astronomy quiz answers L1-4

Mercury has a large impact basin called Caloris. When did it form?

3.8 byrs ago

The Hellas Basin is a large impact basin on Mars. When did it form?

3.8 byrs ago

George Darwin (son of Charles Darwin) predicted that the Moon is receding from the Earth and recent measurements confirm that he was correct! How fast is that recession and what is causing it?

3.8cm/yr; tidal drag

According to Kepler's third law, a planet with a period of 8 years would have a corresponding semi-major axis of ___ AU.

4

the age of the solar system is about

4.5 byrs

the sun contains what percentage of mass in the solar system?

99%

The Spirit landing site was chosen because it looked like a classic Lacustrine environment. In otherwords, the landing site looked like what?

A dry lake bed

Worlds of the Solar System are believed to have formed via the process of

Accretion

Why do we believe a world with a density of 3.4 g/cm3 composed of mostly rock with a little iron?

Because rock is 3 g/cc and this worlds density is just a bit larger than that. That means there's a little of something more dense within the world, like iron.

The huge dome-like coronae features on the surface of Venus are believed to be a result of what process?

Blob tectonics

In lecture, you were told that finding either Hematite or Goethite at a site indicated that liquid water was once present there. Why do these minerals point to the presence of liquid water in the past at the sites where they were found?

Both minerals form in warm, wet environments

The atmosphere of Mars...

does not interact strongly with the surface

The atmosphere of Venus...

does not interact strongly with the surface

The fact that most salts and seasonal flows on Mars are found in the heavily-cratered southern Highlands implies that liquid water

existed on the surface in the distant past

The symbol ∝ means

proportional to

Mauna Kea on the big island of Hawaii and Olympus Mons on Mars are both

shield volcanoes

What appears to be the most common type of volcano that you know of in the Solar System?

shield volcanoes

The Viking Landers were sent to Mars to look for evidence of

simple, single-celled life

mare regions on the moon are defined by

small amount of craters and low albedo

The Hematite that was detected from space at the Opportunity rover landing site was found to be in the form of

small spheres scattered all over the landing area

Water in the atmosphere of Venus is destroyed mainly by interactions with:

sunlight

If you were to double the size of the Earth (increase the radius by a factor of 2) and quadruple the mass of the Earth (increase the mass by a factor of 4), how much would it change the gravity (Fg) on the Earth?

Fg would be the same

What caused the permanent depletion of carbon dioxide from Mars' atmosphere?

Geologic activity died off and carbonate rocks were not "recycled" by volcanoes

Which of the four (4) theories proposed for the formation of the Moon appears to be the most probable explanation for the formation of the Earth's Moon?

Giant impact

Small variations in the Earth's obliquity over 41,000 years brings on what event?

Ice ages

The Phoenix Lander also found Perchlorate at its landing site near the north pole of Mars. What is a significant property of Perchlorate?

It acts like anti-freeze, allowing water to exist briefly as a liquid on the surface

Geologic activity on both Mercury and the Moon ended around the same time (~3.5 Byrs ago). Geologic activity ended on Mars much later (~0.5 Byrs ago). Why did geologic activity on Mercury and the Moon end so much sooner than geologic activity on Mars?

Mercury and the Moon are both smaller than Mars.

Mercury has strange features on it's surface called Scarps. Why do we see these features on the surface of Mercury and not on the surface of the Moon?

Mercury has a massive iron core, the Moon does not

Which of the following is true? 1. Mercury is in a highly elliptical orbit around the Sun 2. Mercury's geologic activity ended "yesterday". 3. Mercury is smaller than the Moon. 4. Mercury was geologically active in its distant past.

Mercury was geologically active in its distant past.

list the four terrestrial planets

Mercury, Venus, Earth, Mars

The N(10) value in a crater-density plot of a particular surface is related to what property of that surface?

the surface age

The Soviet Venera Landers found the surface at their landing sites on Venus to be composed primarily of ____________________________________.

unweathered basalt

On the Magellan radar images, regions that appeared as light had a _______________________ surface texture

very rough

Viking 1 found evidence of what on the surface of Mars?

wind modification

Most of the craters on both Mercury and the Moon formed ________.

within the first 700 million years after their formation

Olympus Mons is the largest volcano (by far) in the Solar System. What is the main limiting factor in how high you can build Olympus Mons (or any volcano for that matter)?

Surface gravity of the world

The same side of the Moon always faces the Earth. This is a result of a process called ________________ in which the ___________________.

Synchronous Rotation; the time it takes the Moon to orbit the Earth is the same time as it take to make one revolution on its axis.

Why would you think we need the Moon to understand the Earth's very ancient past?

The Earth is geologically active and this has erased most old surfaces

almost all impact craters on Venus are: (list three)

- 10-100 km in diameter - complex impact craters - pristine

Compared to shield volcanoes on Earth, the shield volcanoes on Venus are:

- much broader/wider - the same height

the albedo of asphalt is

0.2

The moment of inertia (K) of a world that is a uniform sphere of material is

0.4

the albedo of a piece of notebook paper is

0.6

The expression (1/4) / (1/2)^2 can be most simplified to

1

The number of small impact craters and impact basins on a crater-density plot of the surface of Venus departs dramatically from what we would expect for a world in the inner Solar System. Why? (two answers)

1. "Recent" geologic activity erased all evidence large impact basins. 2. small impactors burn up in the atmosphere

There are four main gasses released when a rocky surface melts. Two of the four are _______________ & __________________.

1. CO2 2. Nitrogen

What evidence of water did Mars Pathfinder find in Ares Valles? (2 answers)

1. Sedimentary rocks that show a layered structured potentially caused by liquid water 2. Igneous rocks produced by volcanic action (transported possibly by water to Ares Valles)

You learned about four atmospheric sinks currently at work in the Martian atmosphere. Which of the answers below is an atmospheric sink for Mars? (three answers)

1. Solar stripping of molecules in the upper atmosphere 2. Mars' low gravity 3. Impacts driving off molecules from the atmosphere

Mercury's dense iron core is huge relative to its size and the amount of rock the tiny world has. How is this possible? (3 answers)

1. Strong solar winds may have stripped off a large amount of its rocky surface. 2. It may have suffered a collision with a large planetesimal that stripped a large amount of rock from its surface. 3. It formed closest to the Sun where more dense elements existed.

You were presented with a considerable amount of evidence suggesting that liquid water existed on the surface of Mars in the past. What are the main reasons liquid water can not exist on the surface today? (two answers)

1. The atmosphere is too thin 2. the surface is too cold

There are two main processes modifying the surface of Mars today.

1. low level impacts 2. wind

Earth has several efficient sinks for CO2. Two are discussed in detail in the lectures. Which of the following are correct? (two answers)

1. plant life 2. weathering

The oldest rocks found near the rim of an impact crater come from a depth equal to

1/10 the crater diameter

room temperature and pressure are

20 C and 1 ATM

The deepest rock excavated from a 200 m crater would come from a depth of about

20m

The lecture discusses tidal drag in the Earth-Moon system. This drag will eventually result in which of the following scenarios?

Eventually the Earth's rotation will be identical to the Moon's orbital period

Which of the two surfaces in Question 16 (mare or highlands) is younger?

Mare

impact breccia is defined as

Rock composed of fragments of minerals/rock cemented together

The Opportunity rover sampled rocks at the rims of increasingly larger craters on Mars. Why?

Rocks on the rims of craters reveal the ancient history of Mars

Suppose you discovered a new planet in the Solar System. It is a rocky planet, similar to Earth, and is closer to the Sun than Earth (about 0.8 astronomical unit (AU) from the Sun). You want to study its atmosphere; what effect would have most likely affected the atmosphere and what property would be evidence of this effect?

Runaway greenhouse effect; high amounts of CO2 in the atmosphere

We'll talk about plate tectonics more in Lesson Module 5, but you'll notice that we didn't mention the process at all in the lectures. Why did we omit that discussion?

The Moon never had plate tectonics.

Why can we get the absolute ages of the surfaces of both Mercury and Mars by using the surface ages determined from the Moon?

The R-plots for their surfaces are all similar

What does the term obliquity refer to?

The axial (spin axis) tilt of a planet

The Moon is slowly drifting away from the Earth. The lectures discuss how the drift will eventually stop, but the Earth won't actually lose the Moon. Based on your understanding of the gravity equation, why might you suspect this is true?

The distance is increasing so the force between the two worlds is decreasing by R^2 so the force between the two is decreasing exponentially over time.

The Fission Theory is one of the four possible ways the Moon could have formed. How does that theory explain the lack of volatile elements in the Earth-Moon system?

The fission process is a high energy event.

The Moon and the Earth have the same chemical fingerprints. What does this mean?

The isotopic ratios of the Earth and Moon are exactly the same

The Moon is highly differentiated, but it's moment-of-inertia value (K) is nearly 0.4. What does this imply about the Moon?

The materials in its interior are about the same density as the surface materials

What did the discovery of Pristine Highland Rock (Anorthosite) tell us about the Moon?

The moon is highly differentiated

We learned something important about Mars when comparing the chemical analysis of the soil at the Viking lander sites to the soil at the Pathfinder site. What was it?

The soil is the same composition everywhere

What is the most likely reason there is no plate tectonics on Venus today?

There is no water on Venus today.

What did we learn by determining the average age of the large impact basins on the lunar surface?

There was a period of intense impacts of large objects 3.8 Byrs ago

Why do some scientists believe tides are important to early, complex life on Earth?

Tides force marine creatures to interact with the land, bringing complex life to the land.

Why is there almost no temperature difference between Venus's equator and the poles?

Transportation of the solar energy by convection is very effective due to the planet's slow rotation.

What is the order of the planets in terms of atmospheric surface pressure (from highest to lowest pressure)?

Venus > Earth > Mars

In lecture, you were told about a "key ingredient" that makes plate tectonics function efficiently. What was that ingredient?

Water

The two most abundant gasses released by volcanism on worlds in the inner Solar System are _________________ & __________________.

Water (H2O) & Carbon Dioxide (CO2)

Venus' early atmosphere was predominately composed of:

Water Vapor

The Spirit rover found copius amounts of Olivine in the soil samples form Gustav Crater. What does this tell us about the presence of water in the crater?

Water could not have existed in the crater for more than ~100 Myrs

The Clementine mission to the Moon revealed a remarkable find and one that is of utmost importance to future manned missions. What was it?

Water ice

What is the significance of finding the N(10) values and absolute ages of the 6 surfaces that the Apollo astronauts landed on? Select the answer that best addresses the question.

We can use the ages and N(10) values to determine the absolute ages of other surfaces on the Moon by just counting craters.

The Mare on Mercury is ______ and ______.

a different chemical composition than the Mare on the Moon about the same age as the Mare on the Moon

Venus produces heat at

about the same rate as Earth

Apollo 11 landed on a big, flat Mare surface. The astronauts returned rock samples composed primarily of

basalt

The rocks strewn around the Viking 2 lander site appear to be (or are most likely) which type of rock sample?

basalt

Why would you NOT expect to find rocks like anorthosite on a Mare surface?

because anorthosite is a very old rock and mare is a young surface; mare covered that original ancient crust

A world with a density of 5.5 g/cm3 would be composed of

half iron and half rock

The two main surface regions on the Moon are the Lunar Mare and Lunar Highlands. Which surface is more heavily cratered?

highlands

The Phoenix Lander on Mars dug into the soil near its feet and found

ice

What is the most wide spread (common) process shaping the surface of the Moon today?

impact cratering

The moment of inertia (K) of a differentiated world would be _______________ an undifferentiated world?

less than

Much like the variations in obliquity that the Earth experiences, the Moon, too experiences a periodic wobble as it orbits the Earth. This wobble is called

libration

Large worlds remain geologically active longer than small worlds because they have more radioactive "fuel" and they....

lose heat at a slower rate

When UV light dissociates a water molecule in the atmosphere of Venus (breaks the bond between the O atom and the two H atoms), where do the hydrogen atoms go?

lost to space

If some catastrophic event killed all life on Earth tomorrow, which of the following gasses would slowly be lost from Earth's atmosphere?

oxygen