AST1002 Multiple Choice
The temperature at the center of the Sun, where thermonuclear processes take place, is approximately 1.5 million K. 6000 K. 4500 K, as shown by sunspots. 1.5 × 107 K.
1.5 × 107 K.
1 arc second is equal to 1/60°. 1/360 of a full circle. 1/60 of a full circle. 1/3,600°.
1/3,600°.
The number of degrees in a semicircle is 90. 360. 57.3. 180.
180.
What is believed to be the solar mass of the black hole candidate at the center of the galaxy M87? 3 billion 300,000 3 million 300
3 billion
If the temperature of the solar surface is 5800 K and Wien's law for the peak wavelength of the spectrum of the Sun, assumed to be a blackbody, is given by λmax T = 2.9 × 106, with T in Kelvins and λ in nanometers (nm), what is the expected dominant wavelength of the Sun? 600 nm 50 nm 300 nm 500 nm
500 nm
The star α Centauri C and the star Groombridge 34 B have the same apparent magnitude, but α Centauri C is 1.3 pc away from Earth and Groombridge 34 B is 3.5 pc away. What is the luminosity of Groombridge 34 B compared with α Centauri C? 7.2 times fainter 2.7 times brighter 7.2 times brighter 2.7 times fainter
7.2 times brighter
In modern astronomy, the constellations are a small number of well-defined and separate groups of stars in our sky. 88 nonoverlapping sky regions, covering the whole sky. specific patterns of stars that point to certain directions that are useful for navigation. 13 specific regions of stars through which the planets and Moon appear to move in our sky.
88 nonoverlapping sky regions, covering the whole sky.
What is the major constituent of the atmosphere of Mars? H2 (hydrogen) CO2 (carbon dioxide) CH4 (methane or natural gas) H2O (water vapor)
CO2 (carbon dioxide)
The largest of the terrestrial planets is Jupiter. Venus. Mars. Earth.
Earth
The terrestrial planet whose atmosphere is composed primarily of nitrogen is Earth. Mars. Venus. Jupiter.
Earth
Which of the following statements correctly describes the surface of Earth? A thin, deformable crust allows the continents to slide over it. A thick, solid crust keeps the continents and ocean floors in fixed positions with respect to one another. Individual, solid crustal plates are pushed around by Earth's rotation and the tidal forces of the Moon and the Sun. Individual and separate solid crustal plates are pushed around by convective motion in the material of the underlying mantle.
Individual and separate solid crustal plates are pushed around by convective motion in the material of the underlying mantle.
The most likely origin of the "dirty snowballs" that become comets when they are deflected into orbits that bring them closer to the Sun is the dust and gas clouds in the Milky Way Galaxy. asteroid belt because most asteroids are actually comet nuclei. icy surfaces of the moons of Jupiter and Saturn. Kuiper belt and Oort cloud surrounding the solar system.
Kuiper belt and Oort cloud surrounding the solar system.
What is chromatic aberration in a telescope? Light of different colors reflecting from the objective mirror of the telescope comes to a focus at different points in front of the mirror. The objective lens varies in thickness from center to edge, and light passing through the different thicknesses suffers different amounts of absorption, thereby coloring the image. Light striking the lens at different distances from the center of the lens comes to a focus at different points inside the telescope. Light of different colors comes to a focus at different points behind the objective lens inside the telescope.
Light of different colors comes to a focus at different points behind the objective lens inside the telescope.
The most likely mechanism for the solar system is that the Sun captured the planets as they drifted through space. Sun and planets slowly condensed to their present form from a gas and dust cloud. solar system was once a galaxy from which the Sun and planets are the remnants, after evolution. planets were spun out of the Sun as smaller gas clouds and subsequently condensed.
Sun and planets slowly condensed to their present form from a gas and dust cloud.
The Copernican system for planetary motions is Earth-centered, with the planets moving in epicycles around the Earth. Sun-centered, with the planets moving in elliptical orbits and the Sun at one focus of the ellipse. Sun-centered, with the planets moving in perfect circles around the Sun. Earth-centered, with the planets, the Sun, and the stars mounted on crystal spheres, pivoted to allow the correct motions around the Earth.
Sun-centered, with the planets moving in perfect circles around the Sun.
The density of Mercury is about the same as that of the Earth, but Mercury contains a larger proportion of iron. How is this possible? Mercury has only 1/18 the Earth's mass. Thus it must be composed of heavier materials (like iron) in order to match the Earth's density. The Earth contains, proportionally, a smaller volume of iron, but because of Earth's greater mass, the Earth's iron has been compressed to a higher density than the iron on Mercury. The inner core of Mercury is hollow, thus reducing the overall density much below that of iron. The iron in Mercury's core is accompanied by a very low-density crust. The average density is thus comparable to the density of the Earth.
The Earth contains, proportionally, a smaller volume of iron, but because of Earth's greater mass, the Earth's iron has been compressed to a higher density than the iron on Mercury.
What is the explanation for the bright cells of photospheric gases that make up the cellular granulation pattern seen on the visible surface of the Sun? The cells are regions of nuclear energy generation in the Sun's photosphere. Each cell is a region of strong magnetic field, which compresses and heats the gas within it. The cells are the base of a circulation pattern that extends from the photosphere to the outer corona. The cells are the tops of blobs of hot gas that have risen from the Sun's convective zone.
The cells are the tops of blobs of hot gas that have risen from the Sun's convective zone.
The end of the life of a red dwarf star is predicted to be a sphere of almost pure helium. But no such spheres have been detected. What do we believe is the reason? Helium is a relatively light material, so these helium spheres are expected to dissipate in a short time. These helium stars are very dim and consequently hard to detect. The evolution rate for red dwarfs is so slow that none has yet evolved to its end stage. There are very few red dwarfs, so their end products are expected to be rare.
The evolution rate for red dwarfs is so slow that none has yet evolved to its end stage.
A theory of the origin of the solar system must take into account all important general properties of the planets, which include three of the four properties listed. Which one is NOT an important general property of the planets? The planets are grouped by size and composition into two general groups: terrestrial and Jovian. All the planets orbit the Sun in the same direction and nearly in the same plane. The magnetic fields of the planets are produced by a variety of mechanisms. The terrestrial planets all orbit much closer to the Sun than do any of the Jovian planets.
The magnetic fields of the planets are produced by a variety of mechanisms.
The outer cores of Jupiter and Saturn are made of "ices" that are actually in the liquid state. Why are they not solid? The material of the ices is hydrogen and helium, which cannot exist in a solid form. The constant agitation caused by the planets' rotation prevents the formation of a solid. The temperature in the outer cores of Jupiter and Saturn is too high. The pressure in the outer cores of Jupiter and Saturn is too great.
The temperature in the outer cores of Jupiter and Saturn is too high.
For Balmer series lines to show up strongly in absorption in stellar spectra, significant numbers of hydrogen atoms have to have electrons in the n = 2 energy level. What then does the appearance of these lines in a stellar spectrum tell us about the temperature of the star's surface? The appearance of the lines tells us very little about the temperature because hydrogen gas will show significant Balmer absorption, whatever the surface temperature. The temperature must be reasonably low so that no atoms will have electrons excited beyond this energy level (e.g., to n = 3). The temperature must be reasonably high to excite the electrons to this level by collisions but not high enough to ionize the atoms. The temperature must be high enough to ionize the hydrogen atoms by collision in order that they can absorb from this level.
The temperature must be reasonably high to excite the electrons to this level by collisions but not high enough to ionize the atoms.
What happens to the wavelength of light as it travels outward through the gravitational field of a planet or star so that the field becomes less strong? The wavelength decreases. The wavelength stays the same, but the intensity of the light decreases. The wavelength stays the same, but the energy of each photon decreases. The wavelength increases.
The wavelength increases.
The brightest stars in the Pleiades cluster are not on the main sequence but away from it toward the upper right. Explain this with respect to Hertzsprung Diagram. The brightest stars have already become white dwarf stars, as shown by their position. The brightest stars have not yet reached the main sequence and are in the T Tauri phase. These blue supergiant stars have already begun to evolve toward the red supergiant phase. The brightest stars have already evolved through the red giant phase and have now returned to the blue giant phase on their way to the white dwarf phase.
These blue supergiant stars have already begun to evolve toward the red supergiant phase.
Who first proved that light is a wave? James Clerk Maxwell Thomas Young Albert Einstein Isaac Newton
Thomas Young
Why is the Moon in a synchronous orbit around Earth, always keeping the same face toward Earth? As the Moon rotates, friction between the Moon's large liquid interior and its mantle has slowed the rate of rotation until it just matches the orbital rate. Over time it will slow further, and then the Moon will no longer be in a synchronous orbit. There is a strong magnetic attraction between the two bodies that keeps the Moon turned toward Earth. When the Moon was molten and experienced chemical differentiation, the gravitational pull of Earth caused large tides. The friction created as Earth's gravity attempted to keep the high tide bulge pointed toward Earth resulted in the Moon's rotation being slowed, causing it always to face Earth. The Moon must rotate on its axis at the same rate it orbits Earth to conserve angular momentum.
When the Moon was molten and experienced chemical differentiation, the gravitational pull of Earth caused large tides. The friction created as Earth's gravity attempted to keep the high tide bulge pointed toward Earth resulted in the Moon's rotation being slowed, causing it always to face Earth.
Most interstellar matter is too cold to be observed optically. Its radiation is predominantly emitted at longer wavelengths, such as infrared and radio. This behavior is an example of Wien's law. the Stefan-Boltzmann law. Bode's law. Kirchhoff's law.
Wien's law.
Are the constellations seasonal? Yes. As the year progresses, the constellations change their positions with respect to each other, so every night brings a different mixture of summer and winter constellations. Yes. On a summer night many of the constellations you can see are different from the constellations you can see on a winter night. But there are some constellations you can see all year long. Yes. On a summer night all the constellations you can see are different from the constellations you can see on a winter night. No. If you wait long enough, you can see all the constellations on any clear night of the year.
Yes. On a summer night many of the constellations you can see are different from the constellations you can see on a winter night. But there are some constellations you can see all year long.
Could the gold in the jewelry you are wearing have any connection with neutron stars? No. We do not expect neutron stars to eject any significant amount of material into the Galaxy. No. Some of the hydrogen in Earth's water may have been ejected from neutron stars as high-energy protons, but all heavy elements come from supernova explosions of normal stars. Yes. Some of the gold may have been created in collisions between neutron stars in binary systems. Yes. The neutrons in the gold nuclei were very likely ejected from individual neutron stars.
Yes. Some of the gold may have been created in collisions between neutron stars in binary systems.
How quickly is the Moon spiraling away from Earth? a few centimeters per year a few centimeters per century The Moon is not moving away from Earth because its orbit is governed by Newton's laws. a few centimeters per million years
a few centimeters per year
What is the diameter of Mare Imbrium, the largest lunar "sea," compared with the diameter of the Moon itself? about 1/100 the diameter of the Moon about 1/3 the diameter of the Moon just over 1/2 the diameter of the Moon about 1/10 the diameter of the Moon
about 1/3 the diameter of the Moon
The manner in which the terrestrial planets formed was the gravitational condensation of gas, followed by the capture of solid planetesimals. accretion of planetesimals to form a core, followed by the gravitational capture of gas from the solar nebula. accretion of solid planetesimals containing mostly rocky material. gravitational condensation of hydrogen, helium, and dust in eddies or vortices in the solar nebula.
accretion of solid planetesimals containing mostly rocky material.
Stars in a binary system are useful in studying mass transfers because we know that the two stars have the same radius. mass. spectral type. age.
age
The first pulsar was discovered by Albert Einstein in 1905. the Astronomer Royal in Newton's time, Sir Edmund Halley, in 1606. Galileo Galilei in 1610. an English graduate student, Jocelyn Bell, in 1967.
an English graduate student, Jocelyn Bell, in 1967.
The type of rock that makes up the lunar highlands is basalt. granite. anorthosite. limestone.
anorthosite
For most stars, the chances are about even of the apparent magnitude being larger or the absolute magnitude being larger. absolute magnitude and the apparent magnitude are numerically equal. apparent magnitude is a larger number than the absolute magnitude. absolute magnitude is a larger number than the apparent magnitude.
apparent magnitude is a larger number than the absolute magnitude.
The light-gathering power of a telescope depends directly on the focal length of its primary mirror or lens. area of its primary mirror or lens. ratio of the focal lengths of its primary element (mirror or lens) and its eyepiece. area of the final aperture of its eyepiece.
area of its primary mirror or lens.
What is a CCD (charge-coupled device)? device in which an image from a photographic plate or film is transferred to a computer by moving static electric charges directly into the computer memory in a manner similar to modern copying machines array of small light-sensitive elements that can be used in place of photographic film to obtain and store a picture detector in which a small electric current is controlled by a bimetallic strip that expands and contracts in response to infrared radiation electronic filter to single out one wavelength or set of wavelengths for studying astronomical objects
array of small light-sensitive elements that can be used in place of photographic film to obtain and store a picture
Where is a planet when it is moving most rapidly in its orbit? at the focus of its orbit at aphelion approaching the closest distance to the Sun at perihelion
at perihelion
If the mass of the Sun were doubled and Jupiter remained at its present distance, the gravitational force the Sun exerted on Jupiter would stay the same. be 16 times its present value. be twice its present value. be 4 times its present value.
be twice its present value
How was the black hole candidate Cygnus X-1 first discovered? by extremely high spatial resolution radio observations with the VLA radio interferometric array in New Mexico by infrared observations with the IRAS infrared satellite by X-ray measurements with the Uhuru satellite by high-resolution visible-light observations with the Hubble Space Telescope
by X-ray measurements with the Uhuru satellite
Nuclear fusion reactions of helium produce primarily iron nuclei. carbon and oxygen nuclei. nitrogen and neon nuclei. beryllium and lithium nuclei.
carbon and oxygen nuclei.
Which major constituent of the atmospheres of Venus and Mars is present in only very small amounts in Earth's atmosphere? nitrogen, N2 methane, CH4 oxygen, O2 carbon dioxide, CO2
carbon dioxide, CO2
Which meteorites are believed to be samples of primordial solar nebula material? stony irons irons meteorites showing Widmanstätten patterns when etched with acid carbonaceous chondrites
carbonaceous chondrites
The heat energy that powers tectonic activity on the surface of Earth originates deep in Earth's core. How does this energy move from the core to the surface? conduction through the solid lower mantle and convection in the upper mantle (asthenosphere) conduction throughout the entire mantle convection throughout the entire mantle steady flow of hot magna from Earth's core through cracks in the mantle to the lithosphere
conduction through the solid lower mantle and convection in the upper mantle (asthenosphere)
The star Arcturus is classified as K2 III, which means that it is a cool main-sequence star. hot giant. cool supergiant. cool giant.
cool giant.
The spectral luminosity class of the star Spica is B1 V, and that of the star τ Ceti is G8 V. From this information, we know that Ceti is _____ Spica. hotter but has the same luminosity as hotter and has a lower luminosity than cooler but has the same luminosity as cooler and has a lower luminosity than
cooler and has a lower luminosity than
Parallax of a nearby star is used to estimate its distance from Earth. physical size or diameter. apparent magnitude. surface temperature.
distance from Earth.
A sequence of thermonuclear fusion processes inside massive stars can continue to transform the nuclei of elements such as carbon and oxygen into heavier nuclei and also generate excess energy up to a limit beyond which no further energy-producing reactions can occur. The element that is produced when this limit is reached is iron. uranium. silicon. oxygen.
iron
If you face Polaris, the North Star, you are facing north; west is to your right and east is to your left, whether you are in the northern hemisphere or not. east is to your right and west is to your left, whether you are in the northern hemisphere or not. east is to your right and west is to your left, but only if you are in the northern hemisphere. west is to your right and east is to your left, but only if you are in the northern hemisphere.
east is to your right and west is to your left, whether you are in the northern hemisphere or not.
The magnetic field of Earth is caused by a solid iron magnet inside Earth. the motion of electrically charged particles in the solar wind blowing around Earth. electric currents flowing in the high atmosphere (ionosphere) of Earth. electric currents flowing in the molten core.
electric currents flowing in the molten core.
What is believed to be the composition of Earth's core? essentially pure iron about half iron and half lighter elements about 80% iron and 20% lighter elements about iron and lighter elements
essentially pure iron
How much of the overall sky is north of the celestial equator? more than one-half because of the precession of the poles less than one-half because of the tilt of the equator to the ecliptic plane all of it, by definition exactly one-half
exactly one-half
In the search for planets around other stars, which of the following possible lines of evidence has NOT yet been seen? faint pinpoints of light slowly circling a star warped disk of dust and gas around a young star cyclic Doppler shift variations in a star's spectrum wavy path of a star through space, as if the star were being tugged by an orbiting planet
faint pinpoints of light slowly circling a star
Earth has an average density that is approximately more than ten times that of water. equal to that of water. five times that of water. twice that of water
five times that of water.
What mechanism controls the direction in which a comet's ion tail is aligned in space? tail's direction of motion because the tail simply trails behind the comet in its orbit gravitational attraction of the tail material toward the giant planet Jupiter gravitational attraction of the tail material toward the Sun flow of solar wind past the comet's head
flow of solar wind past the comet's head
What is the basic structure of Earth's atmosphere? four layers of alternating temperature profiles: temperature decreasing, then increasing, then decreasing, then increasing with altitude two layers: temperature decreasing with increasing altitude in the lower layer, then increasing with increasing altitude in the upper layer single layer of smoothly decreasing temperature with increasing altitude single layer of smoothly increasing temperature with increasing altitude
four layers of alternating temperature profiles: temperature decreasing, then increasing, then decreasing, then increasing with altitude
What are neap tides? high tides that are significantly higher than the average high tide any high tides high tides that are significantly lower than the average high tide any low tides
high tides that are significantly lower than the average high tide
Which one of the following descriptions of Miranda, one of the satellites of Uranus, is correct? icy surface with chaotically varied terrain heavily cratered, icy surface with deformation and flowing due to heating in some regions icy, frost-covered surface with vents of rising gas visible in the northern hemisphere rocky surface with active volcanoes
icy surface with chaotically varied terrain
Which of the following phenomena is NOT seen on Jupiter's satellite Io? sulfur dioxide frost lava flows impact craters volcanic plumes
impact craters
Where in the northern hemisphere is the aurora, or northern lights, most often found? only at the midnight position along a line of longitude from the equator to the North Pole in a small patch at the magnetic north pole in a circular region around the magnetic north pole only at the midday position over the polar region, when the direct sunlight excites the air to emit light
in a circular region around the magnetic north pole
How is gas distributed in interstellar space? concentrated around existing stars because of the stars' gravitational pull uniformly distributed through space in clumps, concentrated in interstellar clouds concentrated in narrow riverlike streams of gas that extend across the Galaxy
in clumps, concentrated in interstellar clouds
Where is most of the mass of the Sun concentrated? spread uniformly throughout the Sun in the convective zone in the inner core in the photosphere
in the inner core
Earth's mantle, the semimolten layer below the crust, is composed largely of what chemical materials? iron-poor rocks and minerals minerals rich in iron and magnesium amost pure iron solid hydrogen and helium
minerals rich in iron and magnesium
The surfaces of Ida, Mathilde, and Eros, asteroids photographed by the Galileo and NEAR Shoemaker spacecraft are covered with young, sharp, jagged protrusions, due to fragmentation by collision with other asteroids, and few craters. irregular, somewhat rounded, and moderately cratered. covered with ice that is criss-crossed with cracks and systems of parallel grooves. densely covered with ancient large and small overlapping craters, similar to the surface of the highland areas of the Moon.
irregular, somewhat rounded, and moderately cratered.
In Newton's law of universal gravitation, F = GMm/R2, which defines the force between Earth with mass M and an orbiting satellite of mass m at a distance R from Earth, G depends on the material occupying the space between the two objects. is variable, depending on the masses of the two objects. is a constant, throughout all measured space and time. depends on the speed of motion of the satellite.
is a constant, throughout all measured space and time.
One of the characteristics of the magnetic field of Uranus is that its axis is aligned almost parallel to the planet's axis of rotation but is offset from the planet's center. is aligned almost exactly along the planet's axis of rotation, through the center of Uranus. is tilted almost 60° to the axis of planetary rotation and is offset from the planet's center. passes through the center of Uranus but is tilted almost 60° from the axis of rotation.
is tilted almost 60° to the axis of planetary rotation and is offset from the planet's center.
In its orbit around Earth, the Moon rotates once every 24 hours to keep in step with Earth. keeps the same side toward the Sun. keeps the sunlit side toward Earth. keeps the same side toward Earth.
keeps the same side toward Earth.
The word chromosphere refers to a light-emitting region just outside the event horizon of a black hole. layer in the Sun's atmosphere. dense, spherical interstellar cloud of glowing gas. layer in Earth's atmosphere just below the ionosphere.
layer in the Sun's atmosphere.
What is the lunar regolith? layer of fine powder covering the lunar surface deeper part of the lunar crust that has not been extensively cracked by impacts part of the lunar surface that is not covered with lava flows lunar crust and mantle together
layer of fine powder covering the lunar surface
In which of the following physical characteristics are the Earth and Mars most similar to each other? number of moons planetary diameter length of solar day total mass
length of solar day
The celestial equator is defined as the band of constellations through which the Sun and Moon move in our sky. line traced in the sky by the Moon each month against the background stars. line traced in the sky by the Sun over one year against the background stars. line in the sky that is perpendicular to Earth's spin axis.
line in the sky that is perpendicular to Earth's spin axis.
Which of the following scientific approaches has NOT yet been exploited for the study of the deep interior of Earth? study of lavas from volcanoes such as those on Hawaii manned deep-drill projects started from extensive caves beneath Earth's surface measurements of seismic waves from earthquakes magnetic field studies
manned deep-drill projects started from extensive caves beneath Earth's surface
What method is used by astronomers to infer the existence in space of a dark object of about 5 solar masses, such as a black hole? measurement of the gravitational redshift of spectral lines in the spectrum of the object estimation of the luminosity of the object and the application of the mass-luminosity relationship measurement of the effect of its gravitational force on a companion object in a binary system infrared imaging of a region whose effective temperature is lower than the cosmic microwave background, rendering it dark
measurement of the effect of its gravitational force on a companion object in a binary system
The coldest layer of Earth's atmosphere is located between stratosphere and mesosphere. troposphere and stratosphere. troposphere and Earth's surface. mesosphere and thermosphere.
mesosphere and thermosphere.
The inner two Galilean satellites of Jupiter differ from the outer two by having much lower average densities and heavily cratered surfaces. almost the same average densities but much older, more heavily cratered surfaces. almost the same average densities but much younger, less-cratered surfaces. much higher average densities and almost crater-free surfaces.
much higher average densities and almost crater-free surfaces.
An atom consists of: neutrons orbiting an electrically neutral nucleus composed of protons and electrons. positive protons, neutral neutrons, and negative electrons orbiting a small but massive black hole. negatively charged electrons and positively charged protons mixed uniformly throughout the volume of the atom. negatively charged electrons moving around a very small but massive, positively charged nucleus.
negatively charged electrons moving around a very small but massive, positively charged nucleus.
A black hole is so named because it emits no visible light because it is so cold, less than 100 K. no light can escape from it due to its powerful gravitational field. the gravitational field is so high that the wavelength of its emitted light is gravitationally redshifted to radio wavelengths. it is colder that the rest of the universe; that is, its effective temperature is less than 3 K.
no light can escape from it due to its powerful gravitational field.
Spacecraft measurements near Venus indicate that the planet has a magnetic field that varies in concert with the 11-year solar activity cycle and is linked to it via the solar wind. a very powerful magnetic field, much stronger than that of the Earth. no planetwide magnetic field. a variable planetwide magnetic field like the Earth.
no planetwide magnetic field.
Moonquakes never occur; the Moon is seismically quiet. are much more violent and occur much more often than earthquakes. occur but are much weaker and much less frequent than earthquakes. occur but only from the impact of meteoroids from space.
occur but are much weaker and much less frequent than earthquakes.
The main component of primary cosmic rays is nuclei of heavy elements such as carbon and iron. electrons. gamma rays. protons.
protons.
Which of the following objects is NOT an end point of a star's evolutionary life? neutron star red giant black hole supernova
red giant
A star on the asymptotic giant branch (AGB) is a red supergiant. cool main-sequence star. blue supergiant. star in its first red-giant phase.
red supergiant.
In the system of celestial coordinates that matches latitude and longitude on the Earth, which is the coordinate that is equivalent to longitude? right ascension declination elongation angle precession
right ascension
The mantle of Earth is composed of iron. water. atmospheric gases. rock.
rock.
The asteroid belt is believed by most astronomers to be composed of the remnants of a gaseous planet disrupted by a massive impact. genuine leather. rather dirty ice balls similar to the nuclei of comets. rocky debris left over from the formation of the solar system.
rocky debris left over from the formation of the solar system.
According to Kirchhoff's laws, the continuous spectrum of light from a hot star, after passing through a cool gas cloud, is unaffected because atoms in the gas cloud are too cool to absorb or emit energy. is enhanced at infrared wavelengths by a continuous spectrum emitted by the cool gas. shows absorption features where light has been absorbed by the atoms of the cool gas. contains additional emission lines from energy emitted by the atoms of the cool gas.
shows absorption features where light has been absorbed by the atoms of the cool gas.
How many times have human beings landed on the Moon? six times seven times four times five times
six times
In the geocentric model for the solar system developed by Ptolemy, to what does the word epicycle refer? large circle (orbit) that carries the planet around the Earth while the planet itself is moving in a smaller circle small circle about which a planet moves while the center of this circle moves around the Earth length of time from when the planet is farthest from the Earth to the next time it is farthest from the Earth complete cycle of planetary motions after which the motions repeat themselves (almost) exactly
small circle about which a planet moves while the center of this circle moves around the Earth
Before the Mars-sized impactor struck Earth to cause ejecta that formed the Moon, Earth probably had a _____ density and _____ rotation rate than it does now. greater; slower smaller; faster greater; faster smaller; slower
smaller; slower
If a modern astronomer describes a faint star as being in the constellation Cygnus, the Swan, you know that the star is in a distant galaxy located in a particular direction from the Earth. one of a set of stars that make up a particular "picture," in this case a swan, in the sky. somewhere within a particular region of sky having definite boundaries. inside our solar system.
somewhere within a particular region of sky having definite boundaries.
Sometimes high tides are higher than at other times. What name is given to the highest high tides? Yule tides neap tides rip tides spring tides
spring tides
The study of stars in clusters has especially helped astronomers to understand stellar evolution, the development of stars with time. the action of nuclear fusion in stars. the reason for differences in surface temperatures of stars. the mechanism of mass loss in stars.
stellar evolution, the development of stars with time.
Mars moves in an elliptical orbit around the Sun. The Sun is located at the focus of the ellipse that is closer to the point where Mars moves fastest. the exact center of the ellipse. the focus of the ellipse that is closer to the point where Mars moves slowest. one end of the major axis of the ellipse.
the focus of the ellipse that is closer to the point where Mars moves fastest.
Main-sequence stars apparently are not larger than a few hundred solar masses. The reason stars of larger mass do not exist is that such stars contract directly to become planetlike objects. interstellar clouds of greater mass break up to become binary or multiple-star systems, not single stars. the thermonuclear reactions in such stars proceed so rapidly that the stars explode. their temperature becomes so high that they are disrupted by the pressure of radiation inside them.
their temperature becomes so high that they are disrupted by the pressure of radiation inside them.
The scientific method is a major force in science, and theories describing physical phenomena have been developed with the aim of ensuring that they agree with what we find in experiments and observations. they agree with the wisdom of the ancients. they are so good and our faith in them is so strong that we never need to test them against observations. results from experiments can be adjusted to agree with carefully constructed theoretical ideals.
they agree with what we find in experiments and observations.
On a topographical map of Venus, how many large "continents" of high ground rise above the flat plains? two none one seven
two
What are the Van Allen belts? inner and outer parts of the asteroid belt regions of high concentration of electrons and ionized atoms in Earth's upper atmosphere where radio waves are reflected toward the surface of Earth two doughnut-shaped regions of high-energy charged particles in Earth's magnetosphere oval-shaped region around each of Earth's magnetic poles where charged particles collide with ions in Earth's atmosphere
two doughnut-shaped regions of high-energy charged particles in Earth's magnetosphere
The Lyman-alpha spectral line of hydrogen has a wavelength of 121.6 nm. In which wavelength band does this line occur? ultraviolet X rays infrared visible light
ultraviolet
Retrograde motion of a planet is westward motion against the star background. eastward motion against the star background. eastward motion with respect to the Moon. westward motion with respect to the foreground on the Earth.
westward motion against the star background.
In the simplified version of Kepler's third law, P2 = a3, the units of the orbital period P and the semimajor axis of the ellipse a must be, respectively, years and meters. years and astronomical units. seconds and meters. years and light-years.
years and astronomical units.
