AST EXAM 2

Where do Uranus's and Neptune's high magnetic fields originate? a. molten rocky cores b. salty oceans c. large magnetospheres d. metallic hydrogen layers

B

An observer outside our Solar System, who monitors the velocity of our Sun over time, will find that its velocity varies by ±12 m/s over a period of 12 years because of: a. Jupiter's gravitational pull. b. Earth's gravitational pull. c. convection on the Sun's surface. d. the sunspot cycle.

A

Earth releases the energy it receives from the Sun by emitting ________ radiation. a. infrared b. visible c. ultraviolet d. radio

A

Given the thickness and composition of Venus's atmosphere, by how much would you expect its average surface temperature to change between day and night? a. almost no change at all b. by tens of kelvins (like Earth) c. by hundreds of kelvins (like Mercury) d. The answer depends on where Venus is in its orbit (closer to or farther from the Sun).

A

How might liquid water exist on Mars where the temperature is routinely below the freezing point of water? a. Martian water may contain salts, which lowers the freezing temperature of the water. b. Ice is melted by the heat of geological activity. c. Liquid water emerges from martian volcanoes. d. Water precipitates from the martian atmosphere.

A

Rings of giant planets are very thin compared to their diameters mainly because: a. of collisions between ring particles. b. moons that tidally disrupt have small diameters. c. energy is conserved when a moon tidally disrupts. d. the planets have large tidal forces.

A

The Moon probably formed: a. out of a collision between Earth and a Mars-sized object. b. when the Earth's gravity captured a planetesimal. c. when the accretion disk around Earth fragmented. d. when planetesimals collided to form a more massive object

A

Two planets, one the size of the Earth and the second with one-fourth the diameter of the Earth, each form at a distance of 1 AU from a star like our sun. Which of the following statements is true? a. The smaller planet would have little or no atmosphere. b. The larger planet would be less volcanically active. c. The larger planet would cool faster. d. The smaller planet would have a stronger magnetic field.

A

What happens to the gravitational energy of gas as it falls toward and eventually hits the accretion disk surrounding a protostar? a. It is converted into thermal energy, heating the disk. b. It is converted into light energy, giving off a flash of light upon impact. c. It is converted into potential energy as the gas plows through the disk and comes out the other side. d. It simply dissipates.

A

What is the main driver that causes Hadley circulation in a planet's atmosphere to break up into zonal winds? a. the planet's rapid rotation b. heating from the solar wind c. hurricanes developing along the planet's equator d. convection driven by solar heating

A

When astronomers began searching for extrasolar planets, they were surprised to discover Jupiter-sized planets much closer than 1 AU to their parent stars. Why is this surprising? a. These planets must have formed at a larger radius where temperatures were cooler and then migrated inward. b. Jupiter-sized, rocky planets were thought to be uncommon in other solar systems. c. These planets must be the remnants of failed stars. d. Earth-like planets must be rarer than Jupiter-sized planets in other solar systems.

A

When we see a region of a planet that is NOT as heavily cratered as other regions, we conclude that a. the surface in the region is younger than the surface in more heavily cratered regions. b. there is little volcanic activity to create craters. c. the planet formed after the age of bombardment and was not hit by as many leftover planetesimals. d. the surface in the region is older than the surface in more heavily cratered regions. e. the planet is rotating very slowly and only one side was hit by impactors.

A

Which planetary surface process probably created most of the features on the surface we see in the image above? a. techtonics b. cratering c. volcanism d. none of the above

A

Why can water exist in the hot interiors of the giant planets? a. The pressure is high enough to prevent the water from becoming vapor. b. Some of the metallic hydrogen in the core mixes with oxygen. c. Regions of the interior are cooler than the surrounding regions. d. Water released from moons via cryovolcanism is absorbed.

A

Why didn't a planet form where the asteroid belt is now located? a. Gravitational tugs from Jupiter prevented material from collecting to form a planet. b. The temperature in that portion of the solar nebula was just right to prevent rock from sticking together. c. There was too much rocky material to form a terrestrial planet, but not enough gaseous material to form a jovian planet. d. There was not enough material in this part of the solar nebula to form a planet.

A

In the past, the Moon was closer to Earth, and the differences in the heights of the ocean at high and low tides were: a. the same. b. larger. c. smaller. d. tides were nonexistent in the past

B

Place the features in order from oldest to youngest. a. A, B, C, D b. E, D, C, B c. D, C, E, A d. D, C, A, B e. E, A, B, C

B

The increasing temperature of the core of a collapsing cloud of gas is due to: a. radiation. b. collisions between gas molecules. c. increased spin rate of the cloud. d. fragmentation of the core.

B

Which of the following factors does NOT directly influence the temperature of a planet? a. the luminosity of the Sun b. the distance of the planet from the Sun c. the albedo of the planet d. the size of the planet

D

An asteroid with an albedo of 0.1 and a comet with an albedo of 0.6 are orbiting at roughly the same distance from the Sun. How do their temperatures compare? a. They both have the same temperature. b. The comet is hotter than the asteroid. c. The asteroid is hotter than the comet. d. You must know their distance to compare their temperatures.

C

. The main greenhouse gases in the atmosphere of the terrestrial planets are: a. oxygen and nitrogen. b. methane and ozone. c. carbon dioxide and water vapor. d. hydrogen and helium.

C

An observer measures the spectrum of two planets emitting as blackbodies, one with a temperature of T1=300K, similar to the Earth's, and the second with a temperature of T2=800K, similar to Venus'. From this, you determine the relationship between their peak wavlengths and luminosities to be: a. λ1>λ2, Planet 1 is brighter b. λ1<λ2, Planet 1 is brighter c. λ1>λ2, Planet 2 is brighter d. λ1<λ2, Planet 2 is brighter

C

Comet nuclei, absent their tails, are typically very dark because: a. they are made of water ice. b. they have iron and nickel mixed with ice. c. they have organic molecules mixed with ice. d. they are covered in rock.

C

Conservation of angular momentum slows a cloud's collapse: a. equally in all directions. b. only when the cloud is not rotating initially. c. mostly along directions perpendicular to the cloud's axis of rotation. d. mostly at the poles that lie along the cloud's axis of rotation.

C

Continents on the Earth "drift" due to effects of a. tides from the Moon b. tides from the Moon and the Sun c. currents of hot material in Earth's mantle d. the rotation of Earth's liquid outer core e. the Earth's tilt and rotation on it's axis

C

HD 177830 b was discovered using the radial velocity method. The plot below shows how the star's measured radial velocity changes with time. Approximately how long is the planet's orbital period (in years)? a. 0.5 years b. 0.8 years c. 1.1 years d. 2.3 year

C

How can moons be more geologically active than planets? a. Some moons have magnetic fields that are stronger than planets. b. Some moons have a faster rotation rate than some planets. c. The tidal stresses experienced by some moons can heat the interior. d. Moons that are denser than the planets they orbit attract more colliding objects.

C

Meteorites contain clues to all of the following EXCEPT: a. the age of the Solar System. b. the temperature in the early solar nebula. c. changes in the rate of cratering in the early Solar System. d. the composition of the primitive Solar System.

C

Neptune and Uranus probably took longer to form than Jupiter and Saturn because the solar nebula was ________ at the radius of Neptune and Uranus. a. rotating faster b. composed of rockier planetesimals c. not as dense d. hotter

C

The Doppler shift can be used to determine the ________ of an object. a. energy c. radial velocity b. temperature d. no radiation

C

The current theory is that a planet will have a strong magnetic field if it has: a. fast rotation and a solid core. b. slow rotation and a liquid core. c. fast rotation and a liquid core. d. slow rotation and a solid core.

C

What is the goal of comparative planetology? a. To memorize as much as one can about the features and characteristics of each individual planet or moon. b. To bring back to Earth samples of rocks from many planets and moons in order to do radioactive dating. c. To find common features among planets and moons to understand how they formed and changed. d. To figure out which planets and moons were not affected by gravitational forces and other processes.

C

Which of the following comets would you observe to study the best example of pristine solar system material. a. A comet with a 10 year orbit. b. A comet with a 100 year orbit. c. A comet with a 1,000 year orbit. d. All represent the same pristine material.

C

Which property of a moon might lead you to hypothesize it was a captured asteroid? a. It is tidally locked. b. Its orbital axis is tilted by 10° compared to the planet's rotational axis. c. It rotates clockwise around the planet when viewed from the planet's north pole. d. Its surface is very smooth and lacks craters.

C

. Earth's innermost core is solid, not liquid, because: a. the core temperature is too low to melt iron. b. differentiation caused all of the heavy, solid material to sink to the bottom while Earth was forming. c. all the liquid has moved up into the mantle via convection. d. the pressure is too high for a liquid state.

D

How do Saturn's shepherd moons help maintain the stability of Saturn's rings? a. Their magnetic fields confine the rings' orbits. b. Their gravity periodically captures solar system debris and adds it to the ring system. c. They periodically collide with larger ring objects, pulverizing them. d. Their gravitational interactions with ring material maintains the orbital stability of the rings.

D

If it were not for the greenhouse effect on Earth, a. there would be no liquid water. b. life as we know it would not have developed. c. it would be much colder. d. all of the above

D

In what way is Venus most similar to Earth? a. both planets have similar surface geology. b. both planets have very similar atmospheres today. c. both planets have warm days and cool nights. d. both planets are nearly the same size.

D

Mars, Venus, and Earth are much less heavily cratered than Mercury and the Moon. This is explained by the fact that: a. the rate of cratering in the early Solar System was strongly dependent on location. b. all three have thick, protective atmospheres. c. Earth and Venus were shielded from impacts by the Moon, and Mars was protected by the asteroid belt. d. Mars, Venus, and Earth were geologically active longer than Mercury and the Moon.

D

The Aurora Borealis, or Northern Lights, are caused by: a. decay of radiative materials in the atmosphere. b. absorption and remission of solar UV light. c. static electricity in the atmosphere. d. energetic particles from the Sun interacting with Earth's atmosphere.

D

The one orbital characteristic both short- and long-period comets share is: a. mostly prograde orbits. b. orbits with completely random tilts. c. orbital periods longer than that of any planet. d. highly eccentric orbits.

D

The relative ages of the surface of the Moon or any other planetary body can be determined based on a. the number of craters. b. the size of craters. c. the density of craters. d. the number and density of craters. e. age-dating of actual samples only

D

The source or sources of the internal heat of Earth are: a. tidal stress. b. radioactive decay. c. leftover heat of planetary formation. d. all of the above

D

Volatile and refractory materials differ in their: a. melting temperatures. b. density at a given temperature. c. composition. d. all of the above

D

Volcanism is more likely on a planet that a. is closer to the Sun. b. is struck more often by meteors and solar system debris. c. doesn't have an atmosphere or oceans. d. has high internal temperatures.

D

We refer to some of the inner regions of Jupiter and Saturn as metallic hydrogen because they: a. are as dense as lead. b. are solid. c. provide support for the upper layers of hydrogen and helium. d. efficiently conduct electricity.

D

Whether or not a planet is composed mostly of rock or gas is set by: a. its mass. b. its temperature. c. the distance from the star that it orbits. d. all of the above

D

Which of the following can be used as an indicator of the age of a moon's surface? a. surface brightness b. crater density c. volcanic activity d. all of the above

D

Which of the following is NOT an exception to the general patterns in the solar system? a. The extreme axial tilt of Uranus. b. The counterclockwise rotation of Venus. c. The retrograde orbit of Triton around Neptune. d. The large size of the Earth's moon. e. The rings of Saturn.

E