ASTRON 40835

subject Type Homework Help
subject Pages 26
subject Words 3140
subject Authors Eric Chaisson, Steve McMillan

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Due to our ozone layer, ultraviolet astronomy must be done from space.
Only high-energy gamma rays can escape the event horizon of a black hole.
Mercury's magnetic field is generated by the same dynamo effect as Earth's.
Neutrinos can move faster than c, the speed of light, as was discovered in SN1987A in
1987.
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The probes sent out of our solar system were carefully designed to hide any trace of
their origin.
The haphazard terrain of Miranda suggests it was broken up by impact after it had
differentiated, then fell back together as a jumbled maze.
Venus and Mercury both have magnetic fields similar to Earth's.
The Moon and the crustal rocks of Earth are similar in density.
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Today most scientists favor the capture theory of the Moon's origin, since it would
explain why the Moon still orbits in the ecliptic plane, as do other planets.
Due to its larger mass, the Sun's gravitational effect on Earth's tides is greater than the
Moon's.
Around Sun-like stars, we have, to date, only found Jupiter-like planets.
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Among the ellipticals, E0 types look the most like huge globular star clusters.
On average, elliptical galaxies are richer star forming regions than spirals.
Both spiral and elliptical galaxies seem to have dark haloes of similar proportions
relative to their visible matter.
During the epoch of decoupling, nuclei and electrons combined to form atoms.
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Shapley found the globular clusters were strongly concentrated toward Sagittarius.
Jupiter's Great Red Spot is similar to a hurricane on Earth except for its size.
When Cassini entered orbit around Saturn, it caused the planet's orbit to change.
A star of the same diameter, but twice as hot as our Sun, must be 16 times more
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luminous.
Most bright blue stars we see with the naked eye are good candidates for life, since they
have much larger habitable zones than does the Sun.
The central engine of an active galaxy is less than a parsec in diameter.
Jupiter puts back into space twice the energy it gets from the Sun.
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Our Sun will first become a red giant, then a white dwarf, and finally a brown dwarf.
Kepler relied heavily on the telescopic observations of Galileo in developing his laws of
planetary motion.
Fewer than 100 stars lie within 5 parsecs of the Sun.
As they move through space, the vibrating electrical and magnetic fields of a light wave
must move perpendicular to each other.
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Although water and ammonia can produce Jupiter's white clouds, the complex
coloration we observe in Jupiter's atmosphere requires more complex chemistry.
According to Wein's law, the higher the surface temperature of a star, the redder its
color.
The orbit of the Solar System around the Galaxy is similar to that of a planet, almost
circular and in the galactic plane.
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The largest known galaxies contain about 10 billion solar masses.
On average, the Moon orbits Earth from a distance of about 30 Earth radii.
Main sequence stars are fusing hydrogen into helium in their cores.
The pressure in the photosphere affects the width of spectral lines.
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Although it is almost the same size as Jupiter, Saturn's gravity is about 2.5 times less,
because of Saturn's lower mass and density.
In the scientific method, it is not necessary to test your theory.
The Moon's lower density indicates it has a smaller concentration of iron in its core, as
does the absence of a lunar magnetic field.
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The fact that we don't see very many Earthlike planets in orbit around other stars is an
indication that Earthlike planets are rare.
Because they all involve the detonation of a carbon-rich white dwarf at the
Chandrasekhar limit, all Type I supernovae are approximately equally luminous.
The mass of a newly formed star will determine its position on the main sequence.
A radio galaxy whose lobes are swept back as if forming a tail probably indicates
A) evidence for intergalactic matter.
B) the galaxy is about to evolve into a spiral.
C) the galaxy is isolated, not part of a cluster.
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D) the galaxy is moving towards Earth.
E) there must be another galaxy nearby.
An observer on a planet sees a spaceship approaching at 0.5c. A beam of light projected
by the ship would be measured by this observer to travel at
A) 0.25c.
B) 0.5c.
C) c.
D) 1.5c.
E) 2.5c.
The expansion rate of the universe is
A) increasing.
B) decreasing.
C) constant.
D) different in different directions.
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E) independent of time.
Why does Saturn radiate even more excess heat than Jupiter?
A) Only Saturn is still radiating heat left over from its formation.
B) Saturn's thick clouds give it a stronger greenhouse effect.
C) Helium rain falling inward generates heat as it descends.
D) Saturn's atmosphere contains much methane, which is very flammable.
E) Saturn is more massive than Jupiter, so its gravitational compression is stronger.
Which statement about gamma ray bursters is not correct?
A) They seem to be coming from far beyond our own Milky Way.
B) They are scaled up X-ray bursters, with more massive objects involved.
C) In seconds, they radiate enormous amounts of energy.
D) Millisecond flickering implies they are tiny in size.
E) The beams may be bi-polar ejections from the hypernova formation of black holes.
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The most tightly wound spiral arms belong to Hubble's type Sa.
What is true of Titan's atmosphere?
A) It is similar to Earth's in composition and density.
B) It is primarily hydrogen.
C) It is oxygen rich.
D) It was discovered by the Voyager 1 spacecraft.
E) It has produced a runaway greenhouse effect.
The mare on Ganymede were formed by
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A) basalt erupting onto the surface.
B) plate tectonics.
C) gravitational interactions with Callisto and Europa.
D) water erupting and spreading over the surface.
E) sulfur spewed from volcanoes.
The observed spectral lines of a star are all shifted towards the red end of the spectrum.
Which statement is true?
A) This is an example of the photoelectric effect.
B) This is an example of the Doppler effect.
C) The second law of Kirchhoff explains this.
D) The star is not rotating.
E) The star has a radial velocity towards us.
As a 6 solar-mass star leaves the main sequence on its way to becoming a red
supergiant, its luminosity
A) decreases.
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B) first decreases, then increases.
C) increases.
D) remains roughly constant.
E) first increases, then decreases.
Why didn't elements heavier than helium form in the first minutes of creation?
A) The first generation of stars used them up too quickly to observe them.
B) There was not enough matter in the universe at that time.
C) When He-4 was formed, the expansion cooled the cosmos below 100 million K.
D) The electrons slowed down enough to be captured into orbits by protons.
E) Only Type I supernovae can produce iron and heavier elements.
All RR Lyrae stars have about the same
A) period of six days.
B) distance of 32 light years.
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C) galactic location and speed.
D) luminosity of about 100 Suns.
E) locations in the centers of globular star clusters.
What problem do refractor telescopes have that reflectors don't?
A) diffraction limited resolution
B) light loss from secondary elements
C) chromatic aberration
D) atmospheric blurring
E) bad seeing
What is true about the stellar populations in the Galaxy?
A) Only old stars are found in the halo.
B) The main star forming regions are outside the Galactic plane.
C) The bluest stars are in the halo.
D) Red stars are only found in the bulge.
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E) Most open clusters are in the halo.
The most important advantage of CCDs over film is that
A) they record much more light in a given exposure time.
B) their images do not have to be developed as film does.
C) they record colors better than film can.
D) they can cover larger areas of the sky than film can.
E) their images never fade, as film can.
Seismic waves are most useful for mapping
A) the surface of Venus with Magellan.
B) the surface of Mars with Global Surveyor.
C) the Earth's core and mantle.
D) the density of the hydrosphere.
E) the depths of the oceans.
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Essentially, the Great Red Spot is
A) Neptune's largest atmospheric feature.
B) a large cyclonic storm (hurricane).
C) always located within 10 degrees of Jupiter's north pole.
D) composed primarily of iron oxide.
E) traveling north and south across Jupiter's face.
The average rate of erosion on the Moon is far less than on Earth because
A) the crust of the Moon is much denser than the Earth's crust.
B) the Moon is much younger than the Earth.
C) the Moon lacks wind, water, and an atmosphere.
D) the Moon's magnetic field protects it from the solar wind better than ours does.
E) the Moon's mare long ago dried up, so there is no more wave erosion there.
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What is the average molecular speed of hydrogen (mass = 1) on Earth (temperature =
300 K)?
A) 4.71 km/s
B) 2.72 m/s
C) 4.71 m/s
D) 2.72 km/s
E) None of the above
Sunspots are dark splotches on the Sun. Which statement is true?
A) They are hotter than the surrounding areas of the Sun.
B) They are extremely cold objects, as cold as Pluto.
C) They are extremely hot, but cooler than the surrounding areas of the Sun.
D) They are solid bodies floating on the surface of the Sun.
E) They are associated with areas of very low magnetic fields.
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The average temperature of the typical dark dust cloud is about
A) 0 K.
B) 2.73 K.
C) 100 K.
D) 3,000 K.
E) 6,000 K.
Very little hydrogen is found in the spectrum of a ________ supernova.
The outward pressure in the core of a red giant balances the inward pull of gravity when
A) the electron orbits are compressed so much they are all in contact.
B) the electrons and protons have combined to form neutrons.
C) hydrogen begins fusing into helium.
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D) carbon fuses into heavier elements.
E) iron forms in the inner core.
Not only does the central engine of active galaxies and quasars require a black hole, but
also ________ to provide the radiative energy.
A) globular clusters for food
B) a very strong magnetic field from neutron stars
C) a source of high-energy electrons for synchrotron radiation
D) an accretion disk of infalling matter
E) a high rate of rotation for the black hole
Neutron stars do not have
A) masses greater than 1.4 solar masses.
B) sizes comparable to large cities.
C) strong magnetic fields.
D) large surface gravities, compared to the Sun.
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E) rotation periods comparable to the Sun's.
Charon's orbit
A) lies exactly in Pluto's orbital plane.
B) is highly inclined to Pluto's orbital plane.
C) is perpendicular to Pluto's equator.
D) is retrograde.
E) has not been determined yet.
The Chandrasekhar limit is
A) the upper-mass limit for a white dwarf.
B) the temperature at which hydrogen fusion starts.
C) the temperature at which helium fusion starts.
D) the point at which a planetary nebula forms.
E) the lower-mass limit for a Type II supernova.
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Electromagnetic radiation
A) can only travel in a dense medium.
B) has only the properties of waves.
C) can behave both as a wave and as a particle.
D) is the same as a sound wave.
E) has nothing in common with radio waves.
In the proton-proton cycle, the positron is
A) massless.
B) a spin conservation particle.
C) an anti-electron.
D) the chief means energy reaches the photosphere.
E) intermediate between the proton and neutron in mass.
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The period-luminosity relation is critical in finding distances with
A) RR Lyrae stars.
B) trigonometric parallaxes.
C) spectroscopic parallaxes.
D) Cepheid variables.
E) pulsars.
Which three worlds have almost identical densities?
A) Mercury, Venus, and Earth
B) Mercury, Mars, and our Moon
C) Deimos, Phobos, and our Moon
D) Earth, Moon, and Mars
E) Mercury, Earth, and Mars
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Which moon of Saturn shows the largest impact crater, relative to its size?
A) Titan
B) Callisto
C) Mimas
D) Miranda
E) Enceladus
Type II supernovae occur when their cores start making
A) carbon.
B) oxygen.
C) silicon.
D) iron.
E) uranium.
Most of the galaxies in the Local Group are
A) big spirals like our Galaxy and M31.
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B) small spirals like M33 and the LMC.
C) small irregulars like the Magellanic Clouds.
D) active galaxies like Centaurus A.
E) small ellipticals like the companions to M31 in Andromeda.
Clusters appear to have ________ dark matter than their individual galaxies.
Why is it hard to observe the chromosphere?
The oblateness of the jovian planets' disks refers to their ________ equatorial
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diameters, compared to the polar diameters.
The Crab Nebula is an example of a ________.
The orbit of Triton is ________, very different from all other major moons.
The oldest rocks found on the Earth's surface date back about ________ billion years.
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Knowing the peak emission wavelength of a blackbody allows you to determine its
________.
On what basis are we sure that no quasar is lurking among the thousands of member
galaxies in the Virgo Cluster, 18 Mpc distant?
Because of their low surface gravities, the Moon and Mercury lack ________.
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Contrast the Oort cloud and the Kuiper belt as possible origins for comets.
The bending of distant starlight by a closer object, resulting in a temporary brightening
of the star, is called ________.
Why are Moon rocks older than Earth rocks, if the impact theory has the Moon being
made by another body striking the newly formed Earth?
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Why are different spectral lines, such as helium, more visible in the corona than in the
Sun's normal absorption spectrum?
How can some mergers activate spirals, and others destroy them?
Hubble divided the spiral galaxies up in what six subtypes?
The process where some fraction of the quasar's enormous energy output is absorbed by
the surrounding galactic gas is called ________.

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