Question 1

The higher the luminosity (intrinsic brightness) a Cepheid variable is,

Accepted Answer

A)  the smaller its mass 
B)  the lower it is on the main sequence of the H-R diagram 
C)  the longer the period of its variations 
D)  the closer it is to us 
E)  the larger the telescope we need to observe it 
A)  the smaller its mass 
B)  the lower it is on the main sequence of the H-R diagram 
C)  the longer the period of its variations 
D)  the closer it is to us 
E)  the larger the telescope we need to observe it C

Question 2

Which of the following stars is a Cepheid variable?

Accepted Answer

A)  Sirius 
B)  Betelgeuse 
C)  Rigel 
D)  Mizar 
E)  Polaris 
A)  Sirius 
B)  Betelgeuse 
C)  Rigel 
D)  Mizar 
E)  Polaris E

Question 3

If a star is 20 parsecs away, its parallax must be:

Accepted Answer

A)  20 arcseconds 
B)  2 arcseconds 
C)  ½ arcsecond 
D)  1/20th of an arcsecond 
E)  this can't be figured out from the information given 
A)  20 arcseconds 
B)  2 arcseconds 
C)  ½ arcsecond 
D)  1/20th of an arcsecond 
E)  this can't be figured out from the information given D

Question 4

As astronomers use the term, the parallax of a star is

Accepted Answer

A)  one half of the Doppler shift due to its radial velocity 
B)  always equal to 1 AU 
C)  one half the angle that a star shifts when seen from opposite sides of the Earth's orbit 
D)  the time it takes a Cepheid variable star to go through one cycle of its brightness changes 
E)  the time it takes for a star to move one second of arc of proper motion 
A)  one half of the Doppler shift due to its radial velocity 
B)  always equal to 1 AU 
C)  one half the angle that a star shifts when seen from opposite sides of the Earth's orbit 
D)  the time it takes a Cepheid variable star to go through one cycle of its brightness changes 
E)  the time it takes for a star to move one second of arc of proper motion

Question 5

How did Henrietta Leavitt "calibrate" her period-luminosity relationship for Cepheid variable stars? In other words, how did she make the general idea into a numerical rule?

Accepted Answer

A)  by finding cepheids in star clusters whose distance was known in another way 
B)  because the star closest to us is a Cepheid variable and we know its distance 
C)  by noting that the period was related to the luminosity in all stars 
D)  by measuring the Doppler shift in the spectral lines of Cepheids as they pulsated 
E)  by assuming that the Cepheids that appeared the brightest in the sky were closest to us
Section 19.4: The H-R Diagram and Cosmic Distances 
A)  by finding cepheids in star clusters whose distance was known in another way 
B)  because the star closest to us is a Cepheid variable and we know its distance 
C)  by noting that the period was related to the luminosity in all stars 
D)  by measuring the Doppler shift in the spectral lines of Cepheids as they pulsated 
E)  by assuming that the Cepheids that appeared the brightest in the sky were closest to us
Section 19.4: The H-R Diagram and Cosmic Distances

Question 6

An astronomical unit is:

Accepted Answer

A)  the distance to the nearest star 
B)  the distance covered by light in one year 
C)  the distance covered by light in one month 
D)  the time it takes for the solar system to turn once on its axis 
E)  the average distance between the Earth and the Sun 
A)  the distance to the nearest star 
B)  the distance covered by light in one year 
C)  the distance covered by light in one month 
D)  the time it takes for the solar system to turn once on its axis 
E)  the average distance between the Earth and the Sun

Question 7

The original definition of a meter was

Accepted Answer

A)  the distance from the extended index finger of the Emperor Napoleon to his nose 
B)  one thousandth of the distance from Paris to London 
C)  one billionth the distance from the Earth to the Sun 
D)  one ten-millionth of the distance from the Earth's equator to its pole 
E)  one thousandth the diameter of the town of Bayonne, New Jersey 
A)  the distance from the extended index finger of the Emperor Napoleon to his nose 
B)  one thousandth of the distance from Paris to London 
C)  one billionth the distance from the Earth to the Sun 
D)  one ten-millionth of the distance from the Earth's equator to its pole 
E)  one thousandth the diameter of the town of Bayonne, New Jersey

Question 8

Why do Cepheid variables have that strange name?

Accepted Answer

A)  they were discovered by an astronomer named George Cepheid 
B)  the first star discovered to be this kind of variable had the Latin name Cepheidus 
C)  the word Cepheid means changing in brightness in ancient Greek 
D)  the first such variable was discovered in a constellation called Cepheus 
E)  the astronomer who discovered them had a dog named Ceffie 
A)  they were discovered by an astronomer named George Cepheid 
B)  the first star discovered to be this kind of variable had the Latin name Cepheidus 
C)  the word Cepheid means changing in brightness in ancient Greek 
D)  the first such variable was discovered in a constellation called Cepheus 
E)  the astronomer who discovered them had a dog named Ceffie

Question 9

The apparent brightness of stars in general tells us nothing about their distances; we cannot assume that the dimmer stars are farther away. In order for the apparent brightness of a star to be a good indicator of its distance, all the stars would have to be:

Accepted Answer

A)  at the same distance 
B)  the same composition 
C)  the same luminosity 
D)  by themselves instead of in binary or double-star systems 
E)  a lot farther away than they presently are 
A)  at the same distance 
B)  the same composition 
C)  the same luminosity 
D)  by themselves instead of in binary or double-star systems 
E)  a lot farther away than they presently are

Question 10

How far away would a star with a parallax of 0.2 arcsec be from us?

Accepted Answer

A)  2 parsecs 
B)  5 parsecs 
C)  0.2 parsecs 
D)  0.5 parsecs 
E)  we need more information to answer this question 
A)  2 parsecs 
B)  5 parsecs 
C)  0.2 parsecs 
D)  0.5 parsecs 
E)  we need more information to answer this question

Question 11

An astronomer is interested in a galaxy called M31, the nearest galaxy that resembles our Milky Way. It is about 2 million lightyears away. Which technique would be able to give us a distance to this galaxy?

Accepted Answer

A)  parallax 
B)  radar reflections 
C)  period-luminosity relation for Cepheid variables 
D)  Kepler's laws 
E)  you can't fool me: there is no way at present to get a distance to an object so far away 
A)  parallax 
B)  radar reflections 
C)  period-luminosity relation for Cepheid variables 
D)  Kepler's laws 
E)  you can't fool me: there is no way at present to get a distance to an object so far away

Question 12

Which of the following will show the smallest parallax shift?

Accepted Answer

A)  the Moon 
B)  the planet Jupiter 
C)  the Sun 
D)  Proxima Centauri, the nearest star 
E)  the star 51 Pegasi, about 50 lightyears away
Section 19.3: Variable Stars: One Key to Cosmic Distances 
A)  the Moon 
B)  the planet Jupiter 
C)  the Sun 
D)  Proxima Centauri, the nearest star 
E)  the star 51 Pegasi, about 50 lightyears away
Section 19.3: Variable Stars: One Key to Cosmic Distances

Question 13

Kepler's Laws can give us the relative distance of objects in the solar system. To convert these relative distances into actual distances, we need to:

Accepted Answer

A)  measure the mass of the Sun 
B)  measure the size of the Earth 
C)  measure the distance directly to any object orbiting the Sun 
D)  measure the length of the year exactly 
E)  measure the exact time it takes for the Earth to spin once on its axis 
A)  measure the mass of the Sun 
B)  measure the size of the Earth 
C)  measure the distance directly to any object orbiting the Sun 
D)  measure the length of the year exactly 
E)  measure the exact time it takes for the Earth to spin once on its axis

Question 14

Astronomers must often know the distance to a star before they can fully understand its characteristics. Which of the following properties of a star typically requires a knowledge of distance before it can be determined?

Accepted Answer

A)  its luminosity 
B)  its radial velocity 
C)  its temperature 
D)  its apparent brightness 
E)  all of the above 
A)  its luminosity 
B)  its radial velocity 
C)  its temperature 
D)  its apparent brightness 
E)  all of the above

Question 15

To get the distance to a Cepheid variable star, astronomers must take several steps. Which of the following is NOT one of these steps?

Accepted Answer

A)  observe the star getting brighter and dimmer to establish that it varies 
B)  measure the period of variations by timing when the star is brightest and dimmest 
C)  estimate the apparent brightness of the star 
D)  measure the star's Doppler shift from its spectrum 
E)  apply the period-luminosity relationship 
A)  observe the star getting brighter and dimmer to establish that it varies 
B)  measure the period of variations by timing when the star is brightest and dimmest 
C)  estimate the apparent brightness of the star 
D)  measure the star's Doppler shift from its spectrum 
E)  apply the period-luminosity relationship

Question 16

What is the baseline that astronomers use to measure the parallax (the distance) of the nearest stars?

Accepted Answer

A)  the diameter of the Earth 
B)  the distance between observatories in Greenwich, England and Washington, DC 
C)  the distance between the Earth and the Moon 
D)  ½ the diameter of the Earth's orbit around the Sun 
E)  no one can measure parallax for the stars; only for planets in our solar system 
A)  the diameter of the Earth 
B)  the distance between observatories in Greenwich, England and Washington, DC 
C)  the distance between the Earth and the Moon 
D)  ½ the diameter of the Earth's orbit around the Sun 
E)  no one can measure parallax for the stars; only for planets in our solar system

Question 17

A type of star that has turned out to be extremely useful for measuring distances is

Accepted Answer

A)  the eclipsing binaries 
B)  the Cepheid variables 
C)  the main sequence stars 
D)  the white dwarf stars 
E)  the stars that lie in the constellation of Orion 
A)  the eclipsing binaries 
B)  the Cepheid variables 
C)  the main sequence stars 
D)  the white dwarf stars 
E)  the stars that lie in the constellation of Orion

Question 18

An astronomer is observing a single star (and one which does not vary) which she knows is located about 30 light-years away. What was the most likely method she or her colleagues used to obtain that distance?

Accepted Answer

A)  bouncing radar beams off the star 
B)  measuring the star's parallax 
C)  the period-luminosity relationship 
D)  Kepler's laws 
E)  Hubble's law 
A)  bouncing radar beams off the star 
B)  measuring the star's parallax 
C)  the period-luminosity relationship 
D)  Kepler's laws 
E)  Hubble's law

Question 19

To establish the scale of the solar system, we need to measure the distance to one object orbiting the Sun. Venus was first used for this purpose, but in the 1930's astronomers organized an international campaign to measure the distance to:

Accepted Answer

A)  Mars 
B)  the Moon 
C)  the asteroid Eros 
D)  Pluto because of its great distance from the Sun 
E)  Mercury
Section 19.2: Surveying the Stars 
A)  Mars 
B)  the Moon 
C)  the asteroid Eros 
D)  Pluto because of its great distance from the Sun 
E)  Mercury
Section 19.2: Surveying the Stars

Question 20

If an astronomer wants to find the distance to a star that is not variable and is located too far away for parallax measurements, she can:

Accepted Answer

A)  use the star's light curve 
B)  find the star's luminosity class from its spectrum and read the luminosity from an H-R diagram 
C)  use Kepler's laws as modified by Newton 
D)  search for planets around the star since it is much easier to get the distance to planets 
E)  only throw up her hands in desperation; there is no way to even estimate the distance to such a star 
A)  use the star's light curve 
B)  find the star's luminosity class from its spectrum and read the luminosity from an H-R diagram 
C)  use Kepler's laws as modified by Newton 
D)  search for planets around the star since it is much easier to get the distance to planets 
E)  only throw up her hands in desperation; there is no way to even estimate the distance to such a star

Exam 19: Celestial Distances

The higher the luminosity (intrinsic brightness) a Cepheid variable is,

Which of the following stars is a Cepheid variable?

If a star is 20 parsecs away, its parallax must be:

As astronomers use the term, the parallax of a star is

How did Henrietta Leavitt "calibrate" her period-luminosity relationship for Cepheid variable stars? In other words, how did she make the general idea into a numerical rule?

An astronomical unit is:

The original definition of a meter was

Why do Cepheid variables have that strange name?

The apparent brightness of stars in general tells us nothing about their distances; we cannot assume that the dimmer stars are farther away. In order for the apparent brightness of a star to be a good indicator of its distance, all the stars would have to be:

How far away would a star with a parallax of 0.2 arcsec be from us?

An astronomer is interested in a galaxy called M31, the nearest galaxy that resembles our Milky Way. It is about 2 million lightyears away. Which technique would be able to give us a distance to this galaxy?

Which of the following will show the smallest parallax shift?

Kepler's Laws can give us the relative distance of objects in the solar system. To convert these relative distances into actual distances, we need to:

Astronomers must often know the distance to a star before they can fully understand its characteristics. Which of the following properties of a star typically requires a knowledge of distance before it can be determined?

To get the distance to a Cepheid variable star, astronomers must take several steps. Which of the following is NOT one of these steps?

What is the baseline that astronomers use to measure the parallax (the distance) of the nearest stars?

A type of star that has turned out to be extremely useful for measuring distances is

An astronomer is observing a single star (and one which does not vary) which she knows is located about 30 light-years away. What was the most likely method she or her colleagues used to obtain that distance?

To establish the scale of the solar system, we need to measure the distance to one object orbiting the Sun. Venus was first used for this purpose, but in the 1930's astronomers organized an international campaign to measure the distance to:

If an astronomer wants to find the distance to a star that is not variable and is located too far away for parallax measurements, she can:

Science and the Universe: a Brief Tour

Observing the Sky: the Birth of Astronomy

Orbits and Gravity

Earth, Moon, and Sky

Radiation and Spectra

Astronomical Instruments

Other Worlds: an Introduction to the Solar System

Earth As a Planet

Cratered Worlds: the Moon and Mercury

Earthlike Planets: Venus and Mars

The Giant Planets

Rings, Moons, and Pluto

Comets and Asteroids: Debris of the Solar System

Cosmic Samples and the Origin of the Solar System

The Sun: a Garden-Variety Star

The Sun: a Nuclear Powerhouse

Analyzing Starlight

The Stars: a Celestial Census

Between the Stars

The Birth of Stars and the Discovery of Planets Outside the Solar System

Stars From Adolescence to Old Age

The Death of Stars

Black Holes and Curved Space-Time

The Milky Way Galaxy

Galaxies

Active Galaxies, Quasars, and Supermassive Black Holes

The Evolution and Distribution of Galaxies

The Big Bang

Life in the Universe

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