Astronomy flash cards for final! (including multiple choice answers!)

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Which of the following is a general difference between a planet and a star?
a)All planets are made of rock and all stars are made of gas.
b) Planets are brighter than stars.
c)Planets are larger than stars.
d)Stars glow in infrared and visible light, while planets glow only in the infrared.

d)Stars glow in infrared and visible light, while planets glow only in the infrared.

Our solar system consists of _________.
a)the Sun and several nearby stars, as well as the planets and other objects that orbit these stars
b) the Sun and the planets, and nothing else
c) a few hundred billion stars, bound together by gravity
d) the Sun and all the objects that orbit it

d) the Sun and all the objects that orbit it

Which of the following best describes what we mean by the universe?
a)a vast collection of stars that number as many as the grains of sand on all the beaches on Earth
b) all the galaxies in all the superclusters
c) our Milky Way Galaxy
d) the sum total of all matter and energy

d) the sum total of all matter and energy

What do astronomers mean by the Big Bang?
a)the explosion of a massive star at the end of its life
b) the event that marked the beginning of the expansion of the universe
c) the event that marked the birth of our solar system
d) a gigantic explosion that blew all the galaxies in the universe to smithereens

b) the event that marked the beginning of the expansion of the universe

What do we mean when we say that the universe is expanding?
a)Within galaxies, average distances between star systems are increasing with time.
b) Everything in the universe is gradually growing in size.
c) The statement is not meant to be literal; rather, it means that our knowledge of the universe is growing.
d) Average distances between galaxies are increasing with time.

d) Average distances between galaxies are increasing with time.

A television advertisement claiming that a product is light-years ahead of its time does not make sense because _________.
a)a light-year is an astronomically large unit, so a product could not possibly be so advanced
b) it doesn’t specify the number of light-years
c) light-years can only be used to talk about light
d) it uses "light-years" to talk about time, but a light-year is a unit of distance

d) it uses "light-years" to talk about time, but a light-year is a unit of distance

The term observable universe refers to _________.
a)the portion of the universe that can be seen by the naked eye
b) that portion of the universe that we can see in principle, given the current age of the universe
c)that portion of the universe that we have so far photographed through telescopes
d)the portion of the universe that is not hidden from view by, for example, being below the horizon

b) that portion of the universe that we can see in principle, given the current age of the universe

On a scale where the Sun is about the size of a grapefruit and the Earth is about 15 meters away, how far away are the nearest stars besides the Sun?
a)about the distance across 50 football fields
b) 100 meters
c) about the distance across the state of Delaware
d) about the distance across the United States

d) about the distance across the United States

If the 14 billion year history of the universe were compressed to one year, and "now" is exactly midnight December 31, approximately how long ago were your grandparents born?
a)0.15 second ago
b) 1 minute ago
c) 1 hour ago
d) 1 second ago

a)0.15 second ago

What is the "Raisin Cake model" intended to explain?
a)that every raisin in a raisin cake moves farther away from every other raisin: there is no special central raisin (and no special central galaxy)
b) that raisins, like galaxies, expand with the rest of the universe
c) that the universe heats up as it expands, just like the raisin cake heats and expands
d) that all the raisins in the cake move away from one central raisin, just as all galaxies are moving away from one special galaxy (ours)

a)that every raisin in a raisin cake moves farther away from every other raisin: there is no special central raisin (and no special central galaxy)

What do astronomers mean by a constellation?
a)A constellation is a group of stars that are all located in about the same place in space.
b)A constellation is any random grouping of stars in the sky.
c)A constellation is a region in the sky as seen from Earth.
d)A constellation is a group of stars related through an ancient story.

c)A constellation is a region in the sky as seen from Earth.

What is the ecliptic?
a)the path the Sun appears to trace around the celestial sphere each year
b) the path traced by the Moon’s shadow on Earth during a solar eclipse
c) a half-circle extending from your horizon due north, through your zenith, to your horizon due south
d) the Sun’s daily path from east to west in our sky

a)the path the Sun appears to trace around the celestial sphere each year

Which of the following celestial objects do NOT rise in the east and set in the west, as viewed from the Earth? (Assume that all of these objects are visible from your location on Earth, and that none of them are circumpolar.)
a)the Moon
b) stars
c) the Sun
d) galaxies
e) All of these objects rise in the east and set in the west.

e) All of these objects rise in the east and set in the west.

Which of the following statements does NOT use the term angular size or angular distance correctly?
a)The angular distance between those two houses in the distance is 30 degrees.
b) The angular distance between those two bright stars in the sky is about 2 meters.
c) The angular size of the Sun is about the same as that of the Moon.
d) You can use your outstretched hand against the sky to estimate angular sizes and angular distances.

b)The angular distance between those two bright stars in the sky is about 2 meters.

Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called _________.
a)celestial
b)seasonal
c) circumpolar
d) bright

c) circumpolar

If you are located in the Northern Hemisphere, which of the following correctly describes a relationship between the sky and your location?
a)The altitude of the celestial equator equals your latitude.
b) The altitude of the north celestial pole equals your longitude.
c) The altitude of the north celestial pole equals your latitude.
d) The longitude of the north celestial pole is circumpolar, and therefore crosses your zenith at the meridian.

c) The altitude of the north celestial pole equals your latitude.

Which of the following best describes why we have seasons on Earth?
a)The tilt of Earth’s axis causes the Northern Hemisphere to be closer to the Sun than the Southern Hemisphere in summer, and visa versa in winter.
b) The varying speed of Earth in its orbit around the Sun gives us summer when we are moving fastest and winter when we are moving slowest.
c) The tilt of Earth’s axis causes different portions of Earth to receive more or less direct sunlight at different times of year.
d) Earth’s elliptical orbit means we are closer to the Sun and therefore receive more intense sunlight at some times of year than at others.

c) The tilt of Earth’s axis causes different portions of Earth to receive more or less direct sunlight at different times of year.

If we have a new moon today, when we will have the next full moon?
a) in about a month
b) in about 2 weeks
c) in about 6 months
d) in about 1 week

b) in about 2 weeks

We cannot see a new moon in our sky because _________.
a)it is above the horizon during the daytime
b) no sunlight is illuminating the Moon
c) a new moon is quite near the Sun in the sky
d) it is obscured by Earth’s shadow

c) a new moon is quite near the Sun in the sky

Lunar eclipses can occur only during a _________.
a)new moon
b)third quarter moon
c)first quarter moon
d)full moon

d)full moon

During the time that a planet is in its period of apparent retrograde motion, _________.
a)the planet is getting closer to the Sun in its orbit
b) the planet moves backwards (clockwise as viewed from above Earth’s north pole) in its orbit of the Sun
c)over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars
d) the planet appears to rise in the west and set in the east, rather than the usual rising in the east and setting in the west

c)over many days or weeks, the planet moves westward relative to the stars, rather than the usual eastward relative to the stars

How would a star’s parallax change as its distance from Earth increases?
a)The parallax shift decreases as the star’s distance from Earth increases.
b) The parallax shift does not change; it is independent of the star’s distance from Earth.
c) The parallax shift increases as the star’s distance from Earth increases.

a)The parallax shift decreases as the star’s distance from Earth increases.

What practical value did astronomy offer to ancient civilizations?
a)It helped them understand our cosmic origins.
b)It helped them find uses for ancient structures like Stonehenge.
c)It helped them keep track of time and seasons, and it was used by some cultures for navigation.
d)It allowed them to predict eclipses with great accuracy.

c)It helped them keep track of time and seasons, and it was used by some cultures for navigation.

Scientific thinking is _________. a)an ancient mode of thinking first invented in Egypt
b) completely different from any other type of thinking
c) a difficult process that only a handful of people can do well
d) based on everyday ideas of observation and trial-and-error experiments

d) based on everyday ideas of observation and trial-and-error experiments

The ancient Greeks get a lot of attention for their contributions to science because _________.
a)the books of every other culture were lost in the destruction of the library of Alexandria
b) they were the only ancient culture that kept written records of their astronomical observations
c) they were the first people known to try to explain nature with models based on reason and mathematics, without resort to the supernatural
d) they were the first people to realize that Earth is a planet orbiting the Sun

c) they were the first people known to try to explain nature with models based on reason and mathematics, without resort to the supernatural

What do we mean by a geocentric model of the universe?
a)a model of the Milky Way Galaxy that has our solar system located at its center
b)the name given to sphere-shaped models that show all the constellations as they appear in our sky on the celestial sphere
c) a model designed to explain what we see in the sky while having Earth located in the center of the universe
d) a model designed to explain what we see in the sky while having Earth orbit the Sun

c) a model designed to explain what we see in the sky while having Earth located in the center

What was the Ptolemaic model?
a)an Earth-centered model of planetary motion published by Ptolemy
b) the Earth-centered model of the cosmos in which Earth was surrounded by seven perfect spheres, one each for the Sun, Moon, Mercury, Venus, Mars, Jupiter, and Saturn
c) a Sun-centered model of planetary motion published by Ptolemy
d) the first scientific model to successfully predict solar and lunar eclipses

a)an Earth-centered model of planetary motion published by Ptolemy

The great contribution of Nicholas Copernicus was to _________.
a)discover the law of gravity
b) discover the laws of planetary motion
c) create a detailed model of our solar system with the Sun rather than Earth at the center
d) prove that Earth is not the center of the universe

c) create a detailed model of our solar system with the Sun rather than Earth at the center

The great contribution of Tycho Brahe was to _________.
a)discover that planets orbit the Sun in elliptical orbits with varying speed
b) observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion
c) discover four moons orbiting Jupiter, thereby lending strong support to the idea that Earth is not the center of the universe

b) observe planetary positions with sufficient accuracy so that Kepler could later use the data to discover the laws of planetary motion

Which of the following was NOT observed by Galileo?
a)phases of Venus
b) mountains and valleys on the Moon
c) stellar parallax
d) four moons orbiting Jupiter

c) stellar parallax

Which of the following statements about an ellipse is NOT true?
a)A circle is considered to be a special type of ellipse.
b) The focus of an ellipse is always located precisely at the center of the ellipse.
c) An ellipse with a large eccentricity looks much more elongated (stretched out) than an ellipse with a small eccentricity.
d) The semimajor axis of an ellipse is half the length of the longest line that you can draw across an ellipse.

b) The focus of an ellipse is always located precisely at the center of the ellipse.

Which of the following claims can be tested by scientific means?
a)Blue is the best color for walls.
b) God exists.
c) People born when the Sun is in the constellation of Leo are more financially successful than other people.
d) The final thoughts of Abraham Lincoln were about the fate of his country.

c) People born when the Sun is in the constellation of Leo are more financially successful than other people.

In science, a broad idea that has been repeatedly verified so as to give scientists great confidence that it represents reality is called _________.
a)a Ptolemaic model
b) a hypothesis
c) a paradigm
d) a theory

d) a theory

The acceleration of gravity on Earth is approximately 10 m/s2 (more precisely, 9.8 m/s2). If you drop a rock from a tall building, about how fast will it be falling after 3 seconds?
a)20 m/s
b) 10 m/s
c) 30 m/s2
d) 30 m/s
e) 10 m/s2

d) 30 m/s

Suppose you lived on the Moon. Which of the following would be true?
a)Your mass would be less than your mass on Earth, but your weight would be the same as it is on Earth.
b) Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth.
c)Both your weight and your mass would be less than they are on Earth.

b) Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth.

Which of the following describes a speed, according to an astronomer?
a)40 revolutions per hour
b) 5 light-years
c) 20 meters per second, headed north
d) 10 light-years per 1 million years

d) 10 light-years per 1 million years

Which of the following statements is NOT one of Newton’s Laws of Motion?
a)The rate of change of momentum of an object is equal to the net force applied to the object.
b) For any force, there always is an equal and opposite reaction force.
c) In the absence of a net force acting upon it, an object moves with constant velocity.
d) What goes up must come down.

d) What goes up must come down.

Which of the following examples describes a situation where a car is experiencing a net force?
a)The car is making a gradual turn.
b) The car is floating on a stationary boat.
c) The car is moving at constant speed.
d) The car is stopped on a hill.

a)The car is making a gradual turn.

Suppose that two objects collide. Which of the following things is NOT the same both before and after the collision?
a) the total momentum of the objects
b) the total energy of the objects
c) the total angular momentum of the objects
d) the total temperature of the objects

d) the total temperature of the objects

When a spinning ice skater pulls in his arms, he spins faster because _________
a).there is less friction with the air
b) his angular momentum must be conserved, so reducing his radius must increase his speed of rotation
c) there exists an unbalanced reaction force
d) there is less friction with the ice

b) his angular momentum must be conserved, so reducing his radius must increase his speed of rotation

What does temperature measure?
a) the average mass of particles in a substance
b) the average kinetic energy of particles in a substance
c) the total potential energy of particles in a substance
d) the total amount of heat in a substance

b) the average kinetic energy of particles in a substance

According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them _________.
a)decreases by a factor of 3
b) increases by a factor of 3
c) increases by a factor of 9
d) decreases by a factor of 9

d) decreases by a factor of 9

Why is Newton’s version of Kepler’s third law so useful to astronomers?
a)It allows us to calculate distances to distant objects.
b) It can be used to determine the masses of many distant objects.
c) It tells us that more-distant planets orbit the Sun more slowly.
d)It explains why objects spin faster when they shrink in size.

b) It can be used to determine the masses of many distant objects.

Which statement must be true in order for a rocket to travel from Earth to another planet?
a) It must be launched from space, rather than from the ground.
b) It must have very large engines.
c) It must attain escape velocity from Earth.
d) It must carry a lot of extra fuel.

c) It must attain escape velocity from Earth.

Approximately where is it currently high tide on Earth?a)Wherever it is currently noon.
b)Anywhere that ocean water laps upon the shore.
c) On the portion of Earth facing directly toward the Moon and on the portion of Earth facing directly away from the Moon.
d) Only on the portion of the Earth facing directly toward the Moon.

c) On the portion of Earth facing directly toward the Moon and on the portion of Earth facing directly away from the Moon.

Which forms of light are lower in energy and frequency than the light that our eyes can see? a)visible light
b) infrared and radio
c) infrared and ultraviolet
d) ultraviolet and X ray

b) infrared and radio

Suppose you watch a leaf bobbing up and down as ripples pass it by in a pond. You notice that it does two full up and down bobs each second. Which statement is true of the ripples on the pond?
a)They have a frequency of 4 hertz.
b) They have a wavelength of two cycles per second.
c) They have a frequency of 2 hertz.
d) We can calculate the wavelength of the ripples from their frequency.

c) They have a frequency of 2 hertz.

Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon?
a)its temperature
b) the chemical composition of the object that emitted it
c) its wavelength and energy
d) its acceleration

c) its wavelength and energy

Which of the following best describes the fundamental difference between two different chemical elements (such as oxygen and carbon)?
a)They have different names.
b) They have different numbers of electrons.
c) They have different atomic mass numbers.
d) They have different numbers of protons in their nucleus.

d) They have different numbers of protons in their nucleus.

If we say that a material is opaque to ultraviolet light, we mean that it _________.
a)emits ultraviolet light
b) transmits ultraviolet light
c) reflects ultraviolet light
d) absorbs ultraviolet light

d) absorbs ultraviolet light

Suppose you look at a spectrum of visible light by looking through a prism or diffraction grating. How can you decide whether it is an emission line spectrum or an absorption line spectrum?
a)An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.
b)An emission line spectrum consists of a long bright line, while an absorption line spectrum consists of a long dark line.
c) The only way to decide is to make a graph of the intensity of the light at every wavelength, and then analyze the graph carefully.
d) The emission line spectrum is produced by electrons jumping up in energy level, while the absorption line spectrum is produced by electrons jumping down in energy level.

a)An emission line spectrum consists of bright lines on a dark background, while an absorption line spectrum consists of dark lines on a rainbow background.

Thermal radiation is defined as _________.
a)radiation that is felt as heat
b) radiation with a spectrum whose shape depends only on the temperature of the emitting object
c) radiation produced by an extremely hot object
d)radiation in the form of emission lines from an object

b) radiation with a spectrum whose shape depends only on the temperature of the emitting object

According to the laws of thermal radiation, hotter objects emit photons with _________.
a)a lower average frequency
b) a lower average energy
c) a higher average speed
d) a shorter average wavelength

d) a shorter average wavelength

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?
a)the wavelengths of spectral lines in the star’s spectrum
b) the Doppler shift of the star’s spectrum
c) the peak energy of the star’s thermal radiation
d) whether the star’s spectrum has more emission lines or more absorption lines

a)the wavelengths of spectral lines in the star’s spectrum

The spectra of most galaxies show redshifts. This means that their spectral lines _________.
a)have a higher intensity in the red part of the spectrum
b) have wavelengths that are shorter than normal
c) have wavelengths that are longer than normal
d) always are in the red part of the visible spectrum

c) have wavelengths that are longer than normal

What does angular resolution measure?
a)the brightness of an image
b) the angular size of the smallest features that the telescope can see
c) the number of electromagnetic waves captured by an image
d) the size of an image

b) the angular size of the smallest features that the telescope can see

What is the angular resolution of the human eye?
a)about 1 arcminute, or 1/60 of a degree
b) about 1 arcsecond (1/3600 of a degree)
c) about 1 milliarcsecond
d) about 1 degree

a)about 1 arcminute, or 1/60 of a degree

Which of the following statements best describes the two principle advantages of telescopes over eyes?
a)Telescopes can collect far more light with far better angular resolution.
b)Telescopes have much more magnification and better angular resolution.
c) Telescopes collect more light and are unaffected by twinkling.
d) Telescopes can collect far more light with far greater magnification.

a)Telescopes can collect far more light with far better angular resolution.

Which of the following statements best describes the difference between a refracting telescope and a reflecting telescope?
a)A refracting telescope produces refracted images while a reflecting telescope produces reflected images.
b) A refracting telescope uses a transparent glass lens to focus light while a reflecting telescope uses a mirror to focus light.
c) Reflecting telescopes make much clearer images than can refracting telescopes of the same size.
d) It is much easier to make a large refracting telescope than a large reflecting telescope.

b) A refracting telescope uses a transparent glass lens to focus light while a reflecting telescope uses a mirror to focus light.

What do we mean by the diffraction limit of a telescope?
a)It is the maximum size to which any telescope can be built.
b) It describes the farthest distance to which the telescope can see.
c)It describes the maximum exposure time for images captured with the telescope.
d) It is the angular resolution the telescope could achieve if nothing besides the size of its light-collecting area affected the quality of its images.

d) It is the angular resolution the telescope could achieve if nothing besides the size of its light-collecting area affected the quality of its images.

Suppose you want to determine the chemical composition of a distant planet or star. Which of the following will be most useful to have?
a)high turbulence
b) high spectral resolution
c) high angular resolution
d) a radio telescope

b) high spectral resolution

Which of the following is always true about images captured with X-ray telescopes?
a) They are always shown with colors that are NOT the true colors of the objects that were photographed.
b) They always have very high angular resolution.
c) They show us light with extremely long wavelengths compared to the wavelengths of visible light.
d)They always are made with adaptive optics.

a) They are always shown with colors that are NOT the true colors of the objects that were photographed.

What do astronomers mean by light pollution?
a)Light pollution is light from human sources that makes it difficult to see the stars at night.
b)Light pollution means contamination of light caused by chemicals in Earth’s atmosphere.
c) Light pollution is a type of air pollution created by lightweight gases such as hydrogen and helium.
d) Light pollution is a term used to describe the appearance of the sky in regions that are crowded with stars.

a)Light pollution is light from human sources that makes it difficult to see the stars at night.

Which of the following effects is caused by atmospheric turbulence?
a)magnification of images
b) twinkling of stars
c) diffraction of light
d) light pollution

b) twinkling of stars

Which of the following wavelength regions can be studied with telescopes on the ground?
a)infrared, visible, and ultraviolet light
b) radio, visible, and very limited portions of the infrared and ultraviolet regions
c) all light with wavelengths longer than ultraviolet wavelengths
d) all light with wavelengths shorter than infrared wavelengths

b) radio, visible, and very limited portions of the infrared and ultraviolet regions

Suppose you view the solar system from high above Earth’s North Pole. Which of the following statements about planetary orbits will be true?
a)The inner planets orbit the Sun counterclockwise while the outer planets orbit the Sun clockwise.
b) All the planets except Uranus orbit the Sun counterclockwise; Uranus orbits in the opposite direction.
c) The inner planets orbit the Sun clockwise while the outer planets orbit the Sun counterclockwise.
d) All the planets orbit counterclockwise around the Sun.

d) All the planets orbit counterclockwise around the Sun.

When we say that jovian planets contain significant amounts of hydrogen compounds, we mean all the following chemicals EXCEPT ______.
a)methane
b)ammonia
c) carbon dioxide
d) water

c) carbon dioxide

What is the Kuiper belt?
a)a region of the solar system that extends almost a fourth of the way to the nearest stars and contains a trillion comets with orbits going in all directions around the Sun
b) a region of the solar system beginning just beyond the orbit of Neptune that contains many icy comets
c) the most prominent ring of Saturn that is visible in photographs
d) a technical name for the asteroid belt

b) a region of the solar system beginning just beyond the orbit of Neptune that contains many icy comets

What is the Oort cloud?
a)It’s not really a cloud at all, but rather refers to the trillion or so comets thought to orbit the Sun at great distances.
b) It is a giant storm in the atmosphere of Saturn.
c) It is another name for the cloud of gas from which our solar system was born.
d) It is a great cloud of gas that resides far beyond the orbit of Pluto.

a)It’s not really a cloud at all, but rather refers to the trillion or so comets thought to orbit the Sun at great distances.

Which of the following statements about our Sun is NOT true?
a)The Sun is made mostly of hydrogen and helium.
b) The Sun contains more than 99 percent of all the mass in our solar system.
c) The Sun is a star.
d) The Sun’s diameter is about five times that of Earth.

d) The Sun’s diameter is about five times that of Earth.

The planet in our solar system with the highest average surface temperature is __________.
a)Earth
b) Neptune
c) Mercury
d) Venus

d) Venus

Which jovian planet does NOT have rings?
a)Neptune
b) All the jovian planets have rings.
c) Uranus
d) Jupiter

b) All the jovian planets have rings.

Which of the following statements about Pluto is true?
a)It is the largest known object that is considered to be a dwarf planet.
b) Its mass is a little less than Earth’s mass.
c)It is orbited by only one moon.
d) It has more in common with comets in the Kuiper belt than it does with terrestrial planets like Earth.

d) It has more in common with comets in the Kuiper belt than it does with terrestrial planets like Earth.

Robotic spacecraft have different levels of complexity, which contributes to overall cost. Which of the following types of missions are likely to be the most expensive?
a)lander
b) orbiters
c) flybys
d) sample return missions

b) orbiters

In essence, the nebular theory holds that _________.
a) our solar system formed from the collapse of an interstellar cloud of gas and dust
b)nebulae are clouds of gas and dust in space
c) The nebular theory is a discarded idea that imagined planets forming as a result of a near-collision between our Sun and another star.
d) the planets each formed from the collapse of its own separate nebula

a) our solar system formed from the collapse of an interstellar cloud of gas and dust

How does the diameter of the disk of the Milky Way Galaxy compare to its thickness?
a)The diameter and thickness are roughly equal.
b)The diameter is about 100,000 times as great as the thickness.
c) The diameter is about 10 times as great as the thickness.
d) The diameter is about 100 times as great as the thickness.

d) The diameter is about 100 times as great as the thickness.

The Sun’s location in the Milky Way Galaxy is _________.
a)very near the galactic center
b) in the halo of the galaxy, about 28,000 light-years above the galactic disk
c) in the galactic disk, roughly halfway between the center and the outer edge of the disk
d) at the very outer edge of the galactic disk

c) in the galactic disk, roughly halfway between the center and the outer edge of the disk

How do disk stars orbit the center of the galaxy?
a)They follow orbits that move up and down through the disk, typically taking them about 50,000 light-years above and below the disk on each orbit.
b) They follow spiral paths along the spiral arms.
c) They have orbits randomly inclined and in different directions relative to the galactic center.
d) They all orbit in roughly the same plane and in the same direction.

d) They all orbit in roughly the same plane and in the same direction.

How do we know the total mass of the Milky Way Galaxy that is contained within the Sun’s orbital path?
a)by counting the number of stars visible in this region of the galaxy
b) by estimating the amount of gas and dust in between the stars
c) by using the law of conservation of angular momentum to calculate the orbital speeds of nearby stars
d) by applying Newton’s version of Kepler’s third law (or the equivalent orbital velocity law) to the Sun’s orbit around the center of the galaxy

d) by applying Newton’s version of Kepler’s third law (or the equivalent orbital velocity law) to the Sun’s orbit around the center of the galaxy

What do we mean by the star-gas-star cycle?
a)It is the continuous recycling of gas in the galactic disk between stars and the interstellar medium.
b) It is the idea that stars in close binary systems can exchange gas with one another.
c)It describes the orbits of the stars and interstellar medium around the center of the galaxy.
d) It is the set of nuclear reactions by which heavy elements are produced in the cores of massive stars.

a)It is the continuous recycling of gas in the galactic disk between stars and the interstellar medium.

Which of the following models best explains why our galaxy has spiral arms?
a)The spiral arms are a wave of star formation caused by a wave of density propagating outward through the disk of the galaxy.
b) The spiral arms are composed of groups of stars that are bound together by gravity and therefore always stay together as the galaxy rotates.
c) The spiral arms were imprinted on the galaxy at its birth. Ever since, like a coiling rope, the spiral arms have been wound tighter with each galactic rotation.
d) No model can explain the existence of the arms, which rotate with the galaxy like the fins of a giant pinwheel toy.

a)The spiral arms are a wave of star formation caused by a wave of density propagating outward through the disk of the galaxy.

What do halo stars do differently from disk stars?
a)They remain stationary, quite unlike disk stars that orbit the galactic center.
b)They orbit the galactic center with many different inclinations, while disk stars all orbit in nearly the same plane.
c)They orbit the center of the galaxy at much lower speeds than disk stars.
d) Halo stars explode as supernovae much more frequently than disk stars.

b)They orbit the galactic center with many different inclinations, while disk stars all orbit in nearly the same plane.

Where does most star
formation occur in the Milky Way Galaxy?
a)within the halo
b) in the central bulge
c) in the spiral arms
d) everywhere throughout the galactic disk

c) in the spiral arms

Based on observations, which of the following statements about stars in the Milky Way is generally true?
a)The older the star, the faster its orbital speed.
b) The older the star, the lower its abundance of heavy elements.
c) The older the star, the bluer its color.
d) The less massive the star, the older it is.
e)The younger the star, the higher its mass.

b) The older the star, the lower its abundance of heavy elements.

What kind of object do we think lies in the center of the Milky Way Galaxy?
a)a gigantic X-ray binary system
b) a dense cluster of young, hot stars
c) a 3 to 4 million solar mass black hole
d) an enormous collection of dark matter, explaining why we detect no light at all from the galactic center

c) a 3 to 4 million solar mass black hole

Which of the following best describes the status of the Milky Way in our local group of galaxies?
a)It is quite average among the galaxies in the group.
b) It is by far the largest galaxy in the group.
c) It is one of the two largest galaxies in the group.
d) It is one of about a dozen large spiral galaxies in the group.

c) It is one of the two largest galaxies in the group.

Overall, what is our most accurate technique for measuring the distance to a nearby star?
a)radar ranging
b) main-sequence fitting
c) Hubble’s law
d) stellar parallax

d) stellar parallax

A standard candle is _________.
a)a light source of known luminosity
b) another name for a barred-spiral galaxy
c) a 7-cm-long wax candle
d) another name for a main-sequence star

a)a light source of known luminosity

What is main-sequence fitting?
a)a method for determining the age of a star cluster
b) a method for determining the distance to a star cluster by assuming that its main sequence should line up with the main sequence on a standard H-R diagram
c) a way of constructing an H-R diagram by plotting the surface temperatures and luminosities of stars
d) a way of forcing stars to fit into a standard main sequence, even when they have some unusual characteristics

b) a method for determining the distance to a star cluster by assuming that its main sequence should line up with the main sequence on a standard H-R diagram

What is a Cepheid variable?
a)a type of galaxy that varies in its light output
b) a main sequence star of spectral type B5
c) a type of very luminous star that makes an excellent standard candle
d) a bright source of variable X-ray emission, thought to harbor a supermassive black hole

c) a type of very luminous star that makes an excellent standard candle

You observe the peak brightnesses of two white dwarf supernovae. Supernova A is only one-quarter as bright as Supernova B. What can you say about their relative distances?
a)Supernova A is twice as far away as Supernova B.
b) Supernova A is four times as far away as Supernova B.
c) Supernova B is four times as far away as Supernova A.
d) Supernova B is twice as far away as Supernova A.
d) We can’t say anything about their relative distances because we do not have enough information.

a)Supernova A is twice as far away as Supernova B.

What does Hubble’s law tell us?
a)The faster a spiral galaxy’s rotation speed, the more luminous it is.
b) For every force, there is an equal and opposite reaction force.
c) The more distant a galaxy, the faster it is moving away from us.
d) The longer the period of a Cepheid variable, the greater its luminosity.

c) The more distant a galaxy, the faster it is moving away from us.

Spectral lines from Galaxy B are redshifted from their rest wavelengths twice as much as the spectral lines from Galaxy B. According to Hubble’s law, what can you say about their approximate relative distances?
a)Galaxy B is four times as far as Galaxy A.
b)Galaxy B is twice as far as Galaxy A.
c) There is not enough information to say—you need to know Hubble’s constant to answer this question.
d) Galaxy A is four times as far as Galaxy B.
Galaxy A is twice as far as Galaxy B.

b)Galaxy B is twice as far as Galaxy A.

Current estimates place the age of the universe at about ______.
a)10 billion years
b) 10 million years
c) 14 billion years
d) 4.5 billion years

c)14 billion years

If we say that a galaxy has a lookback time of 1 billion years, we mean that _________.
a)its light traveled through space for 1 billion years to reach us
b) it is now 1 billion light-years away
c) it was 1 billion light-years away when the light left the galaxy
d) it is 400 million years old

a)its light traveled through space for 1 billion years to reach us

Which of the following is an important starting assumption in models of galaxy formation?
a)Galaxies form first, then black holes.
b) Some regions in the universe start out denser than others.
c)All galaxies start out as spiral galaxies.
d) Black holes form first, seeding the formation of galaxies.

b) Some regions in the universe start out denser than others.

According to observations, what type of galaxy was much more common when the universe was 2 billion years old than it is today?
a)irregular galaxies
b) We can’t say, because we are living at a time when the universe is 14 billion years old, not 2 billion years.
c)elliptical galaxies
d) spiral galaxies

a)irregular galaxies

Collisions between galaxies typically unfold over a period of ______.
a)hundreds of millions of years
b) several months
c) several days
d) thousands of years

a)hundreds of millions of years

Why are collisions between galaxies more likely than collisions between stars within a galaxy?
a)Relative to their sizes, galaxies are closer together than stars.
b) Galaxies travel through space much faster than stars.
c)Galaxies are much larger than stars.
d) Galaxies have higher redshifts than stars.

a)Relative to their sizes, galaxies are closer together than stars.

Current understanding holds that a galaxy’s type (spiral, elliptical, or irregular) ______.
a)may be either a result of the mass of the protogalactic cloud that formed it or the result of the heavy element abundance in that cloud
b)is always determined by the angular momentum of the protogalactic cloud that formed it
c)may be either the result of conditions in the protogalactic cloud that formed it or the result of later interactions with other galaxies
d) is determined by whether the galaxy is located in a cluster where collisions are likely or outside a cluster where collisions are less likely

c)may be either the result of conditions in the protogalactic cloud that formed it or the result of later interactions with other galaxies

The distinguishing feature of a starburst galaxy is _________.
a)a very large luminosity compared to the total luminosity of the Milky Way
b) strong radio emission from "lobes" of material well outside the visible boundaries of the galaxy
c) a rate of star formation that may be 100 or more times greater than that in the Milky Way
d) the presence of an unusually large number of binary star systems containing X-ray bursters

c) a rate of star formation that may be 100 or more times greater than that in the Milky Way

The unusually bright centers found in some galaxies are called ______.
a) active galactic nuclei
b) supermassive black holes
c) starbursts
d) halos

a) active galactic nuclei

According to current understanding, what is a quasar?
a)an active galactic nucleus that is particularly bright
b) a very large galaxy thought to be formed by the merger of several smaller galaxies, typically found in the center of a galaxy cluster
c) a galaxy with an unusually high rate of star formation
d) any object with an extremely large redshift

a)an active galactic nucleus that is particularly bright

Which of the following phenomena is probably NOT related to the presence of a supermassive black hole?
a)quasars
b) the presence of globular clusters in the halos of galaxies
c)the huge jets seen emerging from the centers of some galaxies
d) the radio emission from radio galaxies

b) the presence of globular clusters in the halos of galaxies

The best evidence for the existence of supermassive black holes is __________.
a)very high orbital velocities in a very compact region
b) large quantities of high-energy emission, such as X-rays and gamma rays, and radio emission from relativistic electrons
c) huge dark regions in the centers of galaxies, where black holes have been sucking in the galaxy from the inside out
d) evidence for jet velocities that approach the speed of light

a)very high orbital velocities in a very compact region

What happens when a particle of matter meets its corresponding antiparticle of antimatter?
a)They fuse to make a heavier particle.
b) The combined mass of the two particles is completely transformed into energy (photons).
c) The question makes no sense, since antimatter does not really exist.
d) They can form a complete atom.

b) The combined mass of the two particles is completely transformed into energy (photons).

What happens to gas as it freely expands?
a)It gets more dense and heats.
b)It gets more dense and cools.
c) It gets less dense and cools.
d) It gets less dense and heats.

c) It gets less dense and cools.

A "GUT" (grand unified theory) refers to theories that _________.
a)unify the electromagnetic and weak nuclear forces
b) unify all four fundamental forces together
c) unify gravity with the strong and weak nuclear forces
d) unify the strong force with the electromagnetic and weak nuclear forces

d) unify the strong force with the electromagnetic and weak nuclear forces

What do we mean by inflation?
a)the expansion of the universe that we still observe today
b) the increase in costs of doing cosmological observations
c) a sudden and extremely rapid expansion of the universe that occurred in a tiny fraction of a second during the universe’s first second of existence
d) the sudden release of photons when a particle and antiparticle annihilate one another

c) a sudden and extremely rapid expansion of the universe that occurred in a tiny fraction of a second during the universe’s first second of existence

Which statement about the cosmic microwave background is NOT true?
a)With the exception of very small variations, it appears essentially the same in all directions in which we look into space.
b) Its spectrum corresponds to a temperature of just under 3 degrees above absolute zero.
c) It is thought to be radiation that began its journey to our telescopes when the universe was about 380,000 years old.
d) It is the result of a mixture of radiation from many independent sources, such as stars and galaxies.

d) It is the result of a mixture of radiation from many independent sources, such as stars and galaxies.

In the past, the temperature of the universe was _____.
a)cooler than it is today
b) hotter than it is today
c) absolute zero (0 K)
d) 3 K

b) hotter than it is today

The Big Bang theory is supported by two major lines of evidence that alternative models have not successfully explained. What are they?

a) (1) The theory predicts the existence of and the specific characteristics of the observed cosmic microwave background; (2) the theory correctly predicts the observed overall chemical composition of the primeval universe.
b)(1) The theory predicts the episode of inflation that we think occurred in the early universe; (2) the theory predicts the existence of large quantities of dark matter.
c) (1) The theory correctly predicts that the universe should be expanding; (2) the theory correctly predicts the observed ratio of spiral to elliptical galaxies in the universe.
d)(1) The theory correctly predicts that the universe should be expanding; (2) the theory predicts the existence of and the specific characteristics of the observed cosmic microwave background.

a) (1) The theory predicts the existence of and the specific characteristics of the observed cosmic microwave background; (2) the theory correctly predicts the observed overall chemical composition of the primeval universe.

Which of the following observations cannot be explained by the Big Bang theory unless we assume that an episode of inflation occurred?
a)the existence of the cosmic microwave background
b) the fact that the universe is expanding
c) the fact that about 25 percent of the ordinary matter in the universe consists of helium
d) the fact that the temperature of the cosmic microwave background is almost the same everywhere

d) the fact that the temperature of the cosmic microwave background is almost the same everywhere

Which of the following statements can NOT be tested by science today?
a)Our universe is flat.
b)The universe is 14 billion years old.
c)The expansion of the universe is now accelerating.
d) Prior to the Planck time, our universe emerged from another universe.

d) Prior to the Planck time, our universe emerged from another universe.

Which of the following best summarizes what we mean by dark matter?
a) matter that we have identified from its gravitational effects but that we cannot see in any wavelength of light
B)matter that may inhabit dark areas of the cosmos where we see nothing at all
c)matter consisting of black holes
d) matter for which we have theoretical reason to think it exists, but no observational evidence for its existence

a) matter that we have identified from its gravitational effects but that we cannot see in any wavelength of light

Which of the following best summarizes what we mean by dark energy?
a)It is the energy contained in dark matter.
b) It is a type of energy that is associated with the "dark side" of the force that rules the cosmos.
C) It is the energy of black holes.
D) It is a name given to whatever is causing the expansion of the universe to accele

D) It is a name given to whatever is causing the expansion of the universe to accele

What is a rotation curve?
a)a graph showing how orbital velocity depends on distance from the center for a spiral galaxy
b) a graph that shows a galaxy’s mass on the vertical axis and size on the horizontal axis
c) a precise description of the shape of a star’s orbit around the center of the Milky Way Galaxy
d) a curve used to decide whether a star’s orbit places it in the disk or the halo of a spiral galaxy

a)a graph showing how orbital velocity depends on distance from the center for a spiral galaxy

What do we mean when we say that the rotation curve for a spiral galaxy is "flat"?
a)All the galaxy’s mass is concentrated in its flat, gaseous disk.
b) Gas clouds orbiting far from the galactic center have approximately the same orbital speed as gas clouds located further inward.
c)The disk of a spiral galaxy is quite flat rather than spherical like the halo.
d)The amount of light emitted by stars at different distances is about the same throughout the galaxy.

b) Gas clouds orbiting far from the galactic center have approximately the same orbital speed as gas clouds located further inward.

Which of the following is NOT one of the three main strategies used to measure the mass of a galaxy cluster?
a)studying X-ray emission from hot gas inside the cluster
b) measuring the temperatures of stars in the halos of the galaxies
c) observing how the cluster bends light from galaxies located behind it
d) measuring the speeds of galaxies orbiting the cluster’s center

b) measuring the temperatures of stars in the halos of the galaxies

Which of the following statements best summarizes current evidence concerning dark matter in individual galaxies and in clusters of galaxies?
a)Dark matter is present in individual galaxies, but there is no evidence that it can exist between the galaxies in a cluster.
b) Within individual galaxies, dark matter is always concentrated near the galactic center, and within clusters it is always concentrated near the cluster center.
c)Dark matter is the dominant form of mass in both clusters and in individual galaxies.
d) Dark matter is present between galaxies in clusters, but not within individual galaxies.

c)Dark matter is the dominant form of mass in both clusters and in individual galaxies.

Measuring the amount of deuterium in the universe allows us to set a limit on _________.
a)the total amount of mass in the universe
b) the current age of the universe
c) the acceleration of the universe
d) the density of ordinary (baryonic) matter the universe

d) the density of ordinary (baryonic) matter the universe

What do we mean when we say that particles such as neutrinos or WIMPs are weakly interacting?
a)The light that they emit is so weak that it is undetectable to our telescopes.
b) They respond to the weak force but not to the electromagnetic force, which means they cannot emit light.
c) They interact with other matter only through the weak force and not through gravity or any other force.
d) They are only weakly bound by gravity, which means they can fly off and escape from galaxies quite easily.

b) They respond to the weak force but not to the electromagnetic force, which means they cannot emit light.

Which of the following best sums up current scientific thinking about the nature of dark matter?
a)Dark matter probably does not really exist, and rather indicates a fundamental problem in our understanding of gravity.
b) About 90 percent of dark matter consists of ordinary matter in the halo of the galaxy, and of the other 10 percent of WIMPs.
c)Most dark matter probably consists of weakly interacting particles of a type that we have not yet identified.
d) There is no longer any doubt that dark matter is made mostly of WIMPs.

c)Most dark matter probably consists of weakly interacting particles of a type that we have not yet identified.

The critical density of the universe is the _______.
a) average density the universe would need for gravity to someday halt the current expansion if dark energy did not exist
b) density of water
c)density of dark matter in the universe
d) actual average density of the universe

a) average density the universe would need for gravity to someday halt the current expansion if dark energy did not exist

What is the primary form of evidence that has led astronomers to conclude that the expansion of the universe is accelerating?
a)observations of the speeds of individual galaxies in clusters
b) measurements of how galaxy speeds away from the Milky Way have increased during the past century
c)observations of white dwarf supernovae
d) measurements of the rotation curve for the universe

c)observations of white dwarf supernovae

Which of the following best sums up current scientific thinking about the nature of dark energy?
a) Dark energy is the source of the mind weapon used by Sith Lords in Star Wars.
b) Dark energy is most likely made up of weakly interacting particles that do not interact with light.
c) Dark energy most likely consists of a form of photons that we can’t see or detect.
d) Dark energy probably exists, but we have little (if any) idea what it is.

d) Dark energy probably exists, but we have little (if any) idea what it is.

According to fossil evidence how far back in time did life on Earth exist?
a)about 2.0 billion years
b) about 545 million years
c) about 65 million years
d) about 3.5 billion years or more

d) about 3.5 billion years or more

Why do scientists say that evolution is a "theory"?
a)because they are not very confident that it really happened
b) because it is supported by only a small amount of evidence
c) because it explains a great deal about life and is supported by an enormous body of evidence
d) because it’s really just a guess about how life developed on Earth

c) because it explains a great deal about life and is supported by an enormous body of evidence

How did oxygen (O2) get into Earth’s atmosphere? a)It was outgassed from volcanoes.
b) It came from chemical reactions with surface rocks.
c) It was released by life through the process of photosynthesis.
d) It was captured from the solar nebula.

c)It was released by life through the process of photosynthesis.

Which of the following is NOT considered crucial for life to exist on some world?
a)a source of nutrients
b) a source of energy that can be used by life
c)an atmosphere
d)liquid water

d)liquid water

Which of the following places is NOT generally considered a potential home for life in our solar system?
a)Jupiter’s atmosphere
b) Mars
c) Europa
d) Titan

a)Jupiter’s atmosphere

Why don’t we expect to find life on planets orbiting high-mass stars?
a)The high-mass stars emit too much ultraviolet radiation.
b)Planets cannot have stable orbits around high-mass stars.
c)The stars are too hot to allow for life.
d) The lifetime of a high-mass star is too short.

d)The lifetime of a high-mass star is too short.

Looking for an Earth-size planet around a nearby star (besides the Sun) is like looking for a pinhead located _________.
a)a few hundred kilometers away
b) thousands of kilometers away
c) across the street
d) across the length of a football field

b) thousands of kilometers away

In the Drake equation (Number of Civilizations ≡ N HP × f life × f civ × f now), what do we mean by f now?
a) the fraction of civilizations in the universe that currently are sending messages to us
b) the fraction of all species ever to exist that we currently are aware of
c) the fraction of planets in the galaxy on which a civilization could theoretically develop right now
d) the fraction of planets with civilizations at the present time (as opposed to only in the past or future)

d) the fraction of planets with civilizations at the present time (as opposed to only in the past or future)

We have sent several spacecraft on trajectories that will ultimately take them into interstellar space (Pioneer 10 and 11, Voyager 1 and 2, New Horizons). How long will it take these spacecraft to travel as far as the nearest stars?
a)a few decades
b) a few hundred years
c) never, because they will rust and fall apart
d) tens of thousands of years
e)about a thousand years

d) tens of thousands of years

Einstein’s theory of relativity tells us that travelers who make a high-speed trip to a distant star and back will _________.
a)will be the same physiological age as people who stay behind on Earth
b)age more than people who stay behind on Earth
c) age less than people who stay behind on Earth
d) never be able to make the trip within their lifetimes

c) age less than people who stay behind on Earth

According to modern science, approximately how old is the Sun?
a) 25 million years
b)10,000 years
c)4.5 billion years
d)400 million years

c)4.5 billion years

Which of the following correctly describes how the process of gravitational contraction can make a star hot?
a)Gravitational contraction involves the generation of heat by chemical reactions, much like the burning of coal.
b)When a star contracts in size, gravitational potential energy is converted to thermal energy.
c) Gravitational contraction involves nuclear fusion, which generates a lot of heat.
D) Heat is generated when gravity contracts, because gravity is an inverse square law force.

b)When a star contracts in size, gravitational potential energy is converted to thermal energy.

What two physical processes balance each other to create the condition known as gravitational equilibrium in stars?
a)the strong force and the electromagnetic force
b) the strong force and the weak force
c) gravitational force and surface tension
d) gravitational force and outward pressure

d) gravitational force and outward pressure

The source of energy that keeps the Sun shining today is _________.
a)nuclear fusion
b) chemical reactions (fire)
c) gravitational contraction
d) nuclear fission

a)nuclear fusion

Energy balance in the Sun refers to a balance between _________.
a-the force of gravity pulling inward and the force due to pressure pushing outward
b- the mass that the Sun loses each second and the amount of mass converted into energy each second
c- the rate at which fusion generates energy in the Sun’s core and the rate at which the Sun’s surface radiates energy into space
d- the amount of energy the Sun radiates into space and the amount of energy that reaches Earth

c- the rate at which fusion generates energy in the Sun’s core and the rate at which the Sun’s surface radiates energy into space

From center outward, which of the following lists the "layers" of the Sun in the correct order?
a)core, convection zone, radiation zone, corona, chromosphere, photosphere
b) core, radiation zone, convection zone, corona, chromosphere, photosphere
c) core, radiation zone, convection zone, photosphere, chromosphere, corona
d) core, corona, radiation zone, convection zone, photosphere, chromosphere

c) core, radiation zone, convection zone, photosphere, chromosphere, corona

What are the appropriate units for the Sun’s luminosity?
a)kilograms
b)newtons
c) watts
d) joules

c) watts

The overall result of the proton-proton chain is that __________.
a)4 H becomes 1 He + energy
b)p + p becomes 2H + energy
c) 6 H becomes 1 He + energy
d) Individual protons are joined into long chains of protons.

a)4 H becomes 1 He + energy

To estimate the central temperature of the Sun, scientists _________.
a)use computer models to predict interior conditions
b) use hot gas to create a small Sun in a laboratory
c) send probes to measure the temperature
d) monitor changes in Earth’s atmosphere

a)use computer models to predict interior conditions

How is the sunspot cycle directly relevant to us here on Earth?
a)The sunspot cycle is the cause of global warming.
b)Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment.
c)The Sun’s magnetic field, which plays a major role in the sunspot cycle, affects compass needles that we use on Earth.
d)The sunspot cycle strongly influences Earth’s weather.
e)The brightening and darkening of the Sun that occurs during the sunspot cycle affects plant photosynthesis here on Earth.

b)Coronal mass ejections and other activity associated with the sunspot cycle can disrupt radio communications and knock out sensitive electronic equipment.

The total amount of power (in watts, for example) that a star radiates into space is called its _________.
a)luminosity
b) apparent brightness
c) absolute magnitude
d) flux

a)luminosity

According to the inverse square law of light, how will the apparent brightness of an object change if its distance to us triples?
a)Its apparent brightness will decrease by a factor of 3.
b) Its apparent brightness will decrease by a factor of 9.
c) Its apparent brightness will increase by a factor of 9.
d)Its apparent brightness will increase by a factor of 3.

b) Its apparent brightness will decrease by a factor of 9.

Assuming that we can measure the apparent brightness of a star, what does the inverse square law for light allow us to do?
a)determine both the star’s distance and luminosity from its apparent brightness
b)calculate the star’s luminosity if we know its distance, or calculate its distance if we know its luminosity
c) calculate the star’s surface temperature if we know either its luminosity or its distance
d)determine the distance to the star from its apparent brightness

b)calculate the star’s luminosity if we know its distance, or calculate its distance if we know its luminosity

If star A is closer to us than star B, then Star A’s parallax angle is _________.
a)larger than that of Star B
b) fewer parsecs than that of Star B
c) hotter than that of Star B
d) smaller than that of Star B

a)larger than that of Star B

From hottest to coolest, the order of the spectral types of stars is _________. a)OMKGFBA
b) OBAGFKM
c) OBAFGKM
d) ABCDEFG
e) ABFGKMO

c) OBAFGKM

Astronomers can measure a star’s mass in only certain cases. Which one of the following cases might allow astronomers to measure a star’s mass?
a)The star is a member of a binary star system.
b) We know the star’s luminosity and distance.
c)The star is of spectral type G.
d)The star is of spectral type A.

a)The star is a member of a binary star system.

The axes on a Hertzsprung-Russell (H-R) diagram represent _________.
a)mass and luminosity
b) luminosity and apparent brightness
c) mass and radius
d) luminosity and surface temperature

d) luminosity and surface temperature

On an H-R diagram, stellar radii _________.
a)are impossible to determine
b)are greatest in the lower left and least in the upper right
c)decrease from left to right
d)increase diagonally from the lower left to the upper right

d)increase diagonally from the lower left to the upper right

How is the lifetime of a star related to its mass?
a)More massive stars live much longer lives than less massive stars.
b)More massive stars live slightly longer lives than less massive stars.
c) More massive stars live slightly shorter lives than less massive stars.
d) More massive stars live much shorter lives than less massive stars.

d) More massive stars live much shorter lives than less massive stars.

What is the common trait of all main sequence stars?
a)They generate energy through hydrogen fusion in their core.
b)They are all spectral type G.
c)They are in the final stage of their lives.
d) They all have approximately the same mass.

a)They generate energy through hydrogen fusion in their core.

What do we mean by the main-sequence turnoff point of a star cluster, and what does it tell us?
a)It is the faintest and coldest main sequence star in a cluster, and it tells us the cluster’s age.
b)It is the point in a star cluster beyond which main sequence stars are not found, and it tells us the cluster’s distance.
c) It is the mass of the most massive star in the star cluster, and it tells us the cluster’s size.
d) It is the spectral type of the hottest main sequence star in a star cluster, and it tells us the cluster’s age.

d)It is the spectral type of the hottest main sequence star in a star cluster, and it tells us the cluster’s age.

The interstellar clouds called molecular clouds are _______.
a)clouds that are made mostly of complex molecules such as carbon dioxide and sulfur dioxide
b)the cool clouds in which stars form
c) the clouds in which elements such as carbon, nitrogen, and oxygen are made
d)the hot clouds of gas expelled by dying stars

b)the cool clouds in which stars form

Which part of the electromagnetic spectrum generally gives us our best views of stars forming in dusty clouds?
a)infrared
b) ultraviolet
c)blue light
d) visible light

a)infrared

Most interstellar clouds remain stable in size because the force of gravity is opposed by _______ within the cloud.
a)stellar winds
b) radiation pressure
c) thermal pressure
d) degeneracy pressure

c) thermal pressure

What kind of gas cloud is most likely to give birth to stars?
a)a hot, low-density gas cloud
b) a hot, dense gas cloud
c) a cold, dense gas cloud
d)a cold, low-density gas cloud

c) a cold, dense gas cloud

Which of the following statements is probably true about the very first stars in the universe?
a)They were made only from hydrogen and helium.
b)They were made approximately of 98 percent hydrogen and helium, and 2 percent of heavier elements.
c) They were probably orbited only by terrestrial planets, but no jovian planets.
d)They were made from pure energy.

a)They were made only from hydrogen and helium.

What law explains why a collapsing cloud usually forms a protostellar disk around a protostar?
a)Kepler’s third law
b) conservation of angular momentum
c)the universal law of gravitation
d) Wien’s law

b) conservation of angular momentum

What can we learn about a star from a life track on an H-R diagram?
a)The surface temperature and luminosity the star will have at each stage of its life.
b)the star’s current stage of life
c)the star’s age
d) how the star’s distance from Earth varies at different times in its life

a)The surface temperature and luminosity the star will have at each stage of its life.

Which star spends the longest time in the protostellar phase of life?
a)a 3 solar mass star
b) a 1 solar mass star
c) a 5 solar mass star
d) a 2 solar mass star
e)a 4 solar mass star

b) a 1 solar mass star

What is the approximate range of masses that newborn main sequence stars can have?
a)0.001 to 150 solar masses
b) 0.001 to 10 solar masses
c) 0.1 to 1,000 solar masses
d)0.1 to 150 solar masses
e) 0.1 to 10 solar masses

d)0.1 to 150 solar masses

Which of the following statements about brown dwarfs is NOT true?
a)Brown dwarfs eventually collapse to become white dwarfs.
b) All brown dwarfs have masses less than about 8 percent that of our Sun.
C) Brown dwarfs form like ordinary stars but are too small to sustain nuclear fusion in their cores.
D)Brown dwarfs are supported against gravity by degeneracy pressure, which does not depend on the object’s temperature.

a)Brown dwarfs eventually collapse to become white dwarfs.

Which of the following stars will live longest?
a)4 solar mass star
b)1 solar mass star
c)3 solar mass star
d) 2 solar mass star

b)1 solar mass star

Which of the following lists the stages of life for a low-mass star in the correct order?
a)protostar, main-sequence star, red giant, supernova, neutron star
b) protostar, main-sequence star, red giant, planetary nebula, white dwarf
c) main-sequence star, white dwarf, red giant, planetary nebula, protostar
d) protostar, main-sequence star, planetary nebula, red giant

b) protostar, main-sequence star, red giant, planetary nebula, white dwarf

What happens when a main-sequence star exhausts its core hydrogen fuel supply?
a)The core shrinks while the rest of the star expands.
b) The core immediately begins to fuse its helium into carbon.
c)The entire star shrinks in size.
d)The star becomes a neutron star.

a)The core shrinks while the rest of the star expands.

The main source of energy for a star as it grows in size to become a red giant is ______.
a)hydrogen fusion in the central core
b)hydrogen fusion in a shell surrounding the central core
c)gravitational contraction
d)helium fusion in the central core

b)hydrogen fusion in a shell surrounding the central core

An H-R diagram for a globular cluster will show a horizontal branch—a line of stars above the main sequence but to the left of the subgiants and red giants. Which of the following statements about these horizontal branch stars is true?
a)In a particular star cluster, all horizontal branch stars have the same spectral type.
b) They have inert (nonburning) carbon cores.
c) Their sole source of energy is hydrogen shell burning.
d) They generate energy through both hydrogen fusion and helium fusion.

d) They generate energy through both hydrogen fusion and helium fusion.

The ultimate fate of our Sun is to _____.
a)become a rapidly spinning neutron star
b)become a white dwarf that will slowly cool with time
c) become a black hole
d) explode in a supernova

b)become a white dwarf that will slowly cool with time

Which low-mass star does NOT have fusion occurring in its central core?
a) a helium burning star (a horizontal branch star)
b) a main-sequence star
c) a red giant

c) a red giant

Which of the following pairs of atomic nuclei would feel the strongest repulsive electromagnetic force if you tried to push them together?
a)hydrogen and helium
b) helium and helium
c) hydrogen and deuterium
d) hydrogen and hydrogen

b) helium and helium

Which of the following stars will certainly end its life in a supernova?
a)the Sun
b) a 10 solar mass star
c) a red giant star
d) a neutron star

b) a 10 solar mass star

In order to predict whether a star will eventually fuse oxygen into a heavier element, what do you need to know about the star?
a) its luminosity
b) how much oxygen it now has in its core
c)its mass
d) its overall abundance of elements heavier than helium

c)its mass

Why is iron significant to understanding how a supernova occurs?
a) Iron is the heaviest of all atomic nuclei, and thus no heavier elements can be made.
b) Supernovae often leave behind neutron stars, which are made mostly of iron.
c)The fusion of iron into uranium is the reaction that drives a supernova explosion.
d) Iron cannot release energy either by fission or fusion.

d) Iron cannot release energy either by fission or fusion.

Algol consists of a 3.7 M Sun main-sequence star and a 0.8 M Sun subgiant. Why does this seem surprising, at least at first?a)It doesn’t make sensea to find a subgiant in a binary star system.
b) The two stars in a binary system should both be at the same stage of life; that is, they should either both be main sequence stars or both be subgiants.
c) A star with a mass of 3.7 M Sun is too big to be a main-sequence star.
D) The two stars should be the same age, so we’d expect the subgiant to be more massive than the main-sequence star.

D) The two stars should be the same age, so we’d expect the subgiant to be more massive than the main-sequence star.

Where does gold (the element) come from?
a)It is produced by mass transfer in close binaries.
b) It is produced during the supernova explosions of high-mass stars.
c) It is produced during the late stages of fusion in low-mass stars.
d) It was produced during the Big Bang.

b) It is produced during the supernova explosions of high-mass stars.

A typical white dwarf is _________.
a)about the same size and mass as the Sun but much hotter
b)as large in diameter as the Sun but only about as massive as Earth
c)as massive as the Sun but only about as large in size as Earth
d) as massive as the Sun but only about as large in size as Jupiter

c)as massive as the Sun but only about as large in size as Earth

The maximum mass of a white dwarf is _________.
a)limitless; there is no theoretical limit to the maximum mass of a white dwarf
b) about 1.4 times the mass of our Sun
c) about 3 times the mass of our Sun
d)about the mass of our Sun

b) about 1.4 times the mass of our Sun

According to our modern understanding, what is a nova?
a) the sudden formation of a new star in the sky
b) a rapidly spinning neutron star
c) an explosion on the surface of a white dwarf in a close binary system
d) the explosion of a massive star at the end of its life

c) an explosion on the surface of a white dwarf in a close binary system

Suppose that a white dwarf is gaining mass through accretion in a binary system. What happens if the mass someday reaches the 1.4 solar mass limit?

a) The white dwarf will collapse to become a black hole.
b) The white dwarf will collapse in size, becoming a neutron star.
c) The white dwarf will undergo a nova explosion.
d) The white dwarf will explode completely as a white dwarf supernova.

d) The white dwarf will explode completely as a white dwarf supernova.

A typical neutron star is more massive than our Sun and about the size (radius) of _________.

a) a small asteroid (10 km in diameter)
b) Jupiter
c)the Moon
d)Earth

a) a small asteroid (10 km in diameter)

Pulsars are thought to be _________.

a)rapidly rotating neutron stars
b) accreting black holes
c)accreting white dwarfs
d)unstable high-mass stars

a)rapidly rotating neutron stars

How is an X-ray burst (in an X-ray binary system) similar to a nova?

a) Both result in the complete destruction of their host stars.
b) Both involve explosions on the surface of a stellar corpse.
c)dBoth are thought to involve fusion of hydrogen into helium.
d) Both typically recur every few hours to every few days.

b) Both involve explosions on the surface of a stellar corpse.

What do we mean by the event horizon of a black hole?

a)It is the place where X rays are emitted from black holes.
b) It is the very center of the black hole.
c) It is the distance from the black hole at which stable orbits are possible.
d) It is the point beyond which neither light nor anything else can escape.

d) It is the point beyond which neither light nor anything else can escape.

Imagine that our Sun were magically and suddenly replaced by a black hole of the same mass (1 solar mass). What would happen to Earth in its orbit?

a) Earth would slowly spiral inward until it settled into an orbit about the size of Mercury’s current orbit.
b)Earth would orbit faster, but at the same distance.
c)Earth would almost instantly be sucked into oblivion in the black hole.
d)Nothing—Earth’s orbit would remain the same.

d)Nothing—Earth’s orbit would remain the same.

What makes us think that the star system Cygnus X-1 contains a black hole?

a) It emits X-rays characteristic of an accretion disk, but the unseen star in the system is too massive to be a neutron star.
b)c The fact that we see strong X-ray emission tells us that the system must contain a black hole.
c)d No light is emitted from this star system, so it must contain a black hole.
d) Cygnus X-1 is a powerful X-ray burster, so it must contain a black hole.

a) It emits X-rays characteristic of an accretion disk, but the unseen star in the system is too massive to be a neutron star.

The Schwarzschild radius of a black hole depends on ________.

a) only the mass of the black hole
b) both the mass and chemical composition of the black hole
c)d the observationally measured radius of the black hole
d) the way in which the black hole formeda

a) only the mass of the black hole

Based on current evidence, which of the following statements about gamma ray bursts is true?

a)b They occur in the same types of close binary systems that produce X-ray bursts.
b) All gamma ray bursts are produced by supernovae.
c)d They come primarily from the Milky Way’s central black hole.
d) All those that we have detected occurred in distant galaxies.

d) All those that we have detected occurred in distant galaxies.

Which of the following statements about electron degeneracy pressure and neutron degeneracy pressure is true?

a) Both electron degeneracy pressure and neutron degeneracy pressure help govern the internal structure of a main-sequence star.
b) Electron degeneracy pressure is the main source of pressure in white dwarfs, while neutron degeneracy pressure is the main source of pressure in neutron stars.
c) The life of a white dwarf is an ongoing battle between electron degeneracy pressure and neutron degeneracy pressure.
d) In a black hole, the pressure coming from neutron degeneracy pressure is slightly greater than that coming from electron degeneracy pressure.a

b) Electron degeneracy pressure is the main source of pressure in white dwarfs, while neutron degeneracy pressure is the main source of pressure in neutron stars.

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