The maximum efficiency of the best commercial (as opposed to research) solar cells is about

The maximum efficiency of the best commercial (as opposed to research) solar cells is about 

A) 1%
B) 10%
C) 20%
D) essentially 100%

Answer: C

In calculating the amount of solar power an array will collect, the incidence angle of the Sun

In calculating the amount of solar power an array will collect, the incidence angle of the Sun 

A) can be neglected
B) plays a small role, but daily cloudiness dominates
C) has a big effect just as it does in producing the seasons
D) is outweighed by the change in the distance of the Sun due to its elliptical orbit

Answer: C

On the Earth's equator, at an equinox, the Sun rises due east and then

On the Earth's equator, at an equinox, the Sun rises due east and then 

A) passes south of the zenith at noon
B) goes through the zenith at noon
C) passes north of the zenith at noon
D) sets south of west

Answer: B

At the Earth's surface, the average amount of solar power available over 1 square meter is about

At the Earth's surface, the average amount of solar power available over 1 square meter is about 

A) 1 watt
B) 100 watts
C) 1000 watts
D) 10,000 watts

Answer: C

What's the fundamental reason that Mars, unlike the Earth, has become virtually geologically dead?

What's the fundamental reason that Mars, unlike the Earth, has become virtually geologically dead?

A) its large size compared to the Earth
B) its rapid rotation compared to the Earth
C) its small size compared to Earth
D) its farther distance than Earth to the Sun
E) its closer distance than Earth to the Sun

Answer: C

All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space?

All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space?

A) Mars probably once had a much higher density of greenhouse gases in its atmosphere than it does today.
B) Mars lost any global magnetic field that it may once have had.
C) The axis tilt of Mars is thought to change significantly with time.
D) Outgassed water molecules are split apart, and the oxygen then reacts chemically with surface rock on Mars.

Answer: B

What makes us think that Mars must once have had an atmosphere that was warmer and had higher surface pressure?

What makes us think that Mars must once have had an atmosphere that was warmer and had higher surface pressure?

A) The fact that parts of Mars have a lot of craters tell us that Mars must once have been much warmer.
B) We think it for purely theoretical reasons, based on calculations showing that the Sun has brightened with time.
C) The atmosphere is too cold and thin for liquid water today, yet we see evidence that water flowed on the surface in the past.
D) The presence of inactive volcanoes on Mars tells us that there must once have been a lot of outgassing, and hence a thicker atmosphere.

Answer: C

Which of the following best describes the geological histories of the Moon and Mercury?

Which of the following best describes the geological histories of the Moon and Mercury? 

A) All four geological processes were important in their early histories, but only impact cratering still reshapes their surfaces today.
B) Impact cratering is the only major geological process that has affected their surfaces.
C) Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all.
D) Impact cratering shaped these worlds early in their histories. Then, during the past few million years, they were reshaped by episodes of volcanism and tectonics.

Answer: C

What are the two geological features that appear to set Earth apart from all the other terrestrial worlds?

What are the two geological features that appear to set Earth apart from all the other terrestrial worlds?

A) mantle convection and a thick atmosphere
B) plate tectonics and widespread erosion
C) significant volcanism and tectonics
D) a dense core and plate tectonics

Answer: B

The reason that small planets tend to lose interior heat faster than larger planets is essentially the same as the reason that ________.

The reason that small planets tend to lose interior heat faster than larger planets is essentially the same as the reason that ________.

A) thunderstorms tend to form on hot summer days
B) Earth contains more metal than the Moon
C) gas bubbles form and rise upward in boiling water
D) a large baked potato takes longer to cool than a small baked potato

Answer: D

Which internal heat source still generates heat within the terrestrial worlds today?

Which internal heat source still generates heat within the terrestrial worlds today?

A) Heat from convection
B) Heat from differentiation
C) Heat of accretion
D) Heat from radioactive decay

Answer: D

According to current understanding, which of the following is required in order for a planet to have rings?

According to current understanding, which of the following is required in order for a planet to have rings?

A) The planet must once have had a large moon that came too close to it, shattering the moon and creating the ring particles.
B) The planet must be at least as massive as Saturn.
C) The planet must orbit its star at a distance greater than Mars orbits the Sun.
D) The planet must have many small moons that orbit relatively close to the planet in its equatorial plane.

Answer: D

Which of the following is not a piece of evidence supporting the idea that Europa may have a subsurface ocean?

Which of the following is not a piece of evidence supporting the idea that Europa may have a subsurface ocean?

A) Europa has a magnetic field that appears to respond to Jupiter's magnetic field.
B) Photos of Europa's surface show regions that appear to consist of jumbled icebergs frozen in place.
C) Astronomers have detected small lakes of liquid water on Europa's surface.
D) Europa's surface shows very few impact craters.

Answer: C

All the following statements are true. Which one is most important in explaining the tremendous tidal heating that occurs on Io?

All the following statements are true. Which one is most important in explaining the tremendous tidal heating that occurs on Io?

A) Io exhibits synchronous rotation, meaning that its rotation period and orbital period are the same.
B) Io is the closest to Jupiter of Jupiter's large moons.
C) Io orbits Jupiter on an elliptical orbit, due to orbital resonances with other satellites.
D) Io orbits Jupiter in the Io torus, and therefore has a surface that is bombarded by many charged particles.

Answer: C

Which of the following best explains why many jovian moons have been more geologically active than the Moon or Mercury?

Which of the following best explains why many jovian moons have been more geologically active than the Moon or Mercury?

A) Jovian moons are made mostly of ice that can melt or deform at lower temperatures than can the rock and metal that make up the Moon and Mercury.
B) Because of their greater distances from the Sun, the jovian moons receive much less heat from the Sun.
C) The jovian moons probably have far more internal heat generated by radioactive decay than do the Moon or Mercury.
D) The jovian moons are considerably larger than the Moon and Mercury and therefore have retained much more internal heat.

Answer: A

What would happen to Jupiter if we could somehow double its mass?

What would happen to Jupiter if we could somehow double its mass?

A) Its density would increase but its diameter would barely change.
B) Its density would decrease and its diameter would double.
C) It would become a star, with nuclear fusion in its core.
D) Its density would stay about the same and its volume would double.

Answer: A

Jupiter and the other jovian planets are sometimes called gas giants. In what sense is this term misleading?

Jupiter and the other jovian planets are sometimes called gas giants. In what sense is this term misleading?

A) The materials they are made of are not the kinds of thing we usually think of as gases.
B) Actually, it's a great description, because these worlds are big and gaseous throughout.
C) They are not in any sense "giants."
D) They actually contain relatively little material in a gaseous state.

Answer: D

Why is the radiation so intense in the region that traces Io's orbit around Jupiter (the Io torus)?

Why is the radiation so intense in the region that traces Io's orbit around Jupiter (the Io torus)? 

A) Jupiter's strong magnetic field makes the radiation intense everywhere, and the region around Io is no different than any other region.
B) The region is full of gases that become ionized after they are released from volcanoes on Io.
C) Io's gravity allows this region to capture huge numbers of charged particles from the solar wind.
D) An orbital resonance between Io, Europa, and Ganymede makes the radiation intense.

Answer: B

The cores of the terrestrial worlds are made mostly of metal because ________.

The cores of the terrestrial worlds are made mostly of metal because ________. 

A) the terrestrial worlds as a whole are made mostly of metal
B) metals sunk to the centers a long time ago when the interiors were molten throughout
C) over billions of years, convection gradually brought dense metals downward to the core
D) the core contained lots of radioactive elements that decayed into metals

Answer: B

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

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 hypothesis
B) a paradigm
C) a Ptolemaic model
D) a theory

Answer: D

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

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

A) I have a new theory about the cause of earthquakes, and I plan to start testing it soon.
B) I wrote a theory that is 152 pages long.
C) Einstein's theory of relativity has been tested and verified thousands of times.
D) Evolution is only a theory, so there's no reason to think it really happened.

Answer: C

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

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

A) Scientific explanations should be based solely on natural causes.
B) A scientific model must make testable predictions.
C) Science consists of proven theories that are understood to be true explanations of reality.
D) Science progresses through the creation and testing of models that explain observation as simply as possible.

Answer: C

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

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

A) inventing the telescope
B) showing that heavy objects fall at the same rate as lighter objects
C) proving Kepler's laws were correct
D) observing sunspots on the Sun and mountains on the Moon

Answer: D

All the following statements are true. Which one follows directly from Kepler's third law (P2= a3) ?

All the following statements are true. Which one follows directly from Kepler's third law (P2= a3) ?

A) Venus orbits the Sun at a slower average speed than Mercury.
B) Venus is more massive than Mercury.
C) Venus takes longer to rotate than it does to orbit the Sun.
D) Venus has a thicker atmosphere than Mercury.

Answer: A

According to Kepler's third law (P2= a3) how does a planet's mass affect its orbit around the Sun?

According to Kepler's third law (P2= a3) how does a planet's mass affect its orbit around the Sun?

A) A planet's mass has no effect on its orbit around the Sun.
B) More massive planets orbit the Sun at higher average speed.
C) More massive planets must have more circular orbits.
D) A more massive planet must have a larger semimajor axis.

Answer: A

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?

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?

A) Winter
B) Fall
C) Spring
D) Summer

Answer: A

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?

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?

A) Copernicus placed the planets in the wrong order going outward from the Sun.
B) Copernicus placed the Sun at the center, but did not realize that the Moon orbits the Earth.
C) Copernicus misjudged the distances between the planets.
D) Copernicus used perfect circles for the orbits of the planets.

Answer: D

The great contribution of Nicholas Copernicus was to ________.

The great contribution of Nicholas Copernicus was to ________. 

A) discover the laws of planetary motion
B) discover the law of gravity
C) prove that the Earth is not the center of the universe
D) create a detailed model of our solar system with the Sun rather than Earth at the center

Answer: D

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

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

A) they were the first people known to try to explain nature with models based on reason and mathematics, without resort to the supernatural
B) they were the only ancient culture that kept written records of their astronomical observations
C) they were the first people to realize that Earth is a planet orbiting the Sun
D) the books of every other culture were lost in the destruction of the library of Alexandria

Answer: A

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

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

A) developed the first scientific model of the universe
B) developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries
C) was the first to believe that all orbits are perfect circles
D) was the first to create a model of the solar system that placed the Sun rather than the Earth at the center

Answer: B

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

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

A) the seven most prominent constellations in the summer sky
B) the seven naked-eye objects that appear to move among the constellations
C) the names of the seven planets closest to the Sun
D) the names of prophets in the Bible

Answer: B

Scientific thinking is ________.

Scientific thinking is ________. 

A) an ancient mode of thinking first invented in Egypt
B) completely different from any other type of thinking
C) based on everyday ideas of observation and trial-and-error experiments
D) a difficult process that only a handful of people can do well

Answer: C

What practical value did astronomy offer to ancient civilizations?

What practical value did astronomy offer to ancient civilizations?

A) It allowed them to predict eclipses with great accuracy.
B) It helped them keep track of time and seasons, and it was used by some cultures for navigation.
C) It helped them understand our cosmic origins.
D) It helped them find uses for ancient structures like Stonehenge.

Answer: B

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

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

A) The model showed that apparent retrograde motion occurs as Earth passes by another planet in its orbit of the Sun.
B) The planets moved along small circles that moved on larger circles around the Earth.
C) The planets resided on giant spheres that sometimes turned clockwise and sometimes turned counterclockwise.
D) The planets sometimes stopped moving and then reversed to move backward along their circular orbits.

Answer: B

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

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

A) the bubbling and boiling of gases on the surfaces of stars
B) rapid changes in the brightnesses and colors of stars caused by changes in their spectra
C) light pollution
D) turbulence in the Earth's atmosphere

Answer: D

What do astronomers mean by light pollution?

What do astronomers mean by light pollution?

A) Light pollution is a type of air pollution created by lightweight gases such as hydrogen and helium.
B) Light pollution is a term used to describe the appearance of the sky in regions that are crowded with stars.
C) Light pollution means contamination of light caused by chemicals in the Earth's atmosphere.
D) Light pollution is light from human sources that makes it difficult to see the stars at night.

Answer: D

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

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

A) Telescopes have much more magnification and better angular resolution.
B) Telescopes collect more light and are unaffected by twinkling.
C) Telescopes can collect far more light with far greater magnification.
D) Telescopes can collect far more light with far better angular resolution.

Answer: D

What is the angular resolution of the human eye?

What is the angular resolution of the human eye? 

A) about 1 arcsecond (1/3600 of a degree)
B) about 1 degree
C) about 1 milliarcsecond
D) about 1 arcminute, or 1/60 of a degree

Answer: D

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

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

A) adaptive optics
B) a telescope
C) a diffraction grating
D) a flat glass mirror

Answer: C

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

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

A) wavicles
B) gamma rays
C) frequencies
D) photons

Answer: D

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

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

A) ultraviolet and X rays
B) infrared and radio
C) infrared and ultraviolet
D) visible light

Answer: B

The Chandra X-ray Observatory must operate in space because

The Chandra X-ray Observatory must operate in space because 

A) it was built by NASA.
B) X-ray telescopes require the use of grazing incidence mirrors.
C) X-rays are too dangerous to be allowed on the ground.
D) X rays do not penetrate Earth's atmosphere.

Answer: D

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

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

A) It can observe infrared and ultraviolet light, as well as visible light.
B) Stars do not twinkle when observed from space.
C) It never has to close because of cloudy skies.
D) It is closer to the stars.

Answer: D

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?

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?

A) Shifts in the wavelengths of spectral lines compared to the wavelengths of those same lines measured in a laboratory on Earth can tell us the star's speed toward or away from us.
B) The peak of the star's thermal emission tells us its temperature: hotter stars peak at shorter (bluer) wavelengths.
C) We can identify chemical elements present in the star by recognizing patterns of spectral lines that correspond to particular chemicals.
D) The total amount of light in the spectrum tells us the star's radius.

Answer: D

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?

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?

A) It is moving away from us.
B) Its surface is cooler than the surface of the Sun.
C) It is much more massive than the Sun.
D) It is much brighter than the Sun.

Answer: B

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

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

A) All the light emitted by hot object has higher energy than the light emitted by a cooler object.
B) A cold object produces more total infrared and radio emission per unit surface area than a hot object.
C) A hot object emits more radiation per unit surface area than a cool object.
D) A hot object produces more total infrared emission than a cooler object.

Answer: C

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

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

A) The cloud is cool and very dense, so that you cannot see any objects that lie behind it.
B) The cloud is cool and lies between you and a hot star.
C) The cloud is visible primarily because it reflects light from nearby stars.
D) The cloud is extremely hot.

Answer: B

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

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

A) X rays travel through space faster than radio waves.
B) X rays have higher frequency than radio waves.
C) X rays have shorter wavelengths than radio waves.
D) X rays and radio waves are both forms of light, or electromagnetic radiation.

Answer: A

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

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

A) Light is produced only when massive fields of electric and magnetic energy collide with one another.
B) The term electromagnetic wave arose for historical reasons, but we now know that light has nothing to do with either electricity or magnetism.
C) The passage of a light wave can cause electrically charged particles to move up and down.
D) Light can be produced only by electric or magnetic appliances.

Answer: C

What do astronomers mean by a constellation?

What do astronomers mean by a constellation? 

A) A constellation is a group of stars related through an ancient story.
B) A constellation is a region in the sky as seen from Earth.
C) A constellation is a group of stars that are all located in about the same place in space.
D) A constellation is any random grouping of stars in the sky.

Answer: B

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

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

A) The orbital plane of the Moon is tilted slightly (by about 5 degrees) to the ecliptic plane.
B) The Moon goes through a complete cycle of phases about every 29 1/2 days.
C) The nodes of the moon's orbit precess with an 18-year period.
D) The Moon is only about 1/4 as large as Earth in diameter.

Answer: A

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

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

A) It makes summer warmer in the Northern Hemisphere than in the Southern Hemisphere.
B) It causes the seasons to be more extreme than they would be if the Earth's distance from the Sun were always the same.
C) It is responsible for the fact that the seasons are opposite in the Northern and Southern hemispheres.
D) It doesn't; Earth's orbital distance plays no significant role in the seasons

Answer: D

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?

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?

A) Directly above Polaris
B) To the right of Polaris; that is, 90 degrees counterclockwise from its current position
C) To the left of Polaris; that is, 90 degrees clockwise from its current position
D) Still in the same place, below Polaris

Answer: B

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

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

A) dimmer
B) lower in the sky
C) brighter
D) higher in the sky

Answer: D

An angle of 1 arcsecond is ________.

An angle of 1 arcsecond is ________. 

A) slightly more than the width of a basketball held at arm's length
B) about the width of your fist held at arm's length
C) less than the thickness of a human hair held at arm's length
D) about the width of a finger held at arm's length

Answer: C

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

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

A) When we look in the sky, the stars all appear to be located on the celestial sphere.
B) The celestial sphere is another name for our universe.
C) The celestial sphere does not exist physically.
D) The Earth is placed at the center of the celestial sphere.

Answer: B

What is the ecliptic plane?

What is the ecliptic plane? 

A) The plane of the Milky Way Galaxy
B) The plane of Earth's orbit around the Sun
C) The plane of Earth's equator
D) The plane of the Sun's equator

Answer: B

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

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

A) Because the stars in the constellations are so far away.
B) Because the stars in the constellations are not moving.
C) Because the stars in the constellations all move at the same speeds and in the same directions, so they don't change their relative positions.
D) Because the stars in the constellations move so slowly-typically about the speed of a snail-that their motions are not noticeable.

Answer: A

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

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

A) It is between about 5% and 10% as old as the universe.
B) It is about 1% as old as the universe.
C) It is nearly the same age as the universe.
D) It is about one-third the age of the universe

Answer: D

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

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

A) about an hour ago
B) yesterday morning
C) about 6 months ago
D) about 3 weeks ago

Answer: B

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

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

A) Galaxy 1 must be twice as big as Galaxy 2
B) we are seeing Galaxy 1 as it looked at a later time in the history of the universe than Galaxy 2
C) Galaxy 2 must be twice as old as Galaxy 1
D) we are seeing Galaxy 1 as it looked at an earlier time in the history of the universe than Galaxy

Answer: D

When we look at an object that is 1000 light-years away, we see it ________

When we look at an object that is 1000 light-years away, we see it ________

A) as it was 1000 years ago
B) as it is right now, but 1000 times dimmer
C) looking just the same as our ancestors would have seen it 1000 years ago
D) as it was 1000 light-years ago

Answer: A

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

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

A) You, Earth, Milky Way Galaxy, solar system, Local Group, Local Supercluster, universe
B) You, Earth, solar system, Local Group, Local Supercluster, Milky Way Galaxy, universe
C) You, Earth, solar system, Local Group, Milky Way Galaxy, Local Supercluster, universe
D) You, Earth, solar system, Milky Way Galaxy, Local Group, Local Supercluster, universe
E) You, Earth, Local Group, Local Supercluster, solar system, Milky Way Galaxy, universe

Answer: D