Question 1

Which planet is most like Venus in size and mass?

Accepted Answer

Earth is most like Venus in terms of size and mass, making them often referred to as "sister planets."

Question 2

Why did ejecta from impact craters travel farther from craters on the Moon than from craters on Mercury?

Accepted Answer

The larger the planet's gravity, the heavier the impact ejecta will be and the less distance it will travel from the impact site. Since Mercury has a larger gravity than the Moon, the ejecta from its impact craters will not travel as far from the crater as those on the Moon.

Question 3

Which of the following places has a crater density that is similar to that of Mercury?

Accepted Answer

Lunar terrae, also known as the lunar highlands, have a crater density similar to that of Mercury. This is because both surfaces are old and have been exposed to space for a long time, accumulating impacts over billions of years.

Question 4

Which of the following best describes the rotation of Venus?

Accepted Answer

Venus rotates slowly on its axis in a direction opposite to that of most planets in the solar system, which is described as slow and backward (retrograde) rotation.

Question 5

The Earth has a surface temperature of 300 K.The wavelength at which the Earth is brightest is 10 microns.The dayside of Mercury is brightest at 4 microns.Which of the following is closest to the temperature on the dayside of Mercury?

Accepted Answer

According to Wien's displacement law, the wavelength at which a blackbody emits the most radiation is inversely proportional to its temperature. Thus, for a blackbody emitting most strongly at 10 microns (like the Earth), we have:

λ_max = b/T
where b is Wien's displacement constant. Solving for T, we find:

T = b/λ_max = 2.898 x 10^-3 m K / 10 x 10^-6 m = 289.8 K

For a blackbody emitting most strongly at 4 microns (like the dayside of Mercury), we have:

λ_max = b/T
Solving for T, we find:

T = b/λ_max = 2.898 x 10^-3 m K / 4 x 10^-6 m = 724.5 K

Therefore, the closest choice is 750 K.

Question 6

The atmosphere on Mercury

Accepted Answer

The atmosphere on Mercury is very thin compared to that of Earth. In fact, Mercury's atmosphere is so tenuous that scientists often refer to it as an exosphere rather than a true atmosphere. While there are trace amounts of some gases present, including helium, hydrogen, and oxygen, the overall composition of Mercury's exosphere is very different from that of Earth's atmosphere. Carbon monoxide is not a major component of the exosphere on Mercury. The opacity of the exosphere would not prevent us from seeing the surface, as the exosphere is so thin that it does not significantly affect the passage of light.

Question 7

In which of the following circumstances can Mercury be observed?

Accepted Answer

Mercury can be observed setting at sunset because it is an inferior planet and is visible shortly after sunset or before sunrise, but never high in the sky at midnight.

Question 8

Which of the following explanations best accounts for the high density of the planet Mercury?

Accepted Answer

Mercury contains a large fraction of iron and other metal which gives it a high density.

Question 9

Why are there more craters on Mercury,than on Venus,Earth,and Mars?

Accepted Answer

Mercury has less geological activity compared to Venus, Earth, and Mars, which means that the craters formed by impacts are not erased or covered by processes such as volcanism, tectonics, and erosion as they are on the other planets. This preservation of craters gives Mercury its heavily cratered appearance.

Question 10

What can be said regarding Mercury's surface temperature?

Accepted Answer

Mercury experiences the largest temperature fluctuations between day and night in the solar system due to its lack of a significant atmosphere to distribute heat.

Question 11

Why are the craters on Mercury generally larger than lunar craters?

Accepted Answer

The surface gravity on Mercury is about two and a half times stronger than the surface gravity on the Moon. This means that meteoroids striking Mercury would hit the surface with more force, leading to larger craters.

Question 12

On which planet(s)would an explorer see the Sun rise in the west?

Accepted Answer

Venus is unique among the planets in our solar system because it rotates on its axis in the opposite direction to most planets, including Earth. This retrograde rotation means that on Venus, the Sun would appear to rise in the west and set in the east.

Question 13

Why is Mercury difficult to observe?

Accepted Answer

Mercury is difficult to observe because it orbits close to the Sun, making it appear near the Sun in the sky from Earth's perspective. This proximity means it is often lost in the Sun's glare and only visible for short periods after sunset or before sunrise.

Question 14

Why are there few spiral patterns seen in ultraviolet images of the clouds of Venus?

Accepted Answer

The slow rotation rate of Venus means that there is less Coriolis effect to create spiral patterns in the clouds.

Question 15

Which of the following is true about Mercury's rotation?

Accepted Answer

Mercury's rotation period is indeed influenced by tidal forces from the Sun, leading to a unique 3:2 spin-orbit resonance. This means Mercury rotates three times on its axis for every two orbits it completes around the Sun.

Question 16

Which of the following objects has a surface that least resembles that of Mercury?

Accepted Answer

Venus has a surface that least resembles that of Mercury, primarily because Venus is covered in thick clouds, has a very dense atmosphere, and exhibits volcanic activity, which is quite different from Mercury's heavily cratered, thin-atmosphere surface.

Question 17

The scarps that cut across the surface of Mercury probably were

Accepted Answer

Scarps on Mercury are generally believed to be the result of the planet's crust contracting as it cooled, causing the surface to buckle and create the steep cliffs that we observe. This process is a form of tectonic activity, but not associated with the kind of plate movements that occur on Earth, ruling out options A and D. Although impacts have played a role in shaping the surface of Mercury, they are not likely to have caused the large-scale tectonic features observed on the planet, making option B less likely.

Question 18

What is the explanation of the large density of Mercury?

Accepted Answer

Mercury has a large iron-nickel core, which contributes to its high density.

Question 19

The surface temperature of Mercury is high primarily because of

Accepted Answer

The surface temperature of Mercury is high primarily because of solar heating. Mercury is the closest planet to the Sun, and its surface temperature can reach up to 800 degrees Fahrenheit (427 degrees Celsius) during the day due to the intense solar radiation.

Question 20

How do we know that Mercury contains a higher percentage of iron than does the Earth?

Accepted Answer

Mercury's density is about the same as that of Earth, suggesting that it has a higher percentage of heavy elements such as iron in its composition. The other options do not provide direct evidence for the higher percentage of iron in Mercury.

Quiz 10: Mercury and Venus