Chapter 7

Question 1

Mercury can be seen easily from the Earth only

Answer 1

near to the Sun, just after sunset or just before sunrise.

Question 2

Mercury is always much closer to the Sun than Venus is, and yet it never appears brighter than Venus, even when at maximum brightness. Why is this?

Answer 2

Because Mercury is small, has a dark surface, and has no reflecting clouds

Question 3

Mercury appears from spacecraft photographs to resemble the Moon in its surface features but with one important difference, which is

Answer 3

the presence of extensive plains between craters, in contrast to the surface of the Moon.

Question 4

Craters on Mercury appear to have been produced by

Answer 4

impacts from objects from space early in the planet’s history.

Question 5

What is the Caloris Basin?

Answer 5

A multi-ringed impact basin on Mercury

Question 6

The history of Mercury can be summarized as

Answer 6

thin crust formed at first, followed by extensive bombardment, the craters from which were then covered by lava flows that produced extensive lava plains between the remaining craters.

Question 7

The interior of Mercury contains

Answer 7

an iron core that occupies a large fraction of the volume of the overall planet and produces a magnetic field.

Question 8

What is the observed feature that suggests that Mercury’s iron core is molten?

Answer 8

The presence of a global magnetic field

Question 9

Where has water ice been found on Mercury?

Answer 9

In permanently shadowed crater floors at the north and south poles

Question 10

Mercury’s atmosphere is

Answer 10

almost non-existent.

Question 11

An Earth-based telescopic view of Venus shows

Answer 11

a completely cloud-shrouded planet with high atmospheric wind speeds.

Question 12

The surface temperature of Venus has been found by radio observations and by remote exploration by spacecraft to be approximately

Answer 12

750 K.

Question 13

The conditions on the surface of Venus are

Answer 13

a high pressure, high temperature, carbon dioxide atmosphere.

Question 14

The sulfuric acid clouds on Venus

Answer 14

are confined to a narrow layer about 60 km above the planet’s surface and cover the whole planet.

Question 15

The severe atmospheric conditions that quickly destroyed spacecraft that soft-landed on the surface of Venus were

Answer 15

high temperatures, high pressures, and corrosive acid clouds and mist.

Question 16

The main reason for the very high temperature (750 K) on the surface of the planet Venus is thought to be

Answer 16

the absorption of visible radiation by the Venusian surface and the subsequent trapping of infrared radiation emitted by the surface by the atmosphere and clouds.

Question 17

The geology and geography of the surface of Venus is best described as

Answer 17

mostly volcanic plains, with two continent-sized uplands, and a number of large volcanoes.

Question 18

The reason why very few impact craters are seen on Venus compared to the Moon is believed to be that

Answer 18

lava flows and surface melting have covered all but the most recent craters.

Question 19

Venus has

Answer 19

no magnetic field.

Question 20

The so-called “canals” that Schiaparelli and Lowell reported seeing on the surface of Mars were actually

Answer 20

optical illusions.

Question 21

The overall geography of Mars can best be summarized as

Answer 21

major volcanoes in the northern hemisphere extensively cratered plains in the southern hemisphere, separated by one major valley system.

Question 22

Olympus Mons is

Answer 22

a volcano on Mars.

Question 23

A caldera is

Answer 23

a crater formed by collapse at the summit of a volcano.

Question 24

What are the Valles Marineris?

Answer 24

A large rift valley system associated with the great volcanoes on Mars

Question 25

The distinctive red color of Mars is probably caused by

Answer 25

iron oxides or rust in the soil.