Question 1

The theory that describes the formation of planetary systems is the:
A) condensation theory.
B) core accretion model.
C) disk theory.
D) protoplanetary theory.

Accepted Answer

The answer of The theory that describes the formation of...

Question 2

The physical principle most directly responsible for the shape of planetary systems is:
A) Newton's second law of motion.
B) the universal law of gravity.
C) conservation of angular momentum.
D) conservation of energy.

Accepted Answer

The conservation of angular momentum is the physical principle that is most directly responsible for the shape of planetary systems. As a rotating cloud of gas and dust begins to collapse, conservation of angular momentum causes it to spin faster and flatten into a disk shape. This disk then gives rise to planets and other objects in the solar system, which all share the same overall direction of rotation due to the conservation of angular momentum.

Question 3

The orbits of the planets in our Solar System:
A) imply that the planets formed elsewhere and were captured by the Sun's gravity.
B) all proceed in the same direction.
C) have a wide range of inclinations.
D) have semimajor axes that follow a regular, repeating pattern.

Accepted Answer

The planets in our Solar System all orbit the Sun in the same direction, which is counterclockwise when viewed from above the Sun's north pole. This uniform direction of orbit is a result of the planets forming from a rotating disk of gas and dust that surrounded the young Sun.

Question 4

Suppose Jupiter's gravity disturbs an asteroid and sends it on an elliptical orbit with a high eccentricity.If the semimajor axis of the resulting orbit is 2 AU,the object would be classified as a(n):
A) Kuiper Belt object.
B) C-type asteroid.
C) Trojan asteroid.
D) Earth-crossing asteroid.

Accepted Answer

An elliptical orbit with a high eccentricity and a semimajor axis of 2 AU implies that the asteroid crosses the Earth's orbit, which makes it an Earth-crossing asteroid. Kuiper Belt objects are icy bodies beyond the orbit of Neptune, C-type asteroids are carbonaceous asteroids found in the asteroid belt, and Trojan asteroids are found in stable Lagrange points of a planet's orbit.

Question 5

How do comets from the Oort Cloud differ from comets from the Kuiper Belt?
A) Oort Cloud comets have shorter periods.
B) Oort Cloud comets have smaller masses.
C) Oort Cloud comets have different compositions.
D) Oort Cloud comets have larger inclinations, on average.

Accepted Answer

Oort Cloud comets are believed to have larger inclinations on average, meaning their orbits can be more steeply tilted relative to the plane of the solar system, compared to comets from the Kuiper Belt. This is because the Oort Cloud is a spherical shell surrounding the solar system, allowing comets from this region to come from any direction, whereas the Kuiper Belt is more disk-shaped and lies roughly in the same plane as the planets.

Question 6

Compared to our Solar System,the majority of exoplanets have orbits with:
A) higher eccentricity.
B) higher inclinations.
C) smaller semimajor axes.
D) all of the above.

Accepted Answer

The answer of Compared to our Solar System,the majority of...

Question 7

Hot Jupiters provide evidence for:
A) the greenhouse effect.
B) super-Earths.
C) the condensation theory.
D) planetary migration.

Accepted Answer

Hot Jupiters, gas giant planets that orbit very close to their stars, were initially thought to be impossible according to the condensation theory which explains how planets form. The discovery of hot Jupiters was a strong indication that these planets migrated inward towards their stars, providing evidence for planetary migration.

Question 8

Venus is unusual within the Solar System because it:
A) rotates in the opposite sense from its orbit around the Sun.
B) is so massive.
C) has no evidence for active plate tectonics.
D) has a highly inclined orbit.

Accepted Answer

Venus is the only planet in the Solar System that rotates in the opposite direction to its orbit around the Sun. This means that its day (the time it takes to complete one rotation on its axis) is longer than its year (the time it takes to complete one orbit around the Sun).

Question 9

The most successful method to date in detecting Earth-sized exoplanets is:
A) the radial velocity method.
B) the transit method.
C) direct imaging.
D) gravitational lensing.

Accepted Answer

The transit method involves detecting the slight dimming of a star's brightness as a planet passes in front of it. This method has been very successful in detecting Earth-sized exoplanets, as it is sensitive to small planets and can reveal information about their size and orbital period. Other methods, such as radial velocity and direct imaging, have been effective in detecting larger exoplanets but are less sensitive to Earth-sized planets. Gravitational lensing can also detect Earth-sized planets, but it is a rare occurrence and difficult to observe. Therefore, the transit method is currently the most successful method for detecting Earth-sized exoplanets.

Question 10

A planet orbiting a star with a mass one-quarter that of the Sun has an orbital radius of 1/25 AU.If Earth's orbital velocity is 30 km/s,what is the orbital velocity of this planet?
A) 15 km/s
B) 30 km/s
C) 60 km/s
D) 75 km/s

Accepted Answer

The orbital velocity (v) of a planet is given by v = sqrt(GM/r), where G is the gravitational constant, M is the mass of the star, and r is the orbital radius. Since the star's mass is one-quarter of the Sun's, and the orbital radius is 1/25 AU, the velocity is v = sqrt((1/4) * GM_sun / (1/25) AU) = sqrt(25/4) * v_earth = (5/2) * 30 km/s = 75 km/s.

Question 11

Arrange the following solar system bodies in order of increasing average orbital inclination:
A) long-period comets, short-period comets, planets, and the asteroid belt.
B) planets, the asteroid belt, short-period comets, and long-period comets.
C) the asteroid belt, planets, long-period comets, and short-period comets.
D) long-period comets, short-period comets, the asteroid belt, and planets.

Accepted Answer

Planets generally have low orbital inclinations, reflecting their formation from a flattened disk of material around the Sun. The asteroid belt also has a relatively low average inclination, but it is slightly more inclined than the planets. Short-period comets, which originate from the Kuiper Belt, have higher inclinations on average. Long-period comets, coming from the Oort Cloud, have the highest inclinations, often with orbits significantly inclined to the ecliptic plane.

Question 12

The figure below shows two stars.Star A has a mass twice that of our Sun,while Star B has a mass four times that of our Sun.Which labeled point identifies the center of mass of the system? 
A) A
B) B
C) C
D) D

Accepted Answer

The center of mass of a binary star system is the point around which the two stars orbit. Since Star A has twice the mass of our Sun and Star B has four times the mass of our Sun, Star B exerts twice the gravitational force on Star A as Star A exerts on Star B. This means that the center of mass must be closer to Star B than to Star A. Therefore, the correct choice is point C, which is closer to Star B.

Question 13

The ion tail of a comet points:
A) in the direction of the solar wind.
B) in a trailing orbit near the comet.
C) in the direction of gas jets flowing out of the comet's nucleus.
D) directly behind the comet's position along its orbit.

Accepted Answer

The ion tail of a comet always points directly away from the Sun because it is shaped by the solar wind, which consists of charged particles emitted by the Sun. These particles push the ionized gases of the comet's tail directly away from the Sun, regardless of the comet's direction of travel.

Question 14

The radial velocity method is best at detecting exoplanets with ________ orbital radii and ________ masses.
A) small; small
B) small; large
C) large; large
D) large; small

Accepted Answer

The radial velocity method is most effective at detecting exoplanets that are close to their stars (small orbital radii) and have large masses because these characteristics cause the most significant gravitational effects on the star, making it easier to detect the star's wobble.

Question 15

Astronomers detect a gas giant exoplanet orbiting its host star on an eccentric orbit with a semimajor axis of 100 AU.This provides evidence for:
A) hot Jupiters.
B) eccentric disks.
C) scattering.
D) the snow line.

Accepted Answer

Scattering is a process that can lead to planets having highly eccentric orbits, as interactions with other planets or stellar objects can significantly alter their trajectories. The detection of a gas giant with an eccentric orbit at a distance of 100 AU from its host star suggests that scattering events have likely played a role in shaping its orbit.

Question 16

The majority of meteoroids are most similar to:
A) the Moon.
B) comets.
C) S-type asteroids.
D) C-type asteroids.

Accepted Answer

The answer of The majority of meteoroids are most similar...

Question 17

C-type asteroids differ from S-type asteroids in that C-type asteroids:
A) never underwent differentiation.
B) never have Earth-crossing orbits.
C) are more reflective.
D) are more numerous.

Accepted Answer

C-type asteroids are dark and carbonaceous, indicating that they contain organic compounds and have not undergone significant heating or differentiation. This contrasts with S-type asteroids, which are silicaceous and rocky, indicating that they have undergone differentiation and are composed of materials that have been processed at high temperatures. Additionally, the other three answer choices are not necessarily true of all C-type asteroids, making answer choice A the best option.

Question 18

The most successful method to date in determining an exoplanet's radius is:
A) the transit method.
B) the radial velocity method.
C) direct imaging.
D) gravitational lensing.

Accepted Answer

The transit method involves measuring the slight dimming of a star's light as an exoplanet passes in front of it. This allows astronomers to determine the size of the exoplanet relative to its host star. This method has been the most successful so far in determining exoplanet radii, as it has detected thousands of exoplanets and has provided a wealth of data for statistical analysis. The other methods listed have also been used to determine exoplanet radii, but they are less widely used and/or less successful overall.

Question 19

A planet with a mass of 7-ME is a(n):
A) terrestrial planet.
B) super-Earth.
C) ice giant.
D) gas giant.

Accepted Answer

A planet with a mass of 7-ME is classified as a super-Earth, which is larger than Earth but smaller than a gas giant.

Question 20

The coma of a comet glows because:
A) of heating produced by radioactive decay in the interior of the comet.
B) atoms become neutral within the coma.
C) of heating and sublimation of the comet's nucleus by sunlight.
D) of refraction by dust grains.

Accepted Answer

The coma of a comet glows due to the heating and sublimation of the comet's nucleus by sunlight. As the ice and dust on the nucleus heats up, it turns into gas, creating a cloud of gas and dust around the nucleus which reflects sunlight, creating the glow of the coma.

Quiz 5: The Architecture and Birth of Planetary Systems

The theory that describes the formation of planetary systems is the:

The physical principle most directly responsible for the shape of planetary systems is:

The orbits of the planets in our Solar System:

Suppose Jupiter's gravity disturbs an asteroid and sends it on an elliptical orbit with a high eccentricity.If the semimajor axis of the resulting orbit is 2 AU,the object would be classified as a(n) :

How do comets from the Oort Cloud differ from comets from the Kuiper Belt?

Compared to our Solar System,the majority of exoplanets have orbits with:

Hot Jupiters provide evidence for:

Venus is unusual within the Solar System because it:

The most successful method to date in detecting Earth-sized exoplanets is:

A planet orbiting a star with a mass one-quarter that of the Sun has an orbital radius of 1/25 AU.If Earth's orbital velocity is 30 km/s,what is the orbital velocity of this planet?

Arrange the following solar system bodies in order of increasing average orbital inclination:

The figure below shows two stars.Star A has a mass twice that of our Sun,while Star B has a mass four times that of our Sun.Which labeled point identifies the center of mass of the system?

The ion tail of a comet points:

The radial velocity method is best at detecting exoplanets with orbital radii and masses.

Astronomers detect a gas giant exoplanet orbiting its host star on an eccentric orbit with a semimajor axis of 100 AU.This provides evidence for:

The majority of meteoroids are most similar to:

C-type asteroids differ from S-type asteroids in that C-type asteroids:

The most successful method to date in determining an exoplanet's radius is:

A planet with a mass of 7-ME is a(n) :

The coma of a comet glows because: