Astronomy Chapter 7

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

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

Where does nuclear fusion occur in the Sun?

in its core

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

Venus, because of its dense carbon dioxide atmosphere

The most metal-rich terrestrial planet is

Mercury.

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

Mars

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

Its surface temperature is very cold.

Which of the following is farthest from the Sun?

a comet in the Oort cloud

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 planet has a ring system?

A) Jupiter B) Saturn C) Uranus D) Neptune

What is the primary reason why a Pluto flyby mission would be cheaper than a Pluto orbiter?

The fuel needed for an orbiter to slow down when it reaches Pluto adds a lot of weight to the spacecraft.

What is aerobraking?

the technique of using a planetary atmosphere to change the orbit of a spacecraft

Which of the following is not an advantage of spacecraft flybys over ground-based telescope
observations?

Spacecraft can monitor changes in a planet’s atmosphere over long times.

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 an exception to the general patterns in the solar system?

the rings of Saturn

Which is the densest planet in the solar system?

Earth

The planet closest in size to Earth is

Venus.

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.

What are the main constituents of the jovian planets?

hydrogen and helium

Where are most of the known asteroids found?

between the orbits of Mars and Jupiter

How do asteroids differ from comets?

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

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.

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

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

the Kuiper belt.

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

Planets all rotate in the same direction.

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 terrestrial planets in our solar system are

Mercury, Venus, Earth, and Mars.

The jovian planets in our solar system are

Jupiter, Saturn, Uranus, and Neptune.

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

carbon dioxide.

Which of the following statements about the asteroid belt is not true?

The combined mass of all the asteroids is roughly the same as the mass of Earth.

What is the Kuiper belt?

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

What is the Oort cloud?

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

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

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

Which of the following is not true of Mercury?

It has been studied closely by several NASA spacecraft.

Which of the following statements about Mars is not true?

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

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

Venus.

Which jovian planet does not have rings?

All the jovian planets have rings.

Which moons are sometimes called the Galilean moons?

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

Which of the following statements about Pluto is not true?

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

The Cassini mission to Saturn consists of

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

Which planet (besides Earth) has been visited by the largest number of robotic spacecraft?

Mars

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.

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 while 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 is not a real difference between asteroids and comets?

Asteroids orbit the Sun while comets just float randomly around in 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.

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

much larger.

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.

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

because its surface is heated by an extreme greenhouse effect

In what way is Venus most similar to Earth?

Both planets are nearly the same size.

Which of the following statements about the recently-discovered object Eris is not true?

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

Mars has two moons that are most similar in character to

small asteroids.

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

It would crash in the ocean.

Which planet listed below has the most extreme seasons?

Uranus

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

It is made mostly of rock and ice.

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.

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.

Hubble Space Telescope

earth orbiter

the main part of the Galileo spacecraft (i.e., not its atmospheric probe)

planetary orbiter

Curiosity

lander

voyager 2

flyby

visited all four giant planets between 1979 and 1989

voyager 2

mapped most of the surface of Venus with radar observations from Venusian orbit

magellan

carried the first humans to the Moon on July 20, 1969

Apollo II

dropped a probe into Jupiter on December 7, 1995

Galileo

landed on mars in 1976

Viking 1,2

used a sky crane to lower itself to the surface of Mars

curiosity

carried a probe that landed on Titan

cassini

is soon to become the first spacecraft to fly by Pluto

new horizon

has been collecting high-resolution images of Jupiter and its moons since 1995

Galileo Orbiter

is currently in orbit around Saturn

Cassini

the only spacecraft listed that remains in Earth’s orbit

Hubble Space telescope