Chapter 7

Based on the frequency with which we see comets from Earth, astronomers estimate the total number of comets in the solar system to be

1 trillion

About how fast was it traveling on average?

3.6

Which jovian planet does not have rings?

All the jovian planets have rings.

Suppose you view the solar system from high above Earth's North Pole. Which of the following statements about planetary orbits will be true?

All the planets orbit counterclockwise around the Sun.

The Cassini mission to Saturn consists of:

An orbiter that orbits Saturn and a probe that descended to the surface of Titan.

Which of the following most clearly distinguishes asteroids and comets from planets?

Asteroids and comets are much smaller than planets.

How do asteroids differ from comets?

Asteroids are rocky bodies and are denser than the comets, which are made of icy material.

Which of the following is not a real difference between asteroids and comets?

Asteroids orbit the Sun, whereas comets just float randomly around in the Oort cloud.

Venus has a higher average surface temperature than Mercury. Why?

Because its surface is heated by an extreme greenhouse effect.

Where are most of the known asteroids found?

Between Mars and Jupiter

In what way is Venus most similar to Earth?

Both planets are nearly the same size.

Why was it advantageous for the Voyager mission to consist of flybys rather than orbiters?

Each individual spacecraft was able to visit more than one planet.

All the planets in the solar system have at least one moon.

False

Our Moon is about the same size as moons of the other terrestrial planets.

False

The planet Uranus held a special place in the mythology of the ancient Romans

False

Moons cannot have atmospheres, active volcanoes, or liquid water.

Fase

How is Einstein's famous equation, E=mc2, important in understanding the Sun?

It explains the fact that the Sun generates energy to shine by losing some 4 million tons of mass each day.

Which of the following is not true of Mercury?

It has been studied closely by several NASA spacecraft.

How does the Sun's mass compare with that of the planets?

It is a thousand times more massive than all the planets combined.

In what way is Pluto more like a comet than a planet?

It is made mostly of rock and ice.

Which of the following statements about Pluto is not true?

It is the largest known object that is considered to be a dwarf planet.

Which of the following statements about the object called Eris is not true?

It is thought to be the first example of a new class of object.

Why has NASA sent recent orbiters to Mars on trajectories that required them to skim through Mars's atmosphere ("aerobraking") before settling into their final orbits?

It saved money because the spacecraft used atmospheric drag to slow down rather than needing to carry enough fuel to slow by firing rocket engines.

Imagine that an alien spaceship crashed onto Earth. Which statement would most likely be true?

It would crash in the ocean.

What is the Oort Cloud?

It's not really a cloud at all, but rather refers to the trillion or so comets thought to orbit the Sun at great distances.

Pluto is different from the outer planets in all of the following ways except which one?

Its surface temperature is very cold.

Now consider the second major characteristics (two types of planets). Which of the following statements are true?

Jovian planets: have more moons than terrestrial planets Orbit farther from the Sun than terrestrial planets Are larger in size than terrestrial planets Are larger in mass than terrestrial planets

The Jovian planets in our solar system are

Jupiter, Saturn, Uranus, Neptune

Astronomers have decided that, rather than being a planet, Pluto is really just a large member of

Kuiper Belt

Which planet, other than Earth, has visible water ice on it?

Mars

The most metal-rich terrestrial planet is

Mercury

The terrestrial planets in our solar system are

Mercury, Venus, Earth, Mars

Which of the following statements is not an observed pattern of motion in our solar system?

Most planets orbit at the same speed.

Which of the following is not a major pattern of motion in the solar system

Nearly all comets orbit the Sun in same direction and roughly the same plane.

All the following statements are true. Which of them are considered to be "exceptions" to the general trends described by the first three major characteristics of the solar system

Our moon has a diameter more than 1/4 the diameter of Earth Venus rotates with an axis tilt that lies nearly in the ecliptic plane. Uranus rotates with an axis tilt that lies nearly in the ecliptic plane

Which of the following is not a pattern of motion in our solar system?

Planets all rotate in the same direction.

Study the features relating to the first characteristic (orderly motions); click on the inner or outer solar system to see the planets in motion, then scroll over the planets to see diagrams of their axis tilts. Which of the following correctly describe patterns of motion in the solar system?

Planets closer to the Sun move around their orbits at higher speed than planets farther from the Sun. All the planets (not Pluto) orbit the Sun in nearly the same plane. All the planets (not Pluto) have nearly circular orbits

Which of the following is not a major difference between the terrestrial and Jovian planets in our solar system

Terrestrial planets contain large quantities of ice and jovian planets do not.

Consider the following statement: "Rocky asteroids are found primarily in the asteroid belt and Kuiper belt, whereas icy comets are found primarily in the Oort Cloud." What's wrong with this statement?

The Kuiper belt contains icy comets, not rocky asteroids

Which of the following statements about our Sun is not true?

The Sun's diameter is about 5 times that of Earth.

The solar system contains vast numbers of small bodies, which we call asteroids when they are rocky and comets when they are icy. These small bodies are concentrated in the region of the solar system that we call

The asteroid belt, the Kuiper belt, the Oort Cloud

The following statements are all true. Which one counts as an "exception to the rule" in being unusual for our solar system?

The diameter of Earth's Moon is about 1/4 that of Earth.

By studying the data in the table below, choose the correct description how escape velocity is related to mass and radius. Is the trend what you expect based on what you learned about escape velocity in Chapter Light and Matter

The first trend is that the more massive planets all have higher Ed ape velocities than the less massive planets. Neptune is somewhat more massive than Uranus and has a slightly smaller radius. Both of these factors tend to increase the escape velocity. Neptune's escape velocity is higher than Uranus's which makes sense.

Consider only the first major feature, which concerns observed patterns of motion in the solar system. Scientifically, which of the following possible conclusions is justified from the patterns of motion alone?

The planets were not each born in a separate, random event

Consider only the observed patterns of motion in the solar system. Scientifically, which of the following possible conclusions is justified from the patterns of motion alone?

The planets were not each born in a separate, random event.

Which of the following observations indicates that conditions on Mars May have been suitable for life in the past?

There are dried-up riverbeds on Mars.

Which of the following is not a characteristic of the inner planets

They all have substantial atmospheres.

Which of the following is not a characteristic of the outer planets?

They have very few, if any, satellites.

All four of the giant outer planets-Jupiter, Saturn, Uranus, and Neptune-have rings.

True

All planets orbit the Sun in the same direction (counterclockwise as viewed from above Earth's North Pole).

True

Oceans cover more of Earth's surface than land.

True

On average, Venus is the hottest planet in the solar system-even hotter than mercury.

True

The Jovian planets have no solid surface

True

The mass of the Sun compared to the mass of all the planets combined is like the mass of an elephant compared to the mass of a cat

True

The more massive planets in the solar system tend to be less dense than the lower mass planets.

True

The weather conditions on Mars today are much different than they were in the distant past

True

Which planet listed has the most extreme seasons?

Uranus

The planet closest in size to Earth is

Venus

The planet in our solar system with the highest average surface temperature is

Venus

The planet in our solar system with the highest average surface temperature is _________.

Venus

Which planet has the highest average surface temperature, and why?

Venus, because of its dense carbon dioxide atmosphere

Which of the statements about Mars is not true?

We could survive on Mars without spacesuits, as long as we brought oxygen in scuba tanks

Which of the following is farthest from the sun?

a comet in the Oort cloud

What is the Kuiper belt?

a region of the solar system beginning just beyond the orbit of Neptune that contains many icy comets

The spacecraft called Curiosity is _____.

a rover on Mars

Which planet has a ring system?

all of the above

When we say that jovian planets contain significant amounts of hydrogen compounds, we mean all the following chemicals except _________.

carbon dioxide

Which is the densest planet in the solar system?

earth

What are the main constituents of the jovian planets?

hydrogen and helium

Where does nuclear fusion occur in the Sun?

in its core

Today, scientists have a theory (the nebular theory) that explains all the major characteristics of the solar system. In science, we expect a theory like this not only to explain the observed characteristics of our solar system but also to __________.

make testable predictions about other solar systems

Compared to the distance between Earth and Mars, the distance between Jupiter and Saturn is ______.

much larger

Now consider why the observed patterns of motion lead to the conclusion that the planets were not born in separate, random events. The reason for this conclusion is that, if the planets had been born in separate, random events, we would expect that __________.

planetary orbits would have many different orientations and directions, rather than all being in the same direction and in the same plane

Which of the following best describes Pluto in terms of the general characteristics of terrestrial and Jovian planets?

size and solid surface similar to terrestrial planets; distance similar to jovian planets

Mars has two moons that are most similar in character to:

small asteroids

Which moons are sometimes called the Galilean moons?

the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto

Which of the following is not an exception to the general patterns in the solar system?

the rings of Saturn