Download Astro 001 Spring 2002

Astro 001 Final Fall 2002 Name_________________________ Section________
Unless otherwise stated, all questions are weighted equally or 2 points per question. 200
points = 100%.
The following sequence of questions has a total of 71 points.
(1) (Three points) Enumerate and describe at least two important properties of a
scientific model or theory.
(2) (Four points) What are some of the main reasons for the winter versus summer?
Identify and describe the major reasons.
(3) (Four points) What new things of phenomena did Galileo uncover when he used
the new telescope to look at the sky? For two more points, which of these had the
most impact in deciding between the Ptolemaic and Copernican theories of the
heavens?
(4) (Three points) What controls of the car directly impact or affect its acceleration?
Please explain.
(5) (Three points) Do the shapes of constellations change through time? Please
describe. Being specific in your thinking will help shape your answer.
(6) (Four points) Please enumerate Kirchhoff’s laws.
(7) (Four points) Which planets would a person on Mars never observe high in the
sky at night?
(8) (Two points) Which countries have landed people successfully on the moon?
(9) (Four points) Which planets in this solar system have rings?
(10)
(Four points) What is the diameter of the earth? The distance from the
earth to the moon? You may use either kilometers or miles to express your
answer.
(11)
(Four points) If a small planet were to have an atmosphere, which would it
be more likely to have hydrogen or carbon dioxide in its atmosphere? Explain.
(12)
(Four points) Please distinguish among meteoroids, meteors, and
meteorites.
(13)
(Six points) Describe a comet indicating its basic parts. You may
coordinate this with a sketch if you feel it is appropriate.
(14)
(Four points) Enumerate (list) and briefly describe the main processes of
heat transfer. Which ones are operating for the Sun?
(15) (Four
points) Which is the core of the Sun, a solid, liquid, gas, or plasma (hot gas
with the electrons stripped from the atoms)? Please explain.
(16)
(Four points) Describe how the Sun’s equilibrium is maintained.
(17) (Four
points) Name and describe the basic method used to measure the distance to
nearby stars. Some diagramming might be appropriate.
(18)
(Three points) What is the single most important property of a star that
determines the steps it goes through after ending its main sequence life?
(19)
(Three points) About how large will the Sun become when it reaches the red
giant stage?
Ten more definitions at two points each follow for a total of twenty points. Please define
the terms carefully for two points per term. You may use sketches or diagrams to
illustrate what you are talking about if you find that useful.:
(1) Occam’s razor:
(2) retrograde motion:
(3) Astronomical unit(AU):
(4) spectroscope:
(5) hydrostatic equilibrium:
(6) Galilean moons:
(7) gibbous (phase):
(8) escape velocity:
(9) pressure:
(10) Hertzsprung-Russell diagram:
Now for multiple choice questions at two points each:
(1) Polaris is unique because it
A. moves in a different direction than any other bright star.
B. is the brightest star in the sky.
C. twinkles more than any other bright star.
D. is fairly bright and shows very little motion when viewed from Earth.
E. [The premise if false. Polaris is not unique at all.]
(2) The Milky Way that we observe with the naked eye is
A. the path planets take across the sky.
B. debris left by the motions of planets.
C. debris left by comets.
D. the asteroid belt.
E. stars in the galaxy of which the Sun is a part.
F. sunlight scattered from water vapor in the atmosphere.
(3) As we watch the sky during the night, most of the stars move across the sky
A. from east to west.
B. from west to east.
C. from north to south.
D. from south to north.
(4) The smallest planet is
A. Earth . . . Saturn
B. Mercury . . . Earth
C. Pluto . . . Earth
D. Pluto . . . Jupiter
E. Earth . . . Jupiter
and the largest is
(5) The diameter of the Sun is about
A. one-tenth
B. one-half
C. the same as
D. 10 times
E. 100 times
the diameter of the largest planet.
(6) In astronomical units, how far is the Earth from the Sun?
A. 0.5
B. 1.0
C. 1.5
D. 3.0
E. 93,000,000
F.
(7) A light-year is defined as the
A. time required for light to travel from Earth to Sun.
B. distance to the nearest night-time star.
C. distance around the Earth’s orbit.
D. distance from the Earth to the sun.
E. distance light travels in one year.
(8) Which choice lists the objects in correct size from smallest to largest?
A. Earth, Sun, solar system, Galaxy
B. Sun, Earth, solar system, Galaxy
C. Earth, sun, Galaxy, solar system
D. Earth, Galaxy, Sun, solar system
E. [None of the above.]
.
(9) How does a star differ from a planet?
A. Most stars are smaller than planets.
B. Stars shine by their own light; planets don’t.
C. Stars move across the sky faster than planets.
D. Stars appear dimmer than planets.
E. Stars appear brighter than planets.
(10) If the plane of the Earth’s equator were not tilted with respect to the ecliptic plane,
A. the daylight period on Earth would be the same year-round.
B. there would be no seasonal variations on Earth.
C. Earth’s poles would not experience six-month-long nights.
D. [All of the above.]
(11) Ptolemy’s system of epicycles was used to explain the apparent
A. daily motion of the stars.
B. annual motion of the sun around the sky.
C. backward motion of the Moon through the sky.
D. changing speeds and directions of the planets among the stars.
E. motion of the Sun north and south of the celestial equator.
(12) Which of the planets known to the ancients can never be seen high overhead at
night?
A. Mercury and Venus only.
B. Mars, Jupiter, and Saturn only.
C. Saturn only.
D. Venus only.
E. [All of the planets can be seen high in the sky at some time of night.]
(13) What causes summer to be hotter than winter?
A. The Earth is closer to the Sun in summer.
B. The daylight period is longer in summer.
C. The Sun gets higher in the sky in summer.
D. [Both B and C above.]
E. [All of the above.]
(14) In Australia, the longest daylight period occurs in late
A. March.
B. June.
C. September.
D. December.
E. [No general statement can be made.]
(15) Which of the following planets appear(s) to move through the background of stars?
A. Venus
B. Mars
C. Jupiter
D. [Both A and B above.]
E. [All of the above.]
(16) The ecliptic and celestial equator intersect at two points called the
A. equinoxes.
B. solstices.
C. tropics.
D. sidereal points.
E. poles.
(17) In science, what is the difference between a theory and a hypothesis?
A. A hypothesis is more fully developed than a theory.
B. A theory is more fully developed than a hypothesis.
C. A hypothesis is based on a model, while a theory isn’t.
D. There is essentially no difference. The words are interchangeable.
(18) Eratosthenes calculated the size of the Earth from
A. angles to the Sun from locations a measured distance apart.
B. angles to the Moon from locations a measured distance apart.
C. its angular size and distance from the Sun.
D. its orbital speed and distance from the Sun.
E. its calculated rotational speed.
(19) A minute of arc is
A. a measure of how far the Sun moves during one minute of time.
B. one-sixtieth of a degree.
C. how far the Earth turns on its axis in one minute.
D. 60 degrees.
E. the angular diameter of the Sun.
(20) In ancient times, people distinguished the planets from the stars because
A. planets appear much brighter than any star.
B. features on planets’ surfaces could be seen whereas no star’s features could be
seen.
C. planets move relative to the stars.
D. planets differ in color from the stars.
E. planets can be seen during the day.
(21) Which of the following choices is not a criterion for a good scientific theory?
A. A theory should be aesthetically pleasing.
B. A theory should be agreed upon by all knowledgeable scientists.
C. A theory should fit present data.
D. [None of the above; all are criteria for a good theory.)
(22) The Copernican model explained retrograde motion as due to
A. planets moving along epicycles.
B. planets stopping their eastward motion, moving westward a while, and then
resuming their eastward motion.
C. different speeds of the Earth and another planet in their orbits.
D. [Both A and B above.]
E. [None of the above; the Copernican model was unable to explain retrograde
motion.]
(23) Why was Copernicus forced to use epicycles in his model?
A. To account for retrograde motion.
B. To account for phases of the Moon.
C. To accurately predict the position of a planet.
D. [Both A and B above.]
E. [All of the above.]
(24) The Sun appears to move among the stars. The Copernican model accounts for this
as being due to
A. the Earth’s rotation on its axis.
B. the Earth’s revolution around the Sun.
C. the actual motion of the Sun against distant stars.
D. the Earth changing speed in its orbit.
E. different planets moving at different speeds.
(25) The primary reason that it is hotter in Australia in December than it is in July is that
A. the southern Hemisphere is tilted toward the Sun in December.
B. the Earth is closer to the Sun in December than in July.
C. the Earth is moving faster in it sorbit in December than in July.
D. the earth is on the hotter side of the Sun in December.
E. [Both B and C above.]
(26) Kepler’s law of equal areas predicts that a planet moves fastest in its orbit when
A. it is closest to the Sun.
B. it is closest to the Earth.
C. the Earth, Moon, and sun are in a line.
D. it s farthest from the Sun.
E. [None of the above; the law makes no predictions as to speed.]
(27) If a new planet were found with a period of revolution of 6 years, what would be its
average distance from the Sun?
A. About 2 AU
B. About 3.3 AU
C. 6 AU
D. About 9 AU
E. 36 AU
(28) Using his newly invented telescope, Galileo discovered all of the following
except
A. moons of Jupiter.
B. phases of Venus.
C. sunspots.
D. stellar parallax.
E. mountains on the Moon.
(29) Which of the following planets can be seen (from Earth) in a crescent phase?
A. Mercury
B. Venus
C. Mars
D. [Two of the above.]
E. [All of the above.]
(30) Which of the following observations by Galileo was most convincing in deciding
between the two opposing theories of our planetary system?
A. moons of Jupiter
B. mountains on the moon
C. phases of Venus
D. sunspots
(31) If the same net force is applied to two different objects, one with a mass of 1 kg and
the other with a mass of 2 kg,
A. the 1-kg mass will have twice the acceleration of the other.
B. the 1-kg mass will have more acceleration than the other, but not necessarily
twice as much.
C. both objects will have the same acceleration, for the force determines the
acceleration.
(32) According to Newton, the natural motion of an object is
A. a circle.
B. an ellipse.
C. a straight line.
D. retrograde motion
(33) The gravitational attraction between an object and the Earth
A. stops just beyond the Earth’s atmosphere.
B. extends to about halfway to the moon.
C. extends about five-sixths of the way to the Moon.
D. extends to infinity.
(34) Which statement best describes the relationship between Newton’s laws and
Kepler’s laws?
A. Newton proved that Kepler was wrong.
B. Newton’s laws and Kepler’s laws are now considered equally valuable.
C. Newton’s laws are more fundamental and more powerful than Kepler’s laws.
D. Neither Newton’s laws nor Kepler’s laws have any modern applications.
(35) Newton checked his hypothesis concerning an inverse square law of gravitation by
calculating
A. the Moon’s acceleration toward the Earth.
B. the time required for the Moon to complete one orbit.
C. the mass of the Earth.
D. the mass of the Moon.
E. [Both C and D above.]
(36) The gravitational force due to the Moon is exerted
A. only upon the side of the Earth nearest the Moon.
B. only upon the point on the Earth nearest the Moon.
C. upon the center of the Earth only.
D. upon the entire Earth.
E. upon the water surfaces of the Earth but not upon the land surfaces.
(37) The principle of equivalence of the general theory of relativity tells us that
A. the force of gravity is equivalent to acceleration in the opposite direction.
B. speeds measured in any location are equivalent.
C. the speed of light is the same for all observers.
D. Newton’s laws are equivalent to Kepler’s laws.
E. Newton’s laws are equivalent to Einstein’s theories.
(38) Which of the following choices confirmed a prediction made by the general theory
of relativity?
A. Observations of Jupiter’s satellites.
B. Observations of phases of Venus.
C. Calculations of the orbit of Mercury.
D. Calculations predicting the existence of Mars’s moons.
E. [None of the above; general relativity has not been successful in astronomical
applications.]
(39) The frequency of visible light falls between that of
A. infrared waves and radio waves.
B. X-rays and cosmic rays.
C. ultraviolet waves and X-rays.
D. short radio waves and long radio waves.
E. ultraviolet waves and radio waves.
(40) Which of the following choices does not have the same fundamental nature as
visible light?
A. X-rays
B. Sound waves
C. Ultraviolet radiation
D. Infrared waves
E. Radio waves
(41) The solar spectrum is which of the following?
A. An absorption spectrum.
B. A continuous spectrum.
C. An emission spectrum.
D. [All of the above.]
E. [None of the above.]
(42) The Doppler effect causes light from a source moving away to be
A. shifted to shorter wavelengths.
B. shifted to longer wavelengths.
C. changed in velocity
D. [Both A and C above.]
E. [Both B and C above.]
(43) We can determine the elements in the atmosphere of star by examining
A. its color.
B. its absorption spectrum
C. the frequency at which it emits the most energy.
D. its temperature.
E. its motion relative to us.
(44) The Doppler effect is used to
A. measure the radial velocity of a star
B. detect and study binary stars.
C. Measure the rotation of the Sun.
D. [Two of the above.]
E. [All of the above.]
(45) The energy of a photon is directly proportional to the light's
A. Wavelength.
B. frequency.
C. velocity.
D. brightness.
(46) In the Bohr model of the atom, light is emitted from a atom when
A. an electron moves from an inner orbit to an outer orbit.
B. an atom gains energy,
C. an electron moves from an outer to an inner orbit.
D. one element reacts with another.
E. [Both A and B above.]
(47) Each element has its own characteristic spectrum because
A. the speed of light differs for each element.
B. some elements are at a higher temperature than others.
C. atoms combine to form molecules, releasing different wavelengths depending on the
elements involved.
D. electron energy levels are different for different elements.
E. hot solids, such a s tungsten, emit a continuous spectrum.
(48) Knowledge of which of the following quantities will allow us to calculate the
diameter of the Moon?
A. The Moon's distance and speed.
B. The Moon's angular size and speed.
C. The Moon's angular size and distance.
D. All three- distance, speed, and angular size - must be known.
E. [None of the above.]
(49) If the Moon was new last Saturday, what phase will it be this Saturday?
A. Waxing crescent.
B. Waxing gibbous.
C. At or very near first quarter.
D. At or very near full.
E. [Any of the above, depending upon other factors.]
(50) If you observe the Moon rising in the east as the Sun is setting in the west, then you
know that the phase of the Moon must be
A. new.
B. first quarter.
C. full.
D. third quarter.
E. [any of the above, depending upon other factors.]
(51) A lunar eclipse can occur
A. only around sunset.
B. only near midnight.
C. only near sunrise.
D. at any time of day or night.
(52) The density of an object is defined as
A. its thickness.
B. how much solid material the object contains.
C. its mass.
D. its volume.
E. the ratio of its mass to its volume.
(53) The Earth's atmosphere is made up of about
A. 80% oxygen and 20% nitrogen.
B. 50% oxygen and 50% nitrogen.
C. 20% oxygen and 80% nitrogen.
D. equal amounts of oxygen, nitrogen, and carbon dioxide.
E. equal amounts of oxygen, hydrogen, and carbon dioxide.
(54) Auroras result from
A. the Earth's magnetic field and its rotation.
B. the Earth's magnetic field and its revolution around the Sun.
C. the Earth's magnetic field and the solar wind.
D. the solar wind and the Sun's rotation.
E. the motion of the Moon around the Earth.
(55) Which of the following theories of the Moon's origin seem to fit the data best?
A. the capture theory.
B. the fission theory.
C. the double planet theory.
D. the large impact theory.
E. [Either A or C above.]
(56) Which planet is most massive?
A. Mercury
B. Mars
C. Earth
D. Jupiter
E. Saturn
(57) Whether a planet or moon has an atmosphere depends upon the planet’s (or moon’s)
A. orbital speed.
B. temperature.
C. escape velocity.
D. [Both A and C above.]
E. [Both B and C above.]
(58) Which of the following statements is true of all of the planets?
A. They rotate on their axes and revolve around the Sun.
B. They rotate in the same direction.
C. They have at least one moon.
D. Their axes point toward Polaris.
E. [More than one of the above is true of all of the planets.]
(59) Which of the following choices lists the four planets from smallest to largest?
A. Mars, Mercury, Earth, Uranus
B. Mercury, Uranus, Mars, Earth
C. Uranus, Mercury, Mars, Earth
D. Mars, Mercury, Earth, Uranus
E. [None of the above.]
(60) Compared to Jovian planets, terrestrial planets have a
A. more rocky composition.
B. lower density.
C. more rapid rotation.
D. larger size.
E. [More than one of the above.]
(61) Most asteroids orbit the Sun
A. between Earth and Mars.
B. between Mars and Jupiter.
C. between Jupiter and Saturn.
D. beyond the orbit of Saturn.
E. [None of the above. No general statement can be made.]
(62) Evolutionary theories now account for the slow rotation rate of the Sun by pointing
to
A. the slowing effect on the Sun of the solar wind.
B. friction within the gases involved, which would prevent the Sun from rotating
fast.
C. the effect of the inner planets on the Sun.
D. the effect of the large planetsparticularly Jupiteron the Sun.
E. the conservation of angular momentum, which predicts a slowly rotating Sun
when it formed.
(63) After the evolutionary theory of the formation of the solar system was proposed, it
was almost dismissed because it seemingly could not explain
A. planetary masses.
B. planetary distances from the Sun.
C. the existence of comets.
D. why some planetsparticularly Jupiterhave a strong magnetic field.
E. the observed rotation rate of the Sun.
(64) According to the evolutionary theories of solar system formation, the outer planets
contain much more hydrogen and helium than the inner planets because these elements
A. never fell in near the Sun.
B. condensed quickly to liquids and solids and remained far from the Fun.
C. were blown away from the inner solar system by the solar wind.
D. [Both A and B above.]
E. [All of the above.]
(65) The connection between comets and meteors is demonstrated when one sees
A. sporadic meteors on almost any night.
B. a comet in one part of the sky and meteors in another part of the sky on the same
night.
C. a predictable shower of meteors.
D. [None of the above; there is no connection.]
(66) Which of the following statements about Pluto is true?
A. It has two moons (that we know of).
B. Its orbit is within 2 degrees of the plane of the Earth’s orbit.
C. Its orbit is as circular as the Earth’s orbit.
D. We are confident that it was once a moon of Neptune.
E. [None of the above is true.]
(67) The discovery of asteroids depends on the fact that, compared to the stars, the
asteroids
A. look bigger.
B. look brighter.
C. move.
D. vary in brightness.
E. are a different color.
(68) The largest asteroid is closest to
in diameter.
A. 6 feet
B. 600 feet
C. 6 miles (10 km)
D. 600 miles (1000 km)
E. 60,000 miles (100,000 km)
(69) Which of the following statements best describes cometary orbits?
A. They are circular, lying in the plane of the ecliptic.
B. They lie between the orbits of Mars and Jupiter.
C. They are elongated ellipses tens to hundreds of astronomical units across.
D. They are within the orbit of Mercury.
(70) A comet’s tail
A. precedes its head through space.
B. follows its head through space.
C. is farther from the Sun than its head is.
D. is closer to the Sun than its head is.
E. [None of the above.]
(71) Why do most meteoroids not reach the surface of the Earth?
A. They bounce off the atmosphere and go back into space.
B. They burn up in the air.
C. They are light enough that they remain suspended in the air.
D. They land in the ocean 9since oceans cover most of the Earth).
E. [The statement is false; almost all reach the Earth, but they are not found.]
(72) Meteors are most easily seen after midnight because
A. the sky is darker then.
B. the Sun is closer to rising.
C. you are then on the “leading” side of the Earth.
D. meteor showers occur then.
E. [The statement is false; they are seen equally well anytime.]
(73) The Sun’s energy is generated by
A. gravitational contraction.
B. nuclear fission.
C. hydrogen fusion.
D. helium fusion.
E. chemical reactions.
(74) Sunspots are areas on the sun that are
A. hotter than their surrounds.
B. cooler than their surroundings.
C. brighter than their surroundings.
D. [Both A and B above.]
E. [Both B and C above.]
(75) Why is a high temperature needed for energy production in the core of the Sun?
A. Hydrogen will not combine with oxygen at a low temperature.
B. Energy is needed to overcome electrical repulsion.
C. Electrons will not recombine at low temperatures.
D. The force of gravity is greater at high temperatures.
E. Speeds are less at high temperature, so there is more time for reactions between
nuclei.
(76) The two forces producing hydrostatic equilibrium in the Sun to determine its size are
A. electrical forces and gravity.
B. nuclear forces and gravity.
C. electrical forces and gas pressure.
D. electrical forces and nuclear forces.
E. gravity and gas pressure.
(77) As the Sun “burns,”
A. its total mass decreases very slightly.
B. its total mass increases very slightly.
C. its energy decreases, but the Sun’s mass remains the same.
D. energy is produced, but the Sun’s mass remains the same.
E. [None of the above.]
(78) The total luminosity of the Sun can be calculated from its
A. rotation period and temperature.
B. rotation period and diameter.
C. diameter and distance from the Earth.
D. diameter and the solar energy at Earth’s distance.
E. distance from Earth and the solar energy detected at Earth’s distance.
(79) At any particular level within the Sun, the pressure outward is
A. less than the pressure inward.
B. equal to the pressure inward.
C. greater than the pressure inward.
D. [No general statement can be made.]
(80) The primary source of energy for the Sun is a series of nuclear reactions in which
A. four hydrogen nuclei fuse to form a helium nucleus.
B. a helium nucleus fissions to form four hydrogen nuclei.
C. uranium nuclei fission to form several other elements.
D. two nuclei fuse to form uranium or plutonium.
E. oxygen nuclei combine to form more massive nuclei.
(81) The photosphere is
A. the layer of the Sun where energy is created from mass.
B. the outermost layer of the Sun.
C. the layer of the Sun that we see when viewing the Sun.
D. the layer of the Sun in which we see granulation.
E. [Both C and D above.]
(82) The sun emits its most intense radiation in which region of the electromagnetic
spectrum?
A. Radio
B. Infrared
C. Visible
D. Ultraviolet
E. X-ray
(83) Suppose you observe a previously uninvestigated star and find its apparent
magnitude. To determine its absolute magnitude, you need to know the star’s
A. distance.
B. color.
C. velocity.
D. brightness as seen from Earth.
E. Doppler shift.
(84) The absolute magnitude of a star is
A. the same as the apparent magnitude.
B. equal to the greatest the apparent magnitude can be, in the case of a variable star.
C. equal to the apparent magnitude if the star is 10 parsecs away.
D. the size of a star from one side to the other.
E. equal to the brightness of the star on the clearest night.
(85) The distances to nearby stars can be measured by
A. comparing the apparent magnitudes of several stars.
B. bouncing radar pulses from their surfaces.
C. measuring the time it takes light to get here from them.
D. measuring their shifting motion against background stars through the year.
E. [Both B and C above.]
(86) If a star is 100 light-years away, what is its approximate distance in parsecs?
A. 3000 parsecs
B. 900 parsecs
C. 30 parsecs
D. 9 parsecs
E. 1/3 parsec
(87) Stars on the main sequence that have a small mass are
A. bright and hot.
B. dim and hot.
C. dim and cool.
D. bright and cool.
E. [Any of the above; there is no regular relationship.]
(88) To observe spectroscopic binaries, we rely on
A. knowing the composition of the individual stars.
B. our knowledge of the distance separating the stars.
C. our knowledge of the distances from Earth to the stars.
D. the change in light intensity as the stars orbit.
E. the Doppler effect.
(89) Binary star systems are especially important to us because they allow us to calculate
the
of stars.
A. compositions
B. proper motions
C. radial velocities
D. temperatures
E. masses
(90) Cepheid variables can be used to find distances because their
A. luminosity ifs related to their period.
B. radial velocity is related to their mass.
C. distance is related to their mass.
D. magnitude is related to their color.
E. period is related to their radial velocity.
(91) Considering only stars on the main sequence, the most massive stars are the
A. hottest and brightest.
B. hottest and dimmest.
C. coolest and brightest.
D. coolest and dimmest.
E. [No general statement can be made.]
(92) What is the difference between the Sun and a one-solar-mass white dwarf?
A. The Sun is larger.
B. The Sun has more hydrogen.
C. They have different energy sources.
D. [All of the above.]
E. ]None of the above.]
(93) If the rate of hydrogen fusion within the Sun were somehow to increase, the core
would
A. collapse and the Sun would grow cool.
B. collapse and heat up further.
C. expand and therefore tend to slow the fusion.
D. expand and therefore increase in temperature.
E. stay the same size but become hotter.
(94) Why does hydrogen fusion occur only in a star’s center?
A. Only near the center is there enough heat and pressure.
B. Only near the center is there enough hydrogen that is not mixed with other
elements.
C. Only near the center is the speed of light favorable for the reaction to occur.
D. Heat is transferred down to the center during the main sequence life of the star.
E. [The statement is false; fusion occurs throughout the star’s volume. This is what
causes the surface to be bright.]
(95) Why do massive stars run out of hydrogen in their cores faster than less massive
stars?
A. Their hydrogen fuses faster because of greater pressure.
B. There is less hydrogen in their cores.
C. The cores or less massive stars contain a greater percentage of helium, which
slows hydrogen fusion.
D. The cores of less massive stars contain a lesser percentage of helium, which slows
hydrogen fusion.
E. [The statement is false; more massive stars do not run out of hydrogen faster than
stars of less mass.]
(96) The Sun will at some time in the future become
A. a red giant.
B. a white dwarf.
C. a black dwarf.
D. [All of the above.]
E. [None of the above.]
(97) Red giants are more luminous than white dwarfs because
A. red giants are hotter.
B. red giants are closer.
C. red giants are larger.
D. [All of the above.]
E. [None of the above; the statement is not true.]
(98) What is the difference between the Sun and a one-solar-mass white dwarf?
A. The Sun is larger.
B. The Sun has more hydrogen.
C. They have different energy sources.
D. [All of the above.]
E. ]None of the above.]
(99) A planetary nebula is
A. the vastly expanded shell of a dying star.
B. a cloud of gas out of which stars form.
C. a cloud of cold dust in space.
D. the same as a white dwarf.
E. a circular ring around a black hole.
(100) The length of a star’s main sequence lifetime is determined by the star’s
A. carbon content.
B. distance from the center of the galaxy.
C. surface temperature.
D. mass.
E. spectral type.