Question 1

An atmosphere can escape a planet if the escape velocity is six times the average molecularspeed at that temperature.

Accepted Answer

This statement is based on Jean's Escape, which explains that an atmosphere can escape a planet if the escape velocity is greater than the root mean square velocity of the gas molecules. The root mean square velocity is directly proportional to the square root of the temperature, so the statement is implicitly assuming a certain temperature. Therefore, if the escape velocity is six times greater than the average molecular speed at that temperature, then the atmosphere can escape. This statement is known as Jeans escape criterion and is a widely accepted concept in planetary science. If the escape velocity (the speed required for an object to escape the gravitational pull of a planet) is at least six times the average molecular speed at a given temperature, then molecules in the atmosphere can achieve that speed and escape into space.

Question 2

Our Moon is in a 1:1 synch, with a lunar rotation equaling an Earth year.

Accepted Answer

The Moon's rotation and orbit around Earth are in a 1:1 synch, which means we always see the same side of the Moon facing us. However, the Moon's rotation doesn't equal an Earth year, it only takes about 27.3 days to complete one rotation. The Moon's rotation is actually in a 1:1 synch with its orbit around Earth, which is why we always see the same side of the Moon facing us. The Moon's rotation period is about 29.5 Earth days, not a full year.

Question 3

Rilles on the Moon are due to volcanism, not impacts.

Accepted Answer

Rilles on the Moon are formed due to lava flows from volcanic activity, not impact events. Rilles are long, narrow depressions on the Moon's surface that are believed to have formed from ancient volcanic activity, not impacts.

Question 4

Few of the Moon's craters are actually due to volcanism, as was widely thought prior toApollo.

Accepted Answer

Prior to the Apollo missions, it was believed that many of the Moon's craters were formed due to volcanic activity. However, data collected during the missions revealed that most of the craters were actually formed due to impacts from asteroids and comets.

Question 5

For Mercury, the tidal stress of the Sun is much greater at aphelion than at perihelion.

Accepted Answer

Tidal stress is greater at perihelion because tidal forces increase as the distance between two objects decreases, and Mercury is closest to the Sun at perihelion.

Question 6

Mercury and the Earth have about the same average density, but Mercury's core is muchlarger, compared to the size of the body.

Accepted Answer

Mercury's core makes up about 85% of the planet's radius, while Earth's core is only about 55% of its radius. This means that Mercury's core is proportionally much larger compared to the size of the entire planet. Mercury's core makes up about 75% of its radius, while the Earth's core only makes up about 55% of its radius. This means that Mercury's core is proportionally larger compared to the size of the planet than the Earth's core.

Question 7

Ice has been detected near the poles of both the Moon and Mercury.

Accepted Answer

Yes, ice has been detected near the poles of both the Moon and Mercury through various missions and observations. Water ice has been detected on both the Moon and Mercury near their poles. The ice is thought to have been brought to the Moon and Mercury by comets or asteroids and then deposited in the colder regions near their poles.

Question 8

Mercury's rotation and revolution are an example of a 3:2 resonance.

Accepted Answer

Mercury rotates three times on its axis for every two revolutions around the sun, creating a 3:2 resonance. Mercury's rotation (its day) takes 58.6 Earth days, while its revolution (its year) takes 88 Earth days. This ratio of 3:2 means that for every 3 rotations, Mercury completes 2 revolutions around the Sun. This is known as a 3:2 resonance.

Question 9

The most recent features on the Moon's surface are the bright rayed craters like Copernicus,sitting atop the older mare flows.

Accepted Answer

This statement is true. The bright rayed craters like Copernicus are some of the most recent geological features on the Moon's surface, and they sit on top of the older mare flows. This statement is true.

Question 10

The scarps on Mercury are extremely similar to the cratered lunar highlands in appearance.

Accepted Answer

The scarps on Mercury are actually large cliffs resulting from the planet's crust shrinking as it cooled, rather than being similar to the cratered lunar highlands which are primarily formed from impact events.

Question 11

Caloris is well named, for at every perihelion, it faces the Sun directly.

Accepted Answer

Caloris is a large crater on the planet Mercury, and it is located very close to the planet's equator. At every perihelion, which is when Mercury is closest to the Sun in its orbit, Caloris does indeed face the Sun directly. Caloris is a large crater on the planet Mercury, and its location on the planet is such that during every perihelion (the point in Mercury's orbit when it is closest to the Sun), Caloris faces the Sun directly. Therefore, the statement is true.

Question 12

Relative to the size of the planet, Mercury has the largest core of any planet.

Accepted Answer

Mercury's core makes up about 85% of its total volume, which is much larger proportionally than any other planet in our solar system. Mercury is a small planet with a diameter of only 4,879 km, but its core makes up about 85% of its volume, making it proportionally much larger than the cores of other planets in our solar system.

Question 13

Mercury has the widest variation in surface temperatures between night and day of any planetin the solar system.

Accepted Answer

Mercury's lack of atmosphere means that there is no insulation against the extreme heat of the Sun during the day or the extreme cold in the night. This leads to a temperature variation of up to 600 degrees Celsius (1,100 degrees Fahrenheit) between the hottest and coldest parts of the planet. Due to its lack of atmosphere and slow rotation, Mercury experiences extreme temperature differences between its scorching hot daytime side (over 800 degrees Fahrenheit) and its freezing cold nighttime side (below -290 degrees Fahrenheit).

Question 14

The orbit of Mercury is more elliptical than that of any other terrestrial planet.

Accepted Answer

Mercury's orbit has the highest eccentricity among the terrestrial planets, meaning it is the most elongated or stretched-out, making it more elliptical than any other terrestrial planet. This is true. Mercury has the most elliptical orbit of all the terrestrial planets, meaning that its distance from the sun varies significantly throughout its orbit. This eccentricity is due in part to the gravitational influence of the other planets in the solar system.

Question 15

Two Mercury years are the same length as three Mercury sidereal days.

Accepted Answer

One Mercury year is 88 Earth days and one Mercury sidereal day is 59 Earth days. Therefore, two Mercury years are 176 Earth days and three Mercury sidereal days are 177 Earth days, making them approximately the same length.

Question 16

Ice is widely observed in the dark floors of many craters all over the surface of the Moon.

Accepted Answer

Ice on the Moon is primarily found in permanently shadowed regions near the lunar poles, not widely across the surface or in many craters.

Question 17

The lunar mare radioactively date back to 4.6 billion years, at the origin of the Moon, hencetheir dark color due to this aging.

Accepted Answer

The lunar mare are geologically younger than the highlands, dating back to about 3.1 to 3.8 billion years, and their dark color is due to the basaltic lava that filled the basins, not aging.

Question 18

In our solar system, scarps are only found on Mercury.

Accepted Answer

Scarps, or cliffs, are found on various bodies within our solar system, including Mercury, the Moon, and Mars, indicating tectonic activities or impacts rather than being exclusive to Mercury.

Question 19

The high eccentricity of Mercury's orbit probably has nothing to do with Mercury's 3:2 synchof rotation and revolution.

Accepted Answer

The high eccentricity of Mercury's orbit is closely related to its 3:2 spin-orbit resonance, where Mercury rotates three times on its axis for every two orbits it completes around the Sun. This resonance is a stable configuration that likely resulted from tidal interactions between Mercury and the Sun, influenced by the planet's elliptical orbit.

Question 20

Mercury has "weird terrain" directly opposite its huge Caloris Impact Basin.

Accepted Answer

This is true. The area opposite the Caloris Basin is known as the "Weird Terrain" due to its unique and complex geological features. It is believed to have been formed by the shockwaves from the impact that created the Caloris Basin. This is true. The terrain on the opposite side of Caloris is characterized by a jumbled, chaotic landscape with a mixture of hills, valleys, and plains. This is thought to be the result of shock waves from the impact that created Caloris being focused and intensified on the opposite side of the planet.

Quiz 8: The Moon and Mercury: Scorched and Battered Worlds