Chapter 8

bounce lasers off the retroreflectors left on the surface by the Apollo landings.

it never gets more than 28 degrees from the Sun's glare.

true

it has no true atmosphere to moderate temperatures over the globe.

Neither body has a permanent true atmosphere.

rotation rate

extreme variations in its surface temperature.

true

almost entirely on Earth side, where the crust was thinner.

the craters sitting atop the mare.

3.9-3.2 billion years old, forming after most of the bombardment was over.

just under 4 billion years ago.

false

The maria and highlands have distinctive appearances. The maria are dark and smooth, while the highlands are light-colored and rough.

-low elevations -flat regions -few craters

-mountainous regions -high elevations -highly cratered

radar beams

Like our Moon, Mercury does not rotate at all, keeping the same side facing the Sun.

-the planet's very eccentric orbit -the planet's closeness to the Sun -the planet's high density -tidal torques operating on the planet -All of the above are factors.

they are equal

true

true

false

the rain of micrometeorites chewing up the regolith.

they range from 4.6-4.4 billion years old, on average.

rilles associated with lava flows accompanying the mare formation

Clementine and Lunar Prospector.

true

true

true

moon

clusters of depressions found near the center of impact craters.

-the lunar mare are darker than Mercury's intercrater plains. -Mercury does not always keep the same face toward the Sun, while the Moon does have the Earthside always facing us. -Mercury has "weird terrain" opposite its huge Caloris Basin. -Mercury has striking lobate scarps due to the shrinking of its core. -All of the above are correct.

the lunar far side

Caloris.

true

true

the seismographs left these by the Apollo astronauts.

It is 1/100th as strong as ours, but does deflect the solar wind to some degree.

The dynamo theory predicted that Mercury was spinning too slowly for one.

dynamo action, like the Earth's magnetic field.

true

false

Impact Theory

the retrograde orbit and large orbital inclination of Neptune's moon Triton

spin-off

coformation (or sister) theory

capture theory

impact theory

The moon and earth should have very similar compositions

-The moon and the earth should have very different compositions -mathematical models would need to predict that the capture of a moon-sized satellite would be likely in Earth's early history

-Earth and the Moon should have similar mantles and dissimilar cores. -Computer simulations should predict that a collision between Earth and a Mars-sized object would produce a Moon-sized satellite with a stable orbit.

-Earth has a large iron core, but the Moon does not. -The mantles of Earth and the Moon have similar compositions. -Computer simulations predict that a collision between Earth and a Mars-sized object would produce a Moon-sized satellite with a stable orbit.

According to the impact theory, a glancing collision between a Mars-sized object and Earth led to the formation of the Moon. The iron core of Earth had formed before this collision, leading to the similarity between the composition of the Moon and Earth's mantle. After the collision, any iron core of the Mars-sized object would have been left behind on Earth and eventually merged with Earth's core. The Moon then formed out of the debris thrown into space by the collision.

they are older than the smoother maria.

dense Mercury had an iron core that shrank, creating the lobate scarps.

the less dense and smaller Moon did not have as much radioactivity as the larger Earth in its core.

FMoon/FEarth = 0.2

Mmin = 4.2×1023 kg