Exam 1 Quiz Review

Which of the following are true about planetary accretion? (Select all that apply.)

- As these particles accreted, the planets became hot as kinetic energy was converted to thermal energy. - The planets grew larger and larger via repeated impact. - The planets became internally differentiated to different degrees. - The particles that accreted to form the planets were in orbit around the Sun. small particles that are orbiting the Sun collide into one another creating particles that get larger with each collision. Also during collision, the particles get hotter as kinetic energy is changed to thermal energy (think of rubbing your hands together). The thermal energy can almost completely melt the accreted material allowing the dense material (iron) to settle to the bodies center.

The inner planets ______________________.

- have about the same composition as the outer planets - have about the same size as the outer planets - all have orbiting systems of rings - all have several moons ALL OF THE ABOVE ARE INCORRECT The outer planets are ice-hydrogen-helium mixtures, larger than the inner planets, and have rings and moons. They contrast with the inner planets in each of these aspects.

Most asteroids are probably in which size range?

0 to 10 km across Even though asteroids can get up to 1000 km in diameter, most are very small and are below 10 km wide.

What is the size range of asteroids?

0 to 1000 km across Asteroids can be very small and get up to 1000 km in diameter.

Condensation in the solar nebula and accretion of planets is thought to have occurred about how many years ago?

4,500,000,000 y Ages from meteorites suggest condensation occurred 4.5 billion years ago.

Consider the interior structure of a planet. How is a lithosphere different from a crust?

A lithosphere is a mechanical subdivision, and crust is a compositional term. The lithosphere is a mechanical subdivision (it is all solid). The crust is a compositional term (it is basaltic, in most cases).

Consider two planets that are the same age. Which one will have the thicker lithosphere?

A small rocky planet The thermal evolution of planets is only seen in the solid, silicate-rich terrestrial planets. As a planet cools its lithospheric thickness increases, since small planets cool faster than large planets a smaller planet will have a thicker lithosphere.

According to our best modern day evidence, how long ago was the Big Bang?

About 14 billion years ago

What is the age of most meteorites that fall to Earth?

Almost all have ages of about 4.6 billion years. Most meteorites are very old (4.6 billion years ago) because most small, really old material never accreted to a major planet.

Why is there a density difference between Vesta and Ceres? (Select all that apply.)

Because Vesta is rich in silicates and metals. Because Ceres has an outer shell of water ice. The differences in planetary bodies are always a result of what they are made of. The more silicates and metal the more dense the planetary body will be. The more ice, the less dense.

Why do the inner planets lack thick atmospheres of hydrogen and helium?

Because they are too small to have retained such gases. Helium and hydrogen were the most common elements present in the Solar Nebula. They are not present on the terrestrial planets because the inner planets were not large enough to have a enough gravity to hold onto these non-dense elements.

How did the giant outer planets obtain their thick atmospheres?

By collapse of nebular gas onto a protoplanet's icy core. The "cores" of the giant planets grew large enough to have enough gravity to hold onto the light elements in the Solar Nebula. There was not degassing, or picking up gas by sweeping around the Solar System, or volatiles condensing onto the planet (because the nebula was already cold at this location.

The Moon's highland crust consists largely of plagioclase feldspar. Since no magma has that composition, how was plagioclase concentrated in the crust?

By flotation of plagioclase feldspar in a magma ocean. Plagioclase is less dense than mafic magma allowing plagioclase to float to the top of a magma ocean.

How did Earth's atmosphere form?

By gaseous exhalations from rocks deep inside. Earth was not large enough to trap gaseous elements in the Solar Nebula like the outer planets were. Instead, the volatiles in Earth were released from the hot interior.

Which objects have orbits that take them the farthest from the Sun in our solar system?

Comets Some comets have orbital periods of hundreds of thousands of years. The group of comets that occupies the outermost limits of the solar system is called the Oort cloud.

sort the lunar time periods chronologically by placing the youngest period on top and the oldest on bottom.

Copernican Eratosthenian Imbrian Nectarian

What is the best explanation for this dome shaped mound on Ceres?

Cryovolcanism (ice volcano). The morphology looks similar to volcanoes seen on Earth.

Why are asteroids closer to Jupiter so much darker than those near Mars?

Dark carbonaceous materials are common on the asteroids near Jupiter. Asteroids closer to Jupiter are farther from the Sun and have more carbonaceous material.

How are elements heavier than iron produced?

During a supernova explosion Only elements up to iron are made within stars. All heavier elements are created during the intense event of a supernova.

Which is true about our current understanding of extrasolar planets (exoplanets)?

Exoplanets are common and found around many different types of stars. Because stars condense out of a lot of material planets form around many stars, just like our Solar System. Recently, scientists have been able to discover many exoplanets around many stars.

Where did the water in Earth's hydrosphere come from?

From the volatiles released by volcanoes. Water was trapped within the materials that created the Earth. As these materials heated up, the volatile water escaped from the rock and was released on the surface via volcanoes.

Put the following stages in the evolution of a medium-sized star in the correct time order, placing the first stage on the top and the last stage on the bottom. Don't use those that don't apply to a medium-sized star.

Gas & Dust Protostar Main Sequence Star Red Giant Planetary Nebula Medium stars condense into a protostar out of cosmic gas and dust. As the protostar gathers more debris it becomes a main sequence star. Near the end of its life the star will grow into a red giant, and finally the outer layers will be shed, creating a planetary nebula. Supernovas and black holes only form from large stars.

Examine this photograph of the nearside of the moon. How can you tell that Eratosthenes is younger than Imbrium Basin? (Select all that apply.)

Imbrium is buried by smooth lava plains, but Eratosthenes is not. Eratosthenes formed on the rim of Imbrium. Eratosthenes being on top of Imbrium's rim and lava flows shows it is younger.

What geologic process is most common on asteroids?

Impact cratering Asteroids are very small and therefore do not have internal heat to produce volcanic or tectonic activity, nor do they have atmospheres and so cannot have erosion of water or air. However, they have undergone (and are still undergoing) cratering.

Think about the process of planetary accretion. Which statement best describes our current ideas about the rate of impact cratering in the inner solar system?

Initially, the rate declined smoothly, but there was a later episode of heavy bombardment followed by resumption of the decline. The impacted surface of the Moon, as well as modelling, show the impact frequency was high at the beginning of the Solar System. With time frequency decreased (because there was not as much material) until the orbits of the gas giants changed sending a high amount of material into the Solar System causing a spike in the frequency. Since the Late Heavy Bombardment the frequency has declined greatly.

Which is true about iron meteorites?

Iron meteorites formed during the internal differentiation of small asteroids. The best way to get high concentration of iron is differentiation of planetary bodies. So these meteorites must have settled to the core of asteroids that were then broken up by a large impact.

Examine this photograph of the nearside of the moon. What shows that the crater Copernicus is younger than Eratosthenes? (Select all that apply.)

It has fresh rays of impact ejecta radiating from it. The rays from Copernicus cross over Eratosthenes crater. Copernicus' rays cut across Eratosthenes, and Copernicus' ejecta has not been degraded like the other crater.

A giant molecular cloud is best described by which statement?

It is a cool mass of gas and dust that can be light years across. A molecular cloud is a grouping of cool gas and dust. Not to be confused with a planetary nebula that forms from the death of a medium sized star.

Why is the present day Moon less dynamic than the planet Earth?

Its lithosphere is thick. It cooled quickly because of its small size. It has no liquids flowing across its surface. Having no atmosphere or fluids, and having cooled quickly forming a thick lithosphere, the Moon is now geologically dead with no geologic processes occurring on it besides the irregularly time impacts.

Which is true about the most common volcanic rocks found on the Moon?

Lunar volcanic rocks are similar to the most common volcanic rocks on asteroids and other terrestrial planets. Low viscosity basalt is the most common igneous rock on the terrestrial bodies and form lava flow channels, flows, and shield volcanoes.

Which kind of stars have the longest lifetimes (~10 billion years)?

Medium-sized stars like our Sun The larger the star, the faster the star uses its fuel.

Which is the correct sequence of planets, based on increasing average radius of their orbits?

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto My Very Educated Mother Just Served Us Nine Pizzas.

What are the major differences between a moon and a planet? (Select all that apply.)

Moons revolve around a Sun-orbiting planet. Planets revolve around the Sun. A few moons are actually bigger than Pluto and Mercury. By definition, moons (natural satellites) don't orbit the Sun but instead revolve around another planetary body. Some asteroids even have moons.

What is the most likely cause of the linear ridges and grooves near equator of Vesta?

Near disruption by a large impact

Do the principles of superposition and cross cutting relations tell us how old a particular crater or surface is in number of years (the absolute age)?

No, it can only show relative dates. For example, it is younger than the surface it impacted on .

What is a major difference between planets and stars? (Select all that apply.)

Planets are much smaller in diameter than the stars around which they revolve Planets do not generate energy through nuclear fusion. Planets have rings and systems of orbiting moons and some planets (the outer planets) lack solid surfaces.

What is the basis for our understanding of the absolute time scale of the Moon?

Rock samples brought back from the Moon have been dated using radiometric techniques to give their absolute ages. Radiometric ages are determined from radioactive elements in rocks.

Which describes the Moon's history better?

The Moon first expanded slightly because of heating and has since been contracting. When refractory materials are hot and liquid they take up more space than the solid equivalent. Since the Moon started out mostly molten it initially expanded. But as most of the magma solidified it contracted as the solid version of magma is more dense.

What is the major difference between the composition of the Moon and Earth?

The Moon is poorer in water than Earth. The Moon has less water than the Earth. This is seen in the absence of oceans, water ice, and explosive eruptions. We know the Moon is poorer in iron because it has a much smaller core than the Earth.

Which of the following statements about the Moon's core are correct? (Select all that apply.)

The Moon's core is probably made of iron. The Moon's core was once molten and convected to make a magnetic field. Like the terrestrial planets, the Moon's core is most likely made of iron. And once had to convect for there to evidence for a past magnetic field in the rocks. Seismology shows the core of the Moon is very small, but does show the Moon is differentiated.

Which of the following is involved in collisional accretion?

The aggregation of planetismals when they impact one another. Collisional accretion is the gradual growing of material by colliding. This process does not have to do with materials changing their state from gas to solid (condensation), a nebula becoming smaller by collapse, or the gravitational constant changing (it is constant for a reason).

Which of the images below is the oldest surface of the Moon?

The amount of craters correlates with surface age. The more craters the older the surface.

Which of the following are the characteristics of the asteroid belt? (Select all that apply.)

The asteroids mark the transition from the rocky terrestrial planets to the outer planets. Some asteroids appear to be rocky; some seem covered with lava; others seem to be metallic; and yet others may have water ice. Many meteorites that fall on Earth come from the asteroid belt. The largest asteroid Ceres is almost 1,000 km across. The asteroids are between Mars and Jupiter and have a wide array of compositions.

What process formed sinuous valleys?

The eruption of lava flows. Sinuous valleys are made by the erosion of regolith by lava flows. The erosion is both mechanical (picks up particles) and thermal (melts particles). Erosion by water (or from melting ground ice) does not produce features with this morphology. They produce dendritic patterns. Lithospheric faulting produces straight lines, not sinuous.

Which of these is evidence for planetary accretion?

The heavily cratered surfaces of the Moon and other planetary bodies. As we know, craters are formed by a body colliding with the surface of a planetary body. Atmospheres are not controlled by collision, but volatile content of the planet. The rings of Saturn are objects in orbit around Saturn, and therefore are not collisional. And water indicates Earth has water.

The spin axes of some planets are tilted relative to the plane in which most orbit. What could have caused this?

The impact of a large object late in the history of accretion changed the spin. Just like someone being punched in the face, a planet being hit hard by a large object will move and become tilted. As a body accretes, the gravity makes the body spherical so one side cannot have more material than another. Other stars are too far away to make a near pass and capture a planet. if a planets spin axis changed with time, all of the planets would be tilted the same amount.

What sets the composition of the moons of the outer planets apart from the inner planets?

The moons of the outer planets generally have lower densities. The moons of the outer planets are too small to retain atmospheres of hydrogen and helium and are dominantly water ice rather than nitrogen ice, which is only stable in the far outer reaches of the solar system.

How old are the oldest rocks found so far on the Moon?

The oldest rocks found on the Moon so far are about 4.5 billion years old.

Which of the following best describes the orbital evolution of the planets in our solar system according to the Nice Model?

The orbits of the outer planets changed significantly about 3.9 billion years ago as Uranus and Neptune moved outward from the Sun. As mentioned above, the orbits of the gas giants changed dramatically 3.9 billion years ago. The orbits extended farther form the Sun (especially Neptune and Uranus) and the orbits of Neptune and Uranus switched. The inner planets orbits remained unaffected.

Why are the rocks found at the surface of a planet, say Mercury, so different in elemental composition from the meteoritic material from which it formed?

The planet differentiated after accretion. Initially all the planets were homogeneous and accreted from materials of the same composition as meteorites. However, density differences of the various elements allowed segregation. Layers of varying composition formed, with each layer being a different composition than its average composition.

When did the planets form?

The planets formed about the same time as the Sun in a relatively short period of time only a few million years long. Because of the amount of impact craters on many of the planetary bodies, and radiogenic dating we know the planets must be around 4.5 billion years old, the same age as the chondritic meteorites. These data suggest the planets formed concurrently with the Sun and completed forming relatively quickly.

Why do the planets have different densities?

The planets have different mixtures of ice, silicates, iron, and gas Planets have different amounts of each element. Those planets with more dense elements will be denser than those without.

What do the absolute ages of lunar rocks tell us about changes in the rate of impact cratering during the Moon's history?

The rate of impact on the Moon has declined dramatically with time so that modern impact rates are much lower than they once were.

Why are the inner planets depleted (poor) in volatile elements?

Their constituents condensed at higher temperatures The inner planets are enriched in refractory elements and depleted in volatile elements because these planets formed near the Sun where it was too hot for volatile elements to condense, but was not too hot for condensation of refractory elements.

Why do impact craters make good geologic time indicators? (Select all that apply.)

Their features change with time as a result of degradation. They are produced instantaneously. They are laterally extensive (they cover large areas). Impact craters are fantastic for determining relative time since they can cover large areas, the degrade with time, and are produced quickly.

Which of the following are characteristics of the orbits of the objects that accrete to make planets? (Select all that apply.)

Their orbits form a flattened disk shape. They orbit in the equatorial plane (ecliptic) of the star. All of the planets orbits are in the same plane as the Sun's equator (near enough). The orbits also form a disk shape. Therefore, the orbits cannot be spherical or tilted ninety degrees to the ecliptic (plane of the Sun's equator).

Which of the following is correct about the nebulas we see in the sky today? (Select all that apply.)

They are concentrations of interstellar gas and dust Many are the birth grounds of stars. Some form when stars explode. The nebulas we see today are concentrations of gas and dust that give rise to new stars. Some of these nebulas formed by supernovas.

Which statement is true for the outer planets of our solar system?

They are largely made of hydrogen and helium. The giant outer planets are not large enough to sustain nuclear fusion like stars, but they are made of similar materials—hydrogen and helium. They have no solid surfaces and they commonly have rings.

Why are chondritic meteorites so important?

They are undifferentiated, and preserve evidence about the age and nature of condensation in the ancient solar nebula. Chondrites are thought to be the oldest material in the Solar System and show the primeval composition of the solar nebula.

What properties of the atmophile elements (hydrogen, helium, carbon, nitrogen, oxygen) allow them to generate atmospheres?

They are volatile elements. They form molecules with low densities For an element to be in an atmosphere it must be volatile (condenses at cold temperatures) and low density (so it can rise above the planet's surface).

Which of the following are correct about red giant stars? (Select all that apply.)

They form as a star expands and the surface cools. They evolve from medium-sized stars. Red giants form by expansion and cooling of the surface of a medium sized star.

What were the most common solids that condensed from the solar nebular gases?

They were water ice. Water ice is the most common condensate in the Solar System. It may not be the most common in the inner Solar System, but the asteroid belt and beyond contains a vast amount of water ice.

Which of the following objects is most like Earth in size and composition?

Venus Venus is nearly the same diameter and composition to Earth. Neptune is large and compositionally very different, and the others are rocky like Earth, but significantly smaller.

Which of the following is most accurate about volcanic activity on the asteroids?

Volcanism occurred anciently on at least some asteroids. Because of the small sizes, volcanism would have occurred on asteroids long ago.

How will the Sun's life probably end?

With the formation of a planetary nebula. Our Sun is too small to go out in a giant explosion or form a block hole. Instead it will die a gentle death of its outer layers floating into space to create a planetary nebula.

Important sources of planetary heat include

accretion core formation tidal heating decay of radioactive elements

Some stony-iron meteorites appear to have ______________________.

been formed at the core-mantle boundary of an asteroid The mantle of planets is made of silicate material (such as olivines) while the core is made of iron. So it is likely the stony-iron meteorites are from the transition zone of mantle to core.

At one time the Moon may have _______________.

been volcanically active The Moon has no evidence of an atmosphere or hydrologic system. However, there are many lava flows and channels that show the Moon was volcanically active.

Large planetary bodies failed to accrete in some parts of the solar system and did not sweep their neighborhoods clear of debris. Select the two most prominent zones of this "debris."

between Mars and Jupiter beyond Neptune Failure of large planetary bodies forming would leave behind a lot of material, smaller than planets, that did not accrete to form a planet. The two main areas of high amounts of small bodies are the asteroid belt (between Mars and Jupiter) and the Kuiper Belt (past the orbit of Neptune).

The surface of the Moon can be divided into two general terrains. What are they?

bright and dark terrains old and young terrains high and low terrains the maria and the terrae The surface of the Moon is made up of two terrains. The maria, which is low, young, and dark. And the highlands terrae, which is high, old, and bright.

The lunar highlands, or terrae, are typified by ___________.

closely spaced impact craters There are numerous craters that can be seen in the highlands of any planet wide image of the Moon.

Many supernovas are the result of _____________________.

collapse of a star with multiple burning shells Supernovas occur in nuclear fusion slows down tremendously in large stars. The star then collapses in on itself and ignites any unburned fuel causing a large explosion.

Most of the mass of the solar nebula resided in materials which

did not condense to form solids Most of the material in the Solar System (more than 99%) resides in the Sun and therefore, did not condense to form any solids.

Which of the following ways can a planet's atmosphere lose gas?

escape to space formation of limestone or carbonate materials formation of polar ices

Craters with central peaks generally ______________.

have terraced walls Central peaks occur in large craters on the Moon from impact. The have terraced walls on the side.

Which list is made of very volatile materials?

helium (He), argon (Ar), ammonia (NH3), and methane (CH4) Helium, argon, methane, and ammonia are very volatile elements and only condense at extremely cold temperatures.

About how old are the lunar maria?

hey range in age from about 4.0 billion years old to at least 2.5 billion years old.

The T-Tauri phase of a star's history ______________________.

is typified by extreme fluctuations in energy and a strong magnetic field The T-tauri stage occurs near the end of a stars formation. During the T-tauri stage, the star gives up huge amounts of energy and has a strong magnetic field. The energy may clear away some of the loose debris surrounding the star, but it is not strong enough to strip away the atmosphere of formed planets

Which of the following types of energy is mostly responsible for crater generation?

kinetic energy The motion of the impactor creates the crater. radiogenic, potential, and thermal energy do not cause the holes.

Landforms produced by lunar volcanism include which of the following? (Select all that apply.)

lava flows low shield volcanoes lava channels Lava flows, channels, and shield volcanoes are common volcanic landforms on the Moon. Stratovolcanoes and ash flow calderas are not seen because the Moon does not have enough internal volatiles to produce these landforms.

Which of the following is not a mechanism of heat transport.

magnetism Heat can be convected (like boiling water), conducted (touching a stove), and radiated (the Sun shining). Magnetism is the attraction and repulsion between objects (magnets).

In general , large planets cool _____________________.

more slowly than small planets of similar compositions Large planets cool more slowly than large planets because they have a smaller surface area/mass ratio. As we learned in a previous lesson, core formation adds heat to the planetary body. The formation of a lithosphere is a result of cooling, as a planet cools its lithosphere thickens. Therefore a planet cannot cool before a lithosphere forms.

Water ice is __________________________.

most abundant on the moons of the outer planets Water ice is stable and common on the moons of the outer planets and into the Kuiper belt. It is unstable in the near vacuum of the inner solar system because the temperature is too high.

What is the principal method of light element (up to iron, atomic number 26) production?

nuclear fusion Elements up to iron are constructed by nuclear fusion within stars.

The most important mineral in the upper mantle of the Moon is _______.

olivine Olivine is a common mineral in all of the terrestrial planets mantle.

Which of the following is a feature formed by impact on the Moon?

overturned flap on the crater rim radiating arms of ejecta around the crater terraces on the side of the crater

The most basic subatomic particles include which of the following? (Select all that apply.)

protons, neutrons, electrons Protons, neutrons, and electrons are the basic subatomic particles that compose the elements. Ions are elements that has a positive or negative charge (lost or gained electrons). Isotopes are elements with varying number of neutrons.

A "star" that shines, but not as a result of nuclear reactions, is called a __________.

protostar Protostars shine because of the heat produced by friction as debris collapses onto the forming star. The T-tauri stage of a star begins with the onset of nuclear fusion. A nebula shines because of surrounding stars and planetismals do not shine at all.

Which of the following is not a feature formed by impact on the Moon?

sinuous rilles Sinuous rilles are volcanic landforms, they do not form by impact like the other listed features.

The energy of crater formation is expended in which of the following ways? Mark all that are correct.

slumping to create terraces heat seismic (earthquake) waves fracturing of the bedrock Impacts establish shock (seismic) waves that pass through the interior, they can break up rock and cause slumping, and even melt (or vaporise) rock.

Most meteorites that fall to Earth are of which type?

stony meteorites Chondrites are thought to be the oldest material in the Solar System and show the primeval composition of the solar nebula. Stony meteorites are common because they are from the surface of planetary bodies, and are therefore easy to knock off the surface.

Important sources of planetary heat include all of the following except _______________.

the Big Bang Planetary heat comes from many sources that have to do with the formation, differentiation, and gravitational interactions. The Big Bang does not fall into these categories and occurred so long ago the heat is not an important factor in planets.

What is the weak layer within a terrestrial planet that behaves like a viscous (flowing) fluid?

the asthenosphere The asthenosphere is the partially molten, and viscously behaving layer in a terrestrial planet. The crust is the upper most section of a terrestrial planet that is made of basaltic or felsic composition. The lithosphere is a subdivision of a planet that consists of the crust and solid mantle. The mantle is a section ultramafic rock in a terrestrial body.

What is the evidence the highlands of the Moon are older than the low lands (maria)?

the highlands have abundant impact craters. The frequency of impact craters on a landform is the best way to determine if it is old or not. The highlands have many more impact craters than the maria suggesting the highlands are older.

The presently favored theory for the origin of the Moon calls for which of the following scenarios?

the impact of a large body into the Earth. The low density and composition (lack of water and other volatile elements) of the Moon suggests the Moon formed from a collision between a Mars-sized impactor and the Earth. This impact sent material out in orbit around the Earth and it accreted into the Moon.

Which of the following is least important for the appearance of an impact crater developed on the surface of a planet?

the presence of a magnetic field The size of the impactor and nature of surface materials determine the physical aspects of an impact crater. An atmosphere would produce friction slowing down and breaking the impactor. However, a meteorite can travel through a magnetic field as if it was not there.

Which of the following is not a way that a planet's atmosphere can lose gas?

the process of outgassing Outgassing is the processes of moving volatiles from the interior to above the surface. This process introduces gas into the atmosphere, it does not take away gas.

What is one evidence suggesting that SNC meteorites came from Mars?

their young ages Young meteorites must have undergone differentiated processes to have a young formation age. Only planets are large enough to have still had these processes going on recently.

Examples of highly refractory materials are ____________________________.

tungsten (W), osmium (Os), and zirconium (Zr) Refractory elements are those that condense at high temperatures. Volatile elements condense at low temperatures.

Mare basalts are characteristically _________________________.

very fluid The low topography of the mare basalts shows the lava was very fluid (similar to motor oil). We know the mare is not older than the highlands because the mare has less craters. Since there are no explosive landforms we know they basalts did not have water. The crust is never thicker than the lithosphere.