H and ), contains very little H and He, many rings and moons, no solid surface He, many rings and moons, no solid surface

E.E. Less dense (< 3000 kg/mLess dense (< 3000 kg/m33), made mostly of H and ), made mostly of H and He, no rings and few moons, no solid surface He, no rings and few moons, no solid surface

Q7.1

Which of the following correctly identifies the Which of the following correctly identifies the characteristics of a terrestrial planet? characteristics of a terrestrial planet?

A.A. Dense (> 3000 kg/mDense (> 3000 kg/m33), made mostly of H and He, ), made mostly of H and He, many rings and moons, no solid surface many rings and moons, no solid surface

B.B. Less dense (< 3000 kg/mLess dense (< 3000 kg/m33), made mostly of H and ), made mostly of H and He, many rings and moons, no solid surface He, many rings and moons, no solid surface

C.C. Dense (> 3000 kg/mDense (> 3000 kg/m33), contains very little H and ), contains very little H and He, no rings and few moons, solid surfaceHe, no rings and few moons, solid surface

D.D. Dense (> 3000 kg/mDense (> 3000 kg/m33), contains very little H and ), contains very little H and He, many rings and moons, no solid surface He, many rings and moons, no solid surface

E.E. Less dense (< 3000 kg/mLess dense (< 3000 kg/m33), made mostly of H and ), made mostly of H and He, no rings and few moons, no solid surface He, no rings and few moons, no solid surface

A7.1

Key Ideas

Properties of the Planets:Properties of the Planets: All of the planets orbit the All of the planets orbit the Sun in the same direction and in almost the same plane. Sun in the same direction and in almost the same plane. Most of the planets have nearly circular orbits.Most of the planets have nearly circular orbits.

The four inner planets are called terrestrial planets. They The four inner planets are called terrestrial planets. They are relatively small (with diameters of 5000 to 13,000 are relatively small (with diameters of 5000 to 13,000 km), have high average densities (4000 to 5500 kg/m3), km), have high average densities (4000 to 5500 kg/m3), and are composed primarily of rocky materials.and are composed primarily of rocky materials.

The four giant outer planets are called Jovian planets. The four giant outer planets are called Jovian planets. They have large diameters (50,000 to 143,000 km) and They have large diameters (50,000 to 143,000 km) and low average densities (700 to 1700 kg/m3) and are low average densities (700 to 1700 kg/m3) and are composed primarily of light elements such as hydrogen composed primarily of light elements such as hydrogen and helium.and helium.

Key Ideas

Satellites and Small Bodies in the Solar System:Satellites and Small Bodies in the Solar System: Besides the planets, the solar system includes satellites Besides the planets, the solar system includes satellites of the planets, asteroids, comets, and trans-Neptunian of the planets, asteroids, comets, and trans-Neptunian objects.objects.

Seven large planetary satellites (one of which is our Seven large planetary satellites (one of which is our Moon) are comparable in size to the planet Mercury. The Moon) are comparable in size to the planet Mercury. The remaining satellites of the solar system are much remaining satellites of the solar system are much smaller.smaller.

Key Ideas

Asteroids are small, rocky objects, while comets and Asteroids are small, rocky objects, while comets and trans-Neptunian objects are made of ice and rock. All are trans-Neptunian objects are made of ice and rock. All are remnants left over from the formation of the planets.remnants left over from the formation of the planets.

Most asteroids are found in the asteroid belt between the Most asteroids are found in the asteroid belt between the orbits of Mars and Jupiter, and most trans-Neptunian orbits of Mars and Jupiter, and most trans-Neptunian objects lie in the Kuiper belt outside the orbit of Neptune. objects lie in the Kuiper belt outside the orbit of Neptune. Pluto is one of the largest members of the Kuiper belt.Pluto is one of the largest members of the Kuiper belt.

Key Ideas

Spectroscopy and the Composition of the Planets:Spectroscopy and the Composition of the Planets: Spectroscopy, the study of spectra, provides information Spectroscopy, the study of spectra, provides information about the chemical composition of objects in the solar about the chemical composition of objects in the solar system.system.

The spectrum of a planet or satellite with an atmosphere The spectrum of a planet or satellite with an atmosphere reveals the atmosphere’s composition. If there is no reveals the atmosphere’s composition. If there is no atmosphere, the spectrum indicates the composition of atmosphere, the spectrum indicates the composition of the surface.the surface.

The substances that make up the planets can be The substances that make up the planets can be classified as gases, ices, or rock, depending on the classified as gases, ices, or rock, depending on the temperatures at which they solidify.temperatures at which they solidify.

Key Ideas

Impact Craters:Impact Craters: When an asteroid, comet, or meteoroid When an asteroid, comet, or meteoroid collides with the surface of a terrestrial planet or satellite, collides with the surface of a terrestrial planet or satellite, the result is an impact crater.the result is an impact crater.

Geologic activity renews the surface and erases craters, Geologic activity renews the surface and erases craters, so a terrestrial world with extensive cratering has an old so a terrestrial world with extensive cratering has an old surface and little or no geologic activity.surface and little or no geologic activity.

Because geologic activity is powered by internal heat, Because geologic activity is powered by internal heat, and smaller worlds lose heat more rapidly, as a general and smaller worlds lose heat more rapidly, as a general rule smaller terrestrial worlds are more extensively rule smaller terrestrial worlds are more extensively cratered.cratered.

Key Ideas

Magnetic Fields and Planetary Interiors:Magnetic Fields and Planetary Interiors: Planetary Planetary magnetic fields are produced by the motion of electrically magnetic fields are produced by the motion of electrically conducting liquids inside the planet. This mechanism is conducting liquids inside the planet. This mechanism is called a dynamo. If a planet has no magnetic field, that is called a dynamo. If a planet has no magnetic field, that is evidence that there is little such liquid material in the evidence that there is little such liquid material in the planet’s interior or that the liquid is not in a state of planet’s interior or that the liquid is not in a state of motion.motion.

The magnetic fields of terrestrial planets are produced by The magnetic fields of terrestrial planets are produced by metals such as iron in the liquid state. The stronger fields metals such as iron in the liquid state. The stronger fields of the Jovian planets are generated by liquid metallic of the Jovian planets are generated by liquid metallic hydrogen or by water with ionized molecules dissolved in hydrogen or by water with ionized molecules dissolved in it.it.