Question 1

Which galactic phenomenon is triggered by the same process as spiral structure?
A) galactic bars
B) globular clusters
C) tidal streams
D) the formation of spirals from ellipticals

Accepted Answer

Galactic bars are triggered by the same gravitational forces that trigger spiral structures. The same disturbances that cause spiral arms to form can also cause the central region of a galaxy to become elongated and form a bar.

Question 2

Edwin Hubble believed that:
A) galaxies evolve from ellipticals to spirals.
B) spiral nebulae are part of the Milky Way.
C) elliptical galaxies are always more distant than spiral galaxies.
D) lenticular galaxies are the endpoint of galactic evolution.

Accepted Answer

Hubble proposed the "tuning fork" diagram, which suggests a morphological classification of galaxies. He did not believe in a linear evolution from ellipticals to spirals, but his work laid the groundwork for understanding galaxy morphology. The correct interpretation of his work is that he identified different types of galaxies (e.g., ellipticals, spirals) but did not assert a specific evolutionary path from one type to another as stated in the options. However, the closest to his contributions is the idea of galaxies evolving, which is somewhat reflected in option A, albeit not perfectly accurate in the context of modern understanding.

Question 3

In the early 20th century,some astronomers incorrectly believed that they could observe features in spiral nebulae rotate over the course of a few years.If those observations were correct,what would they have immediately suggested about the nature of these nebulae?
A) that they were island universes
B) that they were inside the Milky Way
C) that they were forming stars
D) that they were accretion disks

Accepted Answer

If features in spiral nebulae appeared to be rotating, it would suggest that they were co-rotating with the Milky Way and therefore located within our galaxy rather than being "island universes" (answer A). The other options (C and D) are not necessarily related to observing rotational features in nebulae.

Question 4

Edwin Hubble classified elliptical galaxies according to their:
A) size.
B) color.
C) apparent shape.
D) velocities.

Accepted Answer

Edwin Hubble classified elliptical galaxies according to their apparent shape, which ranges from nearly spherical to highly elongated.

Question 5

What was the subject of the "Great Debate" in astronomy?
A) the truth of the geocentric and heliocentric theories
B) the age of the Universe
C) the nature of spiral nebulae
D) the truth of the Big Bang model

Accepted Answer

The "Great Debate" in astronomy was a scientific debate that took place in 1920 between two prominent astronomers, Harlow Shapley and Heber Curtis, about the nature of spiral nebulae. Shapley believed that these nebulae were part of our Milky Way galaxy, while Curtis argued that they were actually separate galaxies outside of the Milky Way. The debate ultimately helped to confirm Curtis's view and solidified the idea of an expanding universe. The other options (A, B, D) were also important topics in astronomy, but were not the focus of the "Great Debate."

Question 6

Which astronomer definitively established the existence of galaxies outside the Milky Way?
A) Galileo
B) William Herschel
C) Harlow Shapley
D) Edwin Hubble

Accepted Answer

Edwin Hubble definitively established the existence of galaxies outside the Milky Way through his observations and measurements of the Andromeda galaxy and other distant nebulae in the early 20th century.

Question 7

Because of an obscuring atmosphere,an observer in a distant galaxy can only see the nearest 1,000 stars to his or her home planet.How could the observer most directly determine that he or she lives inside an elliptical galaxy?
A) by measuring the brightnesses of the stars
B) by mapping the locations of the stars on the sky
C) by measuring the differences in velocities between the stars
D) by measuring the masses of the stars

Accepted Answer

Measuring the differences in velocities between the stars could allow the observer to determine whether they live in an elliptical galaxy. In elliptical galaxies, stars tend to have more random orbits and velocities compared to spiral galaxies, where stars often have more ordered circular orbits. By measuring the differences in velocities between the stars, the observer could look for any patterns or trends that suggest the galaxy has an elliptical shape.

Question 8

A galaxy with a total mass of 10⁶ M_Sun is most likely to be: A) a spiral. B) a barred spiral. C) a dwarf elliptical. D) a lenticular.

Accepted Answer

A galaxy with a total mass of 10^6 solar masses is most likely to be a dwarf elliptical galaxy, as this mass is relatively small for galaxies, and dwarf ellipticals are among the smallest and least massive galaxy types.

Question 9

The figure below shows a schematic of the Hubble tuning-fork diagram.At which labeled point will a lenticular galaxy be placed? 
A) A
B) B
C) C
D) D

Accepted Answer

The answer of The figure below shows a schematic of...

Question 10

How do stars move inside of ellipticals?
A) They move along random orbits.
B) They all circulate in the same direction with little variation.
C) They all circulate in the same direction, but with some variation in velocities.
D) They move on mostly vertical orbits.

Accepted Answer

Stars in elliptical galaxies move along random orbits, unlike the more orderly rotation seen in spiral galaxies. This randomness contributes to the elliptical shape of these galaxies.

Question 11

A galaxy appears cigar-shaped on the sky.It has a population of globular clusters and predominantly old stars.It is most likely a(n):
A) spiral.
B) barred spiral.
C) elliptical.
D) irregular.

Accepted Answer

A galaxy with a cigar-shaped appearance and a population of globular clusters and predominantly old stars is most likely an elliptical galaxy. Spiral galaxies have a flattened disk shape, barred spiral galaxies have a central bar structure, and irregular galaxies do not have a distinct shape.

Question 12

A low-mass galaxy is situated 10 kiloparsecs from a flocculent spiral galaxy.Which of the following is most likely to describe the low-mass galaxy?
A) irregular
B) spiral
C) barred spiral
D) elliptical

Accepted Answer

Low-mass galaxies are typically irregular in shape and lack the spiral arms and structure of more massive galaxies. Additionally, being situated 10 kiloparsecs away from a flocculent spiral galaxy would not have a significant influence on the shape of the low-mass galaxy, so we can conclude that it is most likely an irregular galaxy.

Question 13

An observer detects a galaxy with a blue color,lots of 21-cm emission,and a moderate total mass.It is most likely a(n):
A) irregular.
B) elliptical.
C) lenticular.
D) spiral.

Accepted Answer

A galaxy with blue color and lots of 21-cm emission indicates ongoing star formation, which is commonly found in spiral galaxies. An irregular galaxy would also have ongoing star formation, but 21-cm emission is usually stronger in spiral galaxies. An elliptical galaxy typically has little or no ongoing star formation, and a lenticular galaxy is a transition between spiral and elliptical galaxies, but still has less ongoing star formation. The moderate total mass does not provide strong clues for classification since all four types of galaxies can have moderate masses.

Question 14

What is "spectroscopic parallax"?
A) using stellar spectra to measure distances
B) using the apparent angular motion of stars to measure distances
C) using the redshifts of galaxy absorption lines to measure distances
D) using the apparent angular motion of galaxies to measure distances

Accepted Answer

Spectroscopic parallax is the use of stellar spectra to measure the distance to a star. By analyzing the spectra of a star, astronomers can determine its temperature, luminosity, and chemical composition. These properties can then be used to estimate the star's distance from Earth, just as in traditional parallax measurements.

Question 15

In a barred spiral galaxy,the spiral:
A) structure is always very obvious.
B) arms extend from the ends of the bar.
C) structure gradually destroys the bar.
D) arms are more tightly wound than in spiral galaxies without bars.

Accepted Answer

In a barred spiral galaxy, the arms extend from the ends of the bar, creating a distinct pattern of two spiral arms that appear to be connected to a central bar-shaped structure. This is a defining characteristic of barred spiral galaxies. The other options are not universally true for all barred spiral galaxies.

Question 16

In the context of the cosmic distance ladder,to what does calibration refer?
A) measuring Hubble's constant
B) tuning one distance determination method to another
C) measuring the distance to Cepheid variable stars
D) defining units

Accepted Answer

Calibration refers to the process of tuning one distance determination method to another by comparing the distances obtained using different methods for the same objects. This is necessary for establishing the accuracy and reliability of distance measurements using different techniques, and for building a consistent and self-consistent cosmic distance ladder.

Question 17

The figure below shows a schematic of the Hubble tuning-fork diagram.At which labeled point might a spiral galaxy with a very small bulge lie? 
A) A
B) B
C) C
D) D

Accepted Answer

Point B represents spiral galaxies with small bulges, also known as Sb galaxies. This is because they have a small central bulge and tightly wound spiral arms. Therefore, a spiral galaxy with a very small bulge would most likely fall within this category and be represented by point B on the diagram.

Question 18

An elliptical galaxy has:
A) blue stars and plunging orbits.
B) red stars and lots of gas and dust.
C) red stars and plunging orbits.
D) blue stars and lots of gas and dust.

Accepted Answer

Elliptical galaxies are mostly composed of old, red stars, and their orbits are typically very circular or elliptical rather than plunging. Option A and D are incorrect because elliptical galaxies do not typically have blue stars or much gas and dust. Option B is also incorrect because red stars indicate older populations, and elliptical galaxies do not typically have large amounts of gas and dust.

Question 19

A spiral galaxy is observed to have undergone a recent episode of intense star formation near its center.Which of the following is this galaxy most likely to have had in its recent past?
A) a flocculent phase
B) a grand design phase
C) globular clusters
D) a bar

Accepted Answer

A bar in a spiral galaxy can funnel gas and dust towards the center, promoting star formation. The recent episode of intense star formation near the center of the galaxy suggests that there may have been a bar phase in the galaxy's recent past.

Question 20

As a result of collisions,galaxies are most likely to evolve from:
A) ellipticals to spirals.
B) spirals to ellipticals.
C) ellipticals to irregulars.
D) irregulars to ellipticals.

Accepted Answer

The most common outcome of galactic collisions is the merging of two or more galaxies. When two spiral galaxies merge, the result is usually an elliptical galaxy. Therefore, spirals are more likely to evolve into ellipticals rather than the reverse.

Quiz 16: A Universe of Galaxies

Which galactic phenomenon is triggered by the same process as spiral structure?

Edwin Hubble believed that:

In the early 20th century,some astronomers incorrectly believed that they could observe features in spiral nebulae rotate over the course of a few years.If those observations were correct,what would they have immediately suggested about the nature of these nebulae?

Edwin Hubble classified elliptical galaxies according to their:

What was the subject of the "Great Debate" in astronomy?

Which astronomer definitively established the existence of galaxies outside the Milky Way?

Because of an obscuring atmosphere,an observer in a distant galaxy can only see the nearest 1,000 stars to his or her home planet.How could the observer most directly determine that he or she lives inside an elliptical galaxy?

A galaxy with a total mass of 10⁶ M_Sun is most likely to be:

The figure below shows a schematic of the Hubble tuning-fork diagram.At which labeled point will a lenticular galaxy be placed?

How do stars move inside of ellipticals?

A galaxy appears cigar-shaped on the sky.It has a population of globular clusters and predominantly old stars.It is most likely a(n) :

A low-mass galaxy is situated 10 kiloparsecs from a flocculent spiral galaxy.Which of the following is most likely to describe the low-mass galaxy?

An observer detects a galaxy with a blue color,lots of 21-cm emission,and a moderate total mass.It is most likely a(n) :

What is "spectroscopic parallax"?

In a barred spiral galaxy,the spiral:

In the context of the cosmic distance ladder,to what does calibration refer?

The figure below shows a schematic of the Hubble tuning-fork diagram.At which labeled point might a spiral galaxy with a very small bulge lie?

An elliptical galaxy has:

A spiral galaxy is observed to have undergone a recent episode of intense star formation near its center.Which of the following is this galaxy most likely to have had in its recent past?

As a result of collisions,galaxies are most likely to evolve from: