question

Which of the following has your "cosmic address" in the correct order?

answer

You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe

question

Using the ideas discussed in your textbook, in what sense are we "star stuff"?

answer

Nearly every atom from which we are made was once inside of a star.

question

How are galaxies important to our existence?

answer

Galaxies recycle material from one generation of stars to the next, and without this recycling we could not exist.

question

When we look at an object that is 1,000 light-years away we see it _________.

answer

as it was 1,000 years ago

question

Suppose we look at two distant galaxies: Galaxy 1 is twice as far away as Galaxy 2. In that case _________.

answer

we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy 2

question

Suppose we make a scale model of our solar system, with the Sun the size of a grapefruit. Which of the following best describes what the planets would look like?

answer

The planets are all much smaller than the Sun. Four planets are within about 20 meters of the Sun, while the rest planets are spread much farther apart.

question

If you could count stars at a rate of about one per second, how long would it take to count all the stars in the Milky Way Galaxy?

answer

Several thousand years

question

The total number of stars in the observable universe is about _________.

answer

the same as the number of grains of sand on all the beaches on Earth

question

Where is our solar system located within the Milky Way Galaxy?

answer

Roughly halfway between the center and the edge of the visible disk of the galaxy

question

If we imagine the history of the universe compressed into one year, dinosaurs became extinct _________.

answer

yesterday morning

question

Relative to the age of the universe, how old is our solar system?

answer

It is about one-third the age of the universe.

question

How do the speeds at which we are moving with Earth's rotation and orbit compare to the speeds of more familiar objects?

answer

Earth's rotation carries most people around the axis faster than a commercial jet travels, and Earth's orbit carries us around the Sun faster than the Space Shuttle orbits Earth.

question

Why do the patterns of the stars in our sky look the same from year to year?

answer

Because the stars in the constellations are so far away.

question

Astronomers infer that the universe is expanding because distant galaxies all appear to _________.

answer

be moving away from us, with more distant ones moving faster

question

Which statement about motion in the universe is not true?

answer

The mysterious dark matter is the fastest-moving material in the universe.

question

Which of the following is not a general difference between a planet and a star?

answer

All planets are made of rock and all stars are made of gas.

question

Our solar system consists of _________.

answer

the Sun and all the objects that orbit it

question

A typical galaxy is a _________.

answer

collection of a few hundred million to a trillion or more stars, bound together by gravity

question

Which of the following best describes what we mean by the universe?

answer

The sum total of all matter and energy

question

What do astronomers mean by the Big Bang?

answer

The event that marked the beginning of the expansion of the universe

question

What do we mean when we say that the universe is expanding?

answer

Average distances between galaxies are increasing with time.

question

Based on observations of the universal expansion, the age of the universe is about _________.

answer

14 billion years

question

A television advertisement claiming that a product is light-years ahead of its time does not make sense because _________.

answer

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

question

The term observable universe refers to _________.

answer

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

question

On a scale in which the distance from Earth to the Sun is about 15 meters, the distance from Earth to the Moon is _________.

answer

small enough to fit within your hand

question

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?

answer

About the distance across the United States

question

The number of stars in the Milky Way Galaxy is approximately _________.

answer

a few hundred billion

question

An astronomical unit (AU) is _________.

answer

the average distance between Earth and the Sun

question

What is the ecliptic plane?

answer

The plane of Earth's orbit around the Sun

question

How long does it take the Earth to complete one orbit around the Sun?

answer

One year

question

Which of the following statements about the celestial sphere is NOT true?

answer

The "celestial sphere" is another name for our universe.

question

The Andromeda Galaxy is faintly visible to the naked eye in the constellation Andromeda. Suppose instead it were located in the same direction in space as the center of the Milky Way Galaxy (but still at its current distance). How would it appear to the eye in that case?

answer

We could not see it at all.

question

An angle of 1 arcsecond is _________.

answer

less than the thickness of a human hair held at arm's length

question

When traveling north from the United States into Canada, you'll see the North Star (Polaris) getting _________.

answer

higher in the sky

question

Suppose you use the Southern Cross to determine that the south celestial pole appears 40 degrees above your horizon. Then you must be located at _________.

answer

latitude 40 degrees south

question

Suppose you are facing north and you see the Big Dipper close to your northern horizon, with Polaris (and the Little Dipper) above it. Where will you see the Big Dipper in six hours?

answer

To the right of Polaris; that is, 90 degrees counterclockwise from its current position

question

In any particular place on Earth, certain constellations are visible in the evening only at certain times of the year because _________.

answer

our evening view of space depends on where Earth is located in its orbit around the Sun

question

The Sun's path, as viewed from the equator, is highest in the sky on _________.

answer

the spring and fall equinoxes

question

Suppose Earth's axis tilt was significantly greater than its current 23.5 degrees, but Earth's rotation period and orbital period were unchanged. Which statement below would not be true?

answer

The length of each season (for example, the number of days from the summer solstice to the fall equinox) would be significantly longer than it is now.

question

If our year were twice as long (that is, if Earth took twice as many days to complete each orbit around the Sun), but Earth's rotation period and axis tilt were unchanged, then _________.

answer

the four seasons would each be twice as long as they are now

question

How does Earth's varying distance from the Sun affect our seasons?

answer

It doesn't — Earth's orbital distance plays no significant role in the seasons.

question

Suppose you live in the United States and you see a crescent moon in your evening sky tonight. What will a friend in South America see tonight?

answer

Your friend will also see a crescent moon.

question

Suppose it is full moon. What phase of Earth would someone on the Moon see at this time?

answer

new Earth

question

It's 6 am and the Moon is at its highest point in your sky (crossing the meridian). What is the Moon's phase?

answer

third quarter

question

You observe a full moon rising at sunset. What will you see at midnight?

answer

A full moon high in the sky

question

All the following statements are true. Which one explains the reason that there is not a solar eclipse at every new moon?

answer

The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane.

question

For most of history, the lack of observable stellar parallax was interpreted to mean that _________.

answer

Earth is stationary at the center of the universe

question

During the period each year when we see Mars undergoing apparent retrograde motion in our sky, what is really going on in space?

answer

Earth is catching up with and passing by Mars in their respective orbits.

question

Suppose you see a photo showing Jupiter half in sunlight and half in shadow (that is, a first quarter Jupiter). This photo might have been taken by _________.

answer

the Galileo spacecraft that orbited Jupiter in the 1990s

question

About how many stars are visible to the naked eye on a clear, dark night away from city lights?

answer

A couple thousand

question

What do astronomers mean by a constellation?

answer

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

question

What is the ecliptic?

answer

The path the Sun appears to trace around the celestial sphere each year

question

What is the celestial sphere?

answer

The celestial sphere is a representation of how the entire sky looks as seen from Earth.

question

What do we mean when we talk about the Milky Way in our sky?

answer

The patchy band of light that outlines the plane of the Milky Way Galaxy as seen from Earth.

question

Which of the following statements does not use the term angular size or angular distance correctly?

answer

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

question

Which of the following correctly describes the meridian in your local sky?

answer

A half-circle extending from your horizon due north, through your zenith, to your horizon due south

question

The point directly over your head is called _________.

answer

the zenith

question

Stars that are visible in the local sky on any clear night of the year, at any time of the night, are called _________.

answer

circumpolar

question

We describe a location on Earth's surface by stating its _________.

answer

latitude and longitude

question

If you are located in the Northern Hemisphere, which of the following correctly describes a relationship between the sky and your location?

answer

The altitude of the north celestial pole equals your latitude.

question

Which of the following best describes why we have seasons on Earth?

answer

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

question

Each choice below describes how a few astronomical phenomena are related to time periods. Which list is entirely correct? (Careful: some lists are partially correct.)

answer

Earth's rotation defines a day. The cycle of the Moon's phases takes about a month. Earth's orbit defines a year. Earth's cycle of axis precession takes 26,000 years.

question

If we have a new moon today, when we will have the next full moon?

answer

In about 2 weeks

question

We cannot see a new moon in our sky because _________.

answer

a new moon is quite near the Sun in the sky

question

Lunar eclipses can occur only during a _________.

answer

full moon

question

What is the saros cycle?

answer

The roughly 18-year cycle over which the pattern of eclipses repeats

question

During the time that a planet is in its period of apparent retrograde motion: _________

answer

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

question

What is stellar parallax?

answer

It is the slight back-and-forth shifting of star positions that occurs as we view the stars from different positions in Earth's orbit of the Sun.

question

Suppose the planet Uranus were much brighter in the sky, so that it was as easily visible to the naked eye as Jupiter or Saturn. Which one of the following statements would most likely be true in that case?

answer

A week would have eight days instead of seven.

question

How does a 12-month lunar calendar differ from our 12-month solar calendar?

answer

It has about 11 fewer days.

question

Which of the following best describes a set of conditions under which archaeoastronomers would conclude that an ancient structure was used for astronomical purposes?

answer

The structure has holes in the ceiling that allow viewing the passage of constellations that figure prominently in the culture's folklore, and many other structures built by the same culture have ceiling holes placed in the same way.

question

How did the Ptolemaic model explain the apparent retrograde motion of the planets?

answer

The planets moved along small circles that moved on larger circles around the Earth.

question

When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not?

answer

Copernicus used perfect circles for the orbits of the planets.

question

Earth is farthest from the Sun in July and closest to the Sun in January. During which Northern Hemisphere season is Earth moving fastest in its orbit?

answer

Winter

question

According to Kepler's third law (p^2 = a^3), how does a planet's mass affect its orbit around the Sun?

answer

A planet's mass has no effect on its orbit around the Sun.

question

All the following statements are true. Which one follows directly from Kepler's third law (p^2 = a^3)?

answer

Venus orbits the Sun at a slower average speed than Mercury.

question

Suppose a comet orbits the Sun on a highly eccentric orbit with an average (semimajor axis) distance of 1 AU. How long does it take to complete each orbit, and how do we know?

answer

1 year, which we know from Kepler's third law.

question

Galileo challenged the idea that objects in the heavens were perfect by _________.

answer

observing sunspots on the Sun and mountains on the Moon

question

Galileo observed all of the following. Which observation offered direct proof of a planet orbiting the Sun?

answer

Phases of Venus

question

Which of the following is not consistent with the major hallmarks of science?

answer

Science consists of proven theories that are understood to be true explanations of reality.

question

Which of the following is not part of a good scientific theory?

answer

A scientific theory cannot be accepted until it has been proven true beyond all doubt.

question

Only one of the statements below uses the term theory in its correct, scientific sense. Which one?

answer

Einstein's theory of relativity has been tested and verified thousands of times.

question

Imagine for a moment that despite all the evidence, Earth actually is not rotating and orbiting the Sun. Which of these hypothetical observations (none of them are real) would be inconsistent with our Sun-centered view of the solar system?

answer

We discover a small planet beyond Saturn that rises in the west and sets in the east each day.

question

What practical value did astronomy offer to ancient civilizations?

answer

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

question

Scientific thinking is _________.

answer

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

question

The names of the seven days of the week are based on _________.

answer

the seven naked-eye objects that appear to move among the constellations

question

The Metonic cycle is

answer

used to keep lunar calendars approximately synchronized with solar calendars.

question

Ptolemy was important in the history of astronomy because he _________.

answer

developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries

question

The ancient Greeks get a lot of attention for their contributions to science because _________.

answer

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

question

What do we mean by a geocentric model of the universe?

answer

A model designed to explain what we see in the sky while having the Earth located in the center of the universe.

question

What was the Ptolemaic model?

answer

An Earth-centered model of planetary motion published by Ptolemy

question

The great contribution of Nicholas Copernicus was to _________.

answer

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

question

The great contribution of Tycho Brahe was to _________.

answer

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

question

Which of the following was not observed by Galileo?

answer

Stellar parallax. He DID observe: four moons orbiting Jupiter, Phases of Venus, and mountains and valleys on the moon.

question

Which of the following statements about an ellipse is not true?

answer

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

question

Which of the following is not one of, nor a direct consequence of, Kepler's Laws?

answer

The force of attraction between any two objects decreases with the square of the distance between their centers.

question

Scientific models are used to _________.

answer

make specific predictions that can be tested through observations or experiments

question

In science, a broad idea that has been repeatedly verified so as to give scientists great confidence that it represents reality is called _________.

answer

a theory

question

Which of the following represents a case in which you are not accelerating?

answer

Driving in a straight line at 60 miles per hour

question

Suppose you drop a 10-pound weight and a 5-pound weight on the Moon, both from the same height at the same time. What will happen?

answer

Both will hit the ground at the same time.

question

Why are astronauts weightless in the Space Station?

answer

Because the Space Station is constantly in free-fall around the Earth

question

A net force acting on an object will always cause a change in the object's _________.

answer

momentum

question

Suppose you are in an elevator that is traveling upward at constant speed. How does your weight compare to your normal weight on the ground?

answer

It is the same.

question

The planets never travel in a straight line as they orbit the Sun. According to Newton's second law of motion, this must mean that _________.

answer

a force is acting on the planets

question

Suppose the Sun were suddenly to shrink in size but that its mass remained the same. According to the law of conservation of angular momentum, what would happen?

answer

The Sun would rotate faster than it does now.

question

Suppose you kick a soccer ball straight up to a height of 10 meters. Which of the following is true about the gravitational potential energy of the ball during its flight?

answer

The ball's gravitational potential energy is greatest at the instant when the ball is at its highest point.

question

Suppose you heat an oven to 400°F and boil a pot of water. Which of the following explains why you would be burned by sticking your hand briefly in the pot but not by sticking your hand briefly in the oven?

answer

The water can transfer heat to your arm more quickly than the air.

question

Which of the following scenarios involves energy that we would typically calculate with Einstein's formula E=mc 2?

answer

A small amount of the hydrogen in of a nuclear bomb becomes energy as fusion converts the hydrogen to helium.

question

A rock held above the ground has potential energy. As the rock falls, this potential energy is converted to kinetic energy. Finally, the rock hits the ground and stays there. What has happened to the energy?

answer

The energy goes to producing sound and to heating the ground, rock, and surrounding air.

question

Suppose that the Sun shrank in size but that its mass remained the same. What would happen to the orbit of the Earth?

answer

Earth's orbit would be unaffected.

question

Imagine another solar system, with a star of the same mass as the Sun. Suppose a planet with a mass twice that of Earth (2M Earth) orbits at a distance of 1 AU from the star. What is the orbital period of this planet?

answer

1 year.

question

Imagine another solar system, with a star more massive than the Sun. Suppose a planet with the same mass as Earth orbits at a distance of 1 AU from the star. How would the planet's year (orbital period) compare to Earth's year?

answer

The planet's year would be shorter than Earth's.

question

Newton showed that Kepler's laws are _________.

answer

natural consequences of the law of universal gravitation

question

Each of the following lists two facts. Which pair of facts can be used with Newton's version of Kepler's third law to determine the mass of the Sun?

answer

Earth is 150 million km from the Sun and orbits the Sun in one year.

question

When space probe Voyager 2 passed by Saturn, its speed increased (but not due to firing its engines). What must have happened?

answer

Saturn must have lost a very tiny bit of its orbital energy.

question

Suppose that a lone asteroid happens to be passing Jupiter on an unbound orbit (well above Jupiter's atmosphere and far from all of Jupiter's moons.) Which of the following statements would be true?

answer

The asteroid's orbit around Jupiter would not change, and it would go out on the same unbound orbit that it came in on.

question

Which of the following best describes the origin of ocean tides on Earth?

answer

Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the Earth.

question

At which lunar phase(s) are tides most pronounced (for example, the highest high tides)?

answer

Both new and full moons

question

Which of the following best explains why the Moon's orbital period and rotation period are the same?

answer

The Moon once rotated faster, but tidal friction slowed the rotation period until it matched the orbital period.

question

The difference between speed and velocity is that _________.

answer

velocity also includes a direction

question

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?

answer

30 m/s

question

Momentum is defined as _________.

answer

mass times velocity

question

Suppose you lived on the Moon. Which of the following would be true?

answer

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

question

In which of the following cases would you feel weightless?

answer

While falling from a roof

question

Which of the following statements is not one of Newton's Laws of Motion?

answer

What goes up must come down.

question

Newton's Second Law of Motion tells us that the net force applied to an object equals its _________.

answer

mass times acceleration

question

Suppose that two objects collide. Which of the following things is not the same both before and after the collision?

answer

The total temperature of the objects

question

When a spinning ice skater pulls in his arms, he spins faster because _________.

answer

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

question

The energy attributed to an object by virtue of its motion is known as _________.

answer

kinetic energy

question

Radiative energy is _________.

answer

energy carried by light

question

Absolute zero is _________.

answer

0 Kelvin

question

What does temperature measure?

answer

The average kinetic energy of particles in a substance

question

In the formula E=mc^2, what does E represent?

answer

The mass-energy, or potential energy stored in an object's mass

question

According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them _________.

answer

decreases by a factor of 9

question

What is the difference between a bound orbit and an unbound orbit around the Sun?

answer

An object on a bound orbit follows the same path around the Sun over and over, while an object on an unbound orbit approaches the Sun just once and then never returns.

question

Why is Newton's version of Kepler's third law so useful to astronomers?

answer

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

question

What do we mean by the orbital energy of an orbiting object (such as a planet, moon, or satellite)?

answer

Orbital energy is the sum of the object's kinetic energy and its gravitational potential energy as it moves through its orbit.

question

Which statement must be true in order for a rocket to travel from Earth to another planet?

answer

It must attain escape velocity from Earth.

question

Approximately where is it currently high tide on Earth?

answer

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

question

Which of the following best describes why we say that light is an electromagnetic wave?

answer

The passage of a light wave can cause electrically charged particles to move up and down.

question

Which of the following statements about X rays and radio waves is not true?

answer

X rays travel through space faster than radio waves.

question

Suppose you built a scale-model atom in which the nucleus is the size of a tennis ball. About how far would the cloud of electrons extend?

answer

Several kilometers

question

Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms different isotopes of the same element?

answer

Atom 1: nucleus with 7 protons and 8 neutrons, surrounded by 7 electrons; Atom 2: nucleus with 7 protons and 7 neutrons, surrounded by 7 electrons

question

Which of the following statements is true of green grass?

answer

It absorbs red light and reflects green light.

question

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space?

answer

The cloud is cool and lies between you and a hot star.

question

Which of the following statements about thermal radiation is always true?

answer

A hot object emits more radiation per unit surface area than a cool object.

question

Betelgeuse is the bright red star representing the left shoulder of the constellation Orion. All the following statements about Betelgeuse are true. Which one can you infer from its red color?

answer

Its surface is cooler than the surface of the Sun.

question

Laboratory measurements show hydrogen produces a spectral line at a wavelength of 486.1 nanometers (nm). A particular star's spectrum shows the same hydrogen line at a wavelength of 486.0 nm. What can we conclude?

answer

The star is moving toward us.

question

Suppose that Star X and Star Y both have redshifts, but Star X has a larger redshift than Star Y. What can you conclude?

answer

Star X is moving away from us faster than Star Y.

question

Studying a spectrum from a star can tell us a lot. All of the following statements are true except one. Which statement is not true?

answer

The total amount of light in the spectrum tells us the star's radius.

question

The angular separation of two stars is 0.1 arcseconds and you photograph them with a telescope that has an angular resolution of 1 arcsecond. What will you see?

answer

The photo will seem to show only one star rather than two.

question

How does the light-collecting area of an 8-meter telescope compare to that of a 2-meter telescope?

answer

The 8-meter telescope has 16 times the light-collecting area of the 2-meter telescope.

question

Which of the following is not an advantage of the Hubble Space Telescope over ground-based telescopes?

answer

It is closer to the stars.

question

The Chandra X-ray Observatory must operate in space because:

answer

X rays do not penetrate Earth's atmosphere.

question

Which of the following is always true about images captured with X-ray telescopes?

answer

They are always shown with colors that are not the true colors of the objects that were photographed.

question

From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?

answer

gamma rays, X rays, ultraviolet, visible light, infrared, radio

question

Which forms of light are lower in energy and frequency than the light that our eyes can see?

answer

infrared and radio

question

When considering light as made up of individual "pieces," each characterized by a particular amount of energy, the pieces are called _________.

answer

photons

question

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?

answer

They have a frequency of 2 hertz.

question

Suppose you know the frequency of a photon and the speed of light. What else can you determine about the photon?

answer

its wavelength and energy

question

Which of the following best describes the fundamental difference between two different chemical elements (such as oxygen and carbon)?

answer

They have different numbers of protons in their nucleus.

question

Consider an atom of carbon in which the nucleus contains 6 protons and 7 neutrons. What is its atomic number and atomic mass number?

answer

atomic number = 6; atomic mass number = 13

question

If we say that a material is opaque to ultraviolet light, we mean that it _________.

answer

absorbs ultraviolet light

question

Visible light from a distant star can be spread into a spectrum by using a glass prism or ______.

answer

a diffraction grating

question

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?

answer

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.

question

An atom that has fewer electrons than protons is called a/an _________.

answer

ion

question

Thermal radiation is defined as _________.

answer

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

question

According to the laws of thermal radiation, hotter objects emit photons with _________.

answer

a shorter average wavelength

question

Suppose you want to know the chemical composition of a distant star. Which piece of information is most useful to you?

answer

the wavelengths of spectral lines in the star's spectrum

question

The spectra of most galaxies show redshifts. This means that their spectral lines _________.

answer

have wavelengths that are longer than normal

question

What is the angular resolution of the human eye?

answer

about 1 arcminute, or 1/60 of a degree

question

Which of the following statements best describes the two principle advantages of telescopes over eyes?

answer

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

question

What do astronomers mean by light pollution?

answer

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

question

The stars in our sky twinkle in brightness and color because of _________.

answer

turbulence in the Earth's atmosphere

question

What is the purpose of adaptive optics?

answer

It reduces blurring caused by atmospheric turbulence for telescopes on the ground.

question

What is the purpose of interferometry?

answer

It allows two or more small telescopes to achieve the angular resolution of a much larger telescope.

Astronomy Ch. 1-5 – Flashcards

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