Geology Exam 1

Most asteroids are probably in which size range? A. 0 to 10 km across B. 0 to 100 km across C. 0 to 1000 km across D. 0 to 10,000 km across

A

Using the dropdown boxes below, sort the lunar time periods chronologically by placing the youngest period on top and the oldest on bottom. Imbrian Eratosthenian Nectarian Copernican

Copernican (youngest) Eratosthenian Imbrian Nectarian (oldest)

Condensation in the solar nebula and accretion of planets is thought to have occurred about how many years ago? A. 4,500 y B. 4,500,000 y C. 450,000,000 y D. 4,500,000,000 y

D Ages from meteorites suggest condensation occurred 4.5 billion years ago.

What do the absolute ages of lunar rocks tell us about changes in the rate of impact cratering during the Moon's history? A. The rate of impact on the Moon has declined dramatically with time so that modern impact rates are much lower than they once were. B. The rate of impact on the Moon has increased regularly. C. The rate of impact has been about the same throughout its long history. D. The rate of impact has declined over the first 2 billion years of the Moon's history, but has been increasing ever since.

A

Which of these is evidence for planetary accretion? A. The heavily cratered surfaces of the Moon and other planetary bodies. B. The absence of atmospheres on the Moon and Mercury C. The rings of Saturn. D. The abundance of water on Earth.

A 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.

Why are chondritic meteorites so important? A. They are undifferentiated, and preserve evidence about the age and nature of condensation in the ancient solar nebula. B. They contain a great abundance of metallic grains that can be extracted for a profit. C. Most are thought to have crystallized on Mars. D. Many are remnants of the Big Bang.

A Chondrites are thought to be the oldest material in the Solar System and show the primeval composition of the solar nebula.

Most meteorites that fall to Earth are of which type? A. stony meteorites B. iron meteorites C. stony-iron meteorites D. from the Moon or Mars

A 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.

Why do the inner planets lack thick atmospheres of hydrogen and helium? A. Because they are too small to have retained such gases. B. These elements were not present in the inner part of the solar nebula. C. Because these elements did not condense to form solids. D. Because they are efficiently outgassed from the interior of planets.

A 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.

Which list is made of very volatile materials? A. helium (He), argon (Ar), ammonia (NH3), and methane (CH4) B. iron (Fe), nickel (Ni), and iron sulfide (FeS) C. tungsten (W), osmium (O), and zirconium(Zr) D. sodium (Na), potassium (K), and rubidium (Rb)—the alkalies

A Helium, argon, methane, and ammonia are very volatile elements and only condense at extremely cold temperatures.

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? A. The planet differentiated after accretion. B. Layers of different composition sequentially accreted to the planet. C. Dissolution by water and upward transport of the soluble elements created distinctive outer layer. D. Late stage condensation of mafic silicates from the nebula buried the surface.

A 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.

The spin axes of some planets are tilted relative to the plane in which most orbit. What could have caused this? A. The impact of a large object late in the history of accretion changed the spin. B. More accretion occurred on one side of the planet than on the other and it tipped on its side. C. These planets were probably captured from a passing star. D. With the passage of time, the spin axis of a planet starts to tilt to one side.

A 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.

Most of the mass of the solar nebula resided in materials which A. did not condense to form solids. B. condensed to form ice. C. condensed to form silicate materials. D. condensed to form metals.

A 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 objects have orbits that take them the farthest from the Sun in our solar system? A. Comets B. Asteroids C. Pluto and its moon Charon D. Galilean satellites

A 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.

Which kind of stars have the longest lifetimes (~10 billion years)? A. Medium-sized stars like our Sun. B. Large stars about 10 times larger than the Sun.

A The larger the star, the faster the star uses its fuel.

Consider the interior structure of a planet. How is a lithosphere different from a crust? A. A lithosphere is a mechanical subdivision, and crust is a compositional term. B. A lithosphere is a chemical subdivision, and a crust is a mechanical subdivision. C. A lithosphere is made of less dense rock that floats on the rigid crust. D. A lithosphere is made of dense rock that floats on the rigid crust.

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

The lunar highlands, or terrae, are typified by ___________. A. closely spaced impact craters B. basaltic lava flows C. long anorthositic lava flows D. a multitude of volcanic craters

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

What are the major differences between a moon and a planet? (Select all that apply.) A.Planets revolve around the Sun. B. Moons revolve around a Sun-orbiting planet. C. Moons are smaller than any of the planets. D. Except for Earth's moon, all other moons orbit the Sun between Mars and Jupiter.

A & B 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 a major difference between planets and stars? (Select all that apply.) A. Planets are much smaller in diameter than the stars around which they revolve. B. Planets do not generate energy through nuclear fusion. C. Planets do not have systems of smaller bodies in orbits around them like many stars do. D. Planets have solid surfaces, and stars do not.

A & B Planets have rings and systems of orbiting moons and some planets (the outer planets) lack solid surfaces.

Why is there a density difference between Vesta and Ceres? (Select all that apply.) A. Because Vesta is rich in silicates and metals. B. Because Ceres has an outer shell of water ice. C. Because Ceres is rich in silicates and metals D. Because Vesta has an outer shell of water ice. E. Because Vesta is more strongly fragmented by impact than Ceres is.

A & B 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.

What properties of the atmophile elements (hydrogen, helium, carbon, nitrogen, oxygen) allow them to generate atmospheres? Select all that apply A. They are volatile elements. B. They are refractory elements. C. They form molecules with low densities D. They form molecules with high densities. E. They are all chalcophile elements as well.

A & C 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 characteristics of the orbits of the objects that accrete to make planets? (Select all that apply.) A. Their orbits form a flattened disk shape. B. Their orbits form a spherical zone centered on the star. C. Their orbits define an elliptical zone tilted about 90° to the eliptic. D. They orbit in the equatorial plane (ecliptic) of the star.

A & D 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).

Why do impact craters make good geologic time indicators? (Select all that apply.) A. They are laterally extensive (they cover large areas). B. They are produced instantaneously. C. Their features change with time as a result of degradation.

A, B & C Impact craters are fantastic for determining relative time since they can cover large areas, the degrade with time, and are produced quickly.

Landforms produced by lunar volcanism include which of the following? (Select all that apply.) A. lava flows B. low shield volcanoes C. stratovolcanoes D. ash flow calderas E. lava channels

A, B & E 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.

The most basic subatomic particles include which of the following? (Select all that apply.) A. Protons B. Neutrons C. Isotopes D. Ions E. Electrons

A, B & E See Section 2.2 Origin of the Elements. 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.

Which of the following are true about planetary accretion? (Select all that apply.) A. As these particles accreted, the planets became hot as kinetic energy was converted to thermal energy. B. The planets grew larger and larger via repeated impact. C. The planets became internally differentiated to different degrees. D. The particles that accreted to form the planets were in orbit around the Sun.

A, B, C & D 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.

PHOTO - Which of the craters labeled in this image is a volcanic crater?

B

Which is true about iron meteorites? A. They formed by the condensation of metallic elements from the solar nebula. B. Iron meteorites formed during the internal differentiation of small asteroids. C. They have nothing in common with stony meteorites. D. Iron meteorites are the source of most iron ore on Earth.

B 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.

What is the best explanation for this dome shaped mound on Ceres? A. The mound formed by tectonic deformation. B. Cryovolcanism (ice volcano). C. It is the central peak of an impact crater. D. Erosion of the other rocks away from a resistant mass of igneous rock.

B

According to our best modern day evidence, how long ago was the Big Bang? A. Too far back for us to have any idea. B. About 14 billion years ago. C. About 4.5 billion years ago. D. About 2.5 billion years ago. E. About 65 million years ago at the end of the age of dinosaurs

B As of 2015, best estimate is 13.8 billion yrs ago

When did the planets form? A. The planets formed before the Sun and were then captured by its large gravity. B. The planets formed about the same time as the Sun in a relatively short period of time only a few million years long. C. The planets started to accrete about the same time as the Sun, but then grew slowly over a period of about two billion years. D. The planets are a young feature of the Solar System forming only a few thousands of years ago.

B 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.

Which is true about our current understanding of extrasolar planets (exoplanets)? A. Exoplanets are very rare and only found around very old stars. B. Exoplanets are common and found around many different types of stars. C. Exoplanets are only found around planets with sizes similar to the Sun. D. Exoplanets are so far away, we don't know how many there might be.

B 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.

Craters with central peaks generally ______________. A. are the smallest of all craters B. have terraced walls C. do not occur on the Moon D. form as a result of volcanic activity

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

Which of the following is involved in collisional accretion? A. The selective condensation of elements at different temperatures. B. The aggregation of planetismals when they impact one another. C. The hydrodynamic collapse of nebular gases. D. The gradual change of the gravitational constant.

B 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 following is not a mechanism of heat transport. A. conduction B. magnetism C. convection D. radiation

B 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).

Which is true about the most common volcanic rocks found on the Moon? A. They are of a type not found on Earth. B. Lunar volcanic rocks are similar to the most common volcanic rocks on asteroids and other terrestrial planets. C. Lunar volcanic rocks are high in silica and thus very viscous. D. Most were erupted explosively from stratovolcanoes like Mt. St. Helens.

B Low viscosity basalt is the most common igneous rock on the terrestrial bodies and form lava flow channels, flows, and shield volcanoes.

Why do the planets have different densities? A. Planets get denser with age and some planets are younger than others. B. The planets have different mixtures of ice, silicates, iron, and gas C. The pressure of the interplanetary medium is higher near the Sun so that planets near the Sun have high densities.

B Planets have different amount of elements they are made of. Those made of more dense elements will be more dense.

What is the basis for our understanding of the absolute time scale of the Moon? A. By counting the number of impact craters on a surface we can calculate the age of the surface. B. Rock samples brought back from the Moon have been dated using radiometric techniques to give their absolute ages. C. By carefully mapping the lava flows on the Moon we can calculate its age. D. The ages of the rocks on the surface can be measured using spectrometers on orbiting spacecraft.

B Radiometric ages are determined from radioactive elements in rocks.

How are elements heavier than iron produced? A. As the heaviest elements decay by radioactivity. B. During a supernova explosion C. By gravitational collapse of a star. D. During the formation of a planetary nebula.

B See Section 2.2 Origin of the ElementsOnly elements up to iron are made within stars. All heavier elements are created during the intense event of a supernova.

PHOTO - What process formed these sinuous valleys? Erosion by running water during the wet period of the Moon's history. The eruption of lava flows. Lithospheric faulting. Melting of ground ice.

B 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.

Many supernovas are the result of _____________________. A. the explosive removal of the star's outer layers as hydrogen burning reaches its surface B. collapse of a star with multiple burning shells C. condensation and accretion of the planets D. carbon-burning

B 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.

How did the giant outer planets obtain their thick atmospheres? A. By degassing from their icy interiors. B. By collapse of nebular gas onto a protoplanet's icy core. C. By collection of gas swept into the outer solar system during the T-Tauri stage of the Sun's development. D. As the nebula cooled, the volatile gases condensed onto the planets.

B 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.

Which statement is true for the outer planets of our solar system? A. They produce enough internal energy to glow like the Sun. B. They are largely made of hydrogen and helium. C. They have solid surfaces just below a layer of clouds. D. They lack systems of rings.

B 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 the inner planets depleted (poor) in volatile elements? A. Their constituents condensed at lower temperatures. B. Their constituents condensed at high temperatures. C. They formed from portions of the nebula depleted in these elements. D. They are not depleted in volatiles. E. Hydrogen is not stable inside the orbit of Mars.

B 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.

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)? A. Yes B. No

B These can only show relative dates.

Water ice is __________________________. A. most abundant on the planets of the inner solar system B. most abundant on the moons of the outer planets C. unstable in the outer solar system because of the low pressure that exists there D. rare in the solar system

B 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.

Which of the following statements about the Moon's core are correct? (Select all that apply.) A. The Moon's core is much larger than expected for a planet of its size. B. The Moon's core is probably made of iron. C. The Moon's core was once molten and convected to make a magnetic field. D. As far as we can tell, the Moon is not differentiated, and has no core.

B & C 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.

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." A. between Venus and Earth B. between Mars and Jupiter C. between Uranus and Neptune D. beyond Neptune

B & D 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).

Which of the following are correct about red giant stars? (Select all that apply.) A. Krypton, home to Superman, was a red giant. B. They form as a star expands and the surface cools. C. They are among the stars with the hottest surfaces. D. They evolve from medium-sized stars. They evolve from large stars. Heavy elements like uranium and thorium form in their interiors.

B&D Red giants form by expansion and cooling of the surface of a medium sized star.

Which of the following are the characteristics of the asteroid belt? (Select all that apply.) A. It consists of thousands of small bodies, all less than about 10 km in diameter. B. The asteroids mark the transition from the rocky terrestrial planets to the outer planets. C. Some asteroids appear to be rocky; some seem covered with lava; others seem to be metallic; and yet others may have water ice. D. Many meteorites that fall on Earth come from the asteroid belt.

B, C & D The largest asteroid Ceres is almost 1,000 km across. The asteroids are between Mars and Jupiter and have a wide array of compositions.

Which of the following is correct about the nebulas we see in the sky today? (Select all that apply.) A. They formed during the "Big Bang." B. They are concentrations of interstellar gas and dust. C. Many are the birth grounds of stars. D. Some form when stars explode.

B, C, & D The nebulas we see today are concentrations of gas and dust that give rise to new stars. Some of these nebulas formed by supernovas.

How old are the oldest rocks found so far on the Moon? A. The oldest rocks are 4.8 billion years old and older than any other body in the solar system. B. The oldest rocks are quite young. None exceeded 500 million years old. C. The oldest rocks found on the Moon so far are about 4.5 billion years old. D. The oldest rocks on the Moon are about 2.5 billion years old. The ages of all rocks formed before this have been reset by extensive impact

C

Why are asteroids closer to Jupiter so much darker than those near Mars? A. Solar radiation is stronger on the ones near Mars and has bleached them. B. The asteroids near Mars have a higher content of water ice and are thus lighter in color. C. Dark carbonaceous materials are common on the asteroids near Jupiter. D. The asteroids near Mars are light because they have abundant light color feldspar.

C

Examples of highly refractory materials are ____________________________. A. argon (Ar), ammonia (NH3), and methane (CH4) B. iron (Fe), oxygen (O2), carbon (C), and sulfur (S) C. tungsten (W), osmium (Os), and zirconium (Zr) D. sodium (Na), potassium (K), and rubidium (Rb)—the alkalies

C Refractory elements are those that condense at high temperatures. Volatile elements condense at low temperatures.

The most important mineral in the upper mantle of the Moon is _______. A. iron B. magnesium C. olivine D. peridotite

C - Most common mineral in all of the terrestrial planets mantle.

A giant molecular cloud is best described by which statement? A. It is a hot mass of ionized gas that cannot collapse to form a star. B. It is the ejected shell from a dying red giant star. C. It is a cool mass of gas and dust that can be light years across. D. It is a cloud of gas and dust violently ejected from a supernova explosion.

C 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.

What is the size range of asteroids? A. 0 to 10 km across B. 0 to 100 km across C. 0 to 1000 km across D. 0 to 10,000 km across

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

Which of the following is most accurate about volcanic activity on the asteroids? A. Volcanism never occurred because they are so small. B. On a few asteroids, it is still going on today. C. Volcanism occurred anciently on at least some asteroids. D. Explosive volcanic eruptions propelled fragments to Earth, which we call meteorites.

C Because of small sizes, volcanism would have occurred on asteroids long ago.

How did Earth's atmosphere form? A. By gradual trapping of volatiles from space by its gravitational field. B. By trapping gases from the primeval solar nebula. C. By gaseous exhalations from rocks deep inside. D. By condensation of refractory elements.

C 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.

A "star" that shines, but not as a result of nuclear reactions, is called a __________. A. T-Tauri star B. nebula C. protostar D. supernova E. planetismal

C 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.

The T-Tauri phase of a star's history ______________________. A. strips away the atmosphere of any planet formed around it B. results in the production of planetary condensates C. is typified by extreme fluctuations in energy and a strong magnetic field D. is the result of stellar collapse

C See Section 2.3.3 Nebular Hypothesis for the Formation of the Solar System. Especially figure 2.9. 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

What is the weak layer within a terrestrial planet that behaves like a viscous (flowing) fluid? A. the crust B. the lithosphere C. the asthenosphere D. the mantle

C 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.

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? A. The rates of meteorite bombardment steadily declined after the age of accretion. B. The rate of bombardment increased with time to reach its maximum today. C. Initially, the rate declined smoothly, but there was a later episode of heavy bombardment followed by resumption of the decline. D. Initially, the rate increased smoothly, but there was an episode of much lower impact rates followed by a resumption of the increase.

C 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 of the following types of energy is mostly responsible for crater generation? A. potential energy B. thermal energy C. kinetic energy D. radiogenic energy

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

Consider two planets that are the same age. Which one will have the thicker lithosphere? A. A large rocky planet B. A large gas giant C. A small rocky planet D. A small gas giant

C 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.

What is one evidence suggesting that SNC meteorites came from Mars? A. their red colors B. their low temperatures of formation C. their young ages D. they consist of sedimentary rocks

C 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.

What is the most likely cause of the linear ridges and grooves (see Review PP) near equator of Vesta A. Fracturing caused by extension B. Running water C. Erosion by glacial ice D. Near disruption by a large impact

D

What sets the composition of the moons of the outer planets apart from the inner planets? A. The moons of the outer planets have abundant hydrogen and helium -- like the planets around which they revolve. B. The moons of the outer planets are dominated by nitrogen ice. C. The moons of the outer planets generally have more iron metal and are denser than those of the inner planets. D. The moons of the outer planets generally have lower densities.

D

Which of the following objects is most like Earth in size and composition? A. Mercury B. Ida C. Mars D. Venus

D

Which of the following best describes the orbital evolution of the planets in our solar system according to the Nice Model? A. The orbits of the planets have been more or less the way they are today for over 4.5 billion years. B. The orbits of the inner planets were once much closer to the Sun than they are now and they have slowly moved outward by centripetal forces. C. Earth, Mars, and Venus formed in the outer solar system, but they have slowly spiraled inward to their present orbits near the Sun. D. The orbits of the outer planets changed significantly about 3.9 billion years ago as Uranus and Neptune moved outward from the Sun.

D 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.

The energy of crater formation is expended in all of the following ways except: A. slumping to create terraces B. heat C. seismic (earthquake) waves D. sound E. fracturing of the bedrock

D Impacts can break up rock, cause slumping, and melt rock. But sound does not travel in space and the Moon has no atmosphere, so an impact would not cause sound.

In general , large planets cool _____________________. A. during core formation B. before a lithosphere can form C. more rapidly than small planets of similar composition D. more slowly than small planets of similar compositions

D 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.

What is the age of most meteorites that fall to Earth? A. Less than about 1 billion years old. B. About 1.3 billion years old, the age of the late heavy bombardment. C. Most are less than 1 billion years old, but a few are as old as 4.6 billion years. D. Almost all have ages of about 4.6 billion years.

D Most meteorites are very old (4.6 billion years ago) because most small, really old material never accreted to a major planet.

How will the Sun's life probably end? A. With the development of a black hole. B. By a supernova explosion. C. By passage through a T-Tauri stage. D. With the formation of a planetary nebula.

D 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.

Which of the following is not a way that a planet's atmosphere can lose gas? A. escape to space B. formation of limestone or carbonate materials C. formation of polar ices D. the process of outgassing

D 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 the principal method of light element (up to iron, atomic number 26) production? A. radioactive decay of heavy elements B. gravitational collapse of a star C. isotope reactivation D. nuclear fusion

D See Section 2.2 Origin of the Elements. Elements up to iron are constructed by nuclear fusion within stars.

Which of the following is not a feature formed by impact on the Moon? A. overturned flap on the crater rim B. radiating arms of ejecta around the crater C. terraces on the side of the crater D. sinuous rilles

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

Some stony-iron meteorites appear to have ______________________. A. formed by direct condensation from the solar nebula B. formed during volcanic activity on small asteroids C. fallen to Earth as the most abundant type of meteorite. D. been formed at the core-mantle boundary of an asteroid

D 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.

Which of the following is least important for the appearance of an impact crater developed on the surface of a planet? A. the size of the planet B. the size of the impacting body C. the nature of the surface material (target) D. the presence of a magnetic field E. the presence of an atmosphere

D 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.

Where did the water in Earth's hydrosphere come from? A. From a late bombardment by icy comets. B. From gradual trapping of water molecules in space by Earth's gravitational field. C. From trapping gases from the primeval solar nebula. D. From the volatiles released by volcanoes. E. By condensation of refractory elements.

D 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.

Mare basalts are characteristically _________________________. A. rich in volatile elements like water B. thicker than the lithosphere C. older than the lunar highlands D. very fluid E. similar to other horsey lavas

D similar to motor oil

PHOTO - Which letter marks the youngest lava flow that crosses this part of the lunar maria?

E

What geologic process is most common on asteroids? A. Volcanism B. Erosion by running water C. Erosion by wind D. Tectonic fractures caused by contraction E. Impact cratering

E 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.

Important sources of planetary heat include all of the following except _______________. A. accretion B. core formation C. tidal heating D. decay of radioactive elements E. the Big Bang

E 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.

The surface of the Moon can be divided into two general terrains. What are they? A. bright and dark terrains B. old and young terrains C. high and low terrains D. the maria and the terrae E. all of the above

E 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.

What were the most common solids that condensed from the solar nebular gases? A. They were silicates that lacked water. B. They were silicates that contained water. C. They consisted of carbonaceous material. D. They were made of iron. E. They were water ice.

E 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.

The inner planets ______________________. A. Have the same composition as the outer planets B. Same size as the outer planets C. Have an orbiting system of rings D. Have several moons E. All incorrect.

E.

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. LOOK AT PHONE AND ORDER THE PHOTOS

Gas and 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.

LABEL THE AVERAGE TEMP OVER AGE SPIKE DIAGRAM.

Large planets will have the highest initial internal temperature and will cool more slowly. So the larger the planet the higher the internal temperature at any given time.

PHOTO - Graph showing impact crater size versus number of craters.

Mare Imbrium has the lowest cater freq = the youngest.

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

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto

PHOTO - Arrange these impact craters from smallest to larges.

With increasing size a craters morphology changes from bowl shaped, to terraced, to a central peak, to a peak ring/s.