final hsu astronomy 7-13 – Flashcards
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Which planet has wide, bright rings that are easily visible from Earth?
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Saturn
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Where in the solar system would you look for liquid hydrogen?
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In the deep interiors of Jupiter and Saturn.
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What are the characteristic features on the visible surface of Jupiter?
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Light and dark bands of clouds parallel to the equator.
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Where has water ice been found on Mercury?
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In permanently shadowed crater floors at the north and south poles.
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Which of the following features have NOT been seen or detected on Mars?
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Active volcanoes
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The Martian magnetic field is
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weak and localized, not at all like the global magnetic field of Earth.
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Which satellite of Jupiter is volcanically active?
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Io.
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Venus
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has no magnetic field.
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Jupiter has a magnetic field that is
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much more powerful than that of Earth
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Which is the only planet whose surface features can easily be seen through a telescope from Earth?
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Mars
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Which planet has its rotation axis tilted at 98 degrees from the vertical to its orbit?
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Uranus.
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What are the characteristics of the magnetic field of Uranus?
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It is tilted almost 60 degrees to the axis of planetary rotation and is offset from the planet's center
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What is the composition of Saturn's rings?
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Water ice or ice-coated rock.
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Which is the hottest planet in the solar system, measured at the surface?
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Venus
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Saturn's moon, Titan, is different from all other moons of planets because
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it possesses a thick atmosphere.
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Which of the following planets has no moon?
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Venus
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Which is the least dense planet in the solar system?
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Saturn
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The four major moons of Jupiter are collectively named after which early astronomer?
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Galileo
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Which is the biggest planet in the solar system?
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Jupiter
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Neptune's high cirrus clouds consist of
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methane ice crystals
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On which planet can we see prominent but variable ice caps?
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Mars
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On which planetary body can distinct evidence be seen for the flow of water at an earlier time?
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Mars.
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On which planet is the Great Red Spot found?
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Jupiter
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What is the major constituent of the atmosphere of Mars?
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CO2 (carbon dioxide).
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The geology and geography of the surface of the Venus is best described as
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mostly volcanic plains, with two continent-sized uplands, and a number of large volcanoes.
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Which of the Moons of Jupiter is characterized by an exceptionally smooth, icy surface, few craters, and many streaks and cracks?
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Europa.
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Which of the following physical properties of Venus are very similar in value to those of Earth?
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Mass and radius and hence average density and surface gravity.
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Tomorrow's weather report for Venus would be
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overcast and very hot.
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What is the Great Red Spot?
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A large and long-lived, possibly permanent, storm on Jupiter
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Which of the following planets rotates on its axis in a retrograde fashion, opposite to that of most of the planets and opposite to the direction of revolution of the planets?
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Venus
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The inner planets, in order of increasing planetary radius, are
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Mercury, Mars, Venus, Earth
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Which of the planets fits the following description: "A cool, solid surface, with a thin CO2 atmosphere and occasional dust clouds"?
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Mars
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Which of the following properties do the terrestrial planets, Mercury, Venus, Earth and Mars, have in common?
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They all have solid surfaces
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Olympus Mons is
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a volcano on Mars.
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The reddish color of Mars is probably due to
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iron oxides such as rust.
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What are the Valles Marineris?
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A large rift valley system associated with the great volcanoes on Mars.
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The Kirkwood gaps are caused by
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the gravitational pull of Jupiter, which nudges asteroids into new orbits.
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Comet tails are the result of
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melting and evaporation of ices from the comet core.
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The orbits of comets are
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randomly oriented in the solar system and can extend far beyond the orbit of Pluto.
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What is the difference between a long-period comet and a short-period comet?
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Long-period comets orbit in the Oort cloud, whereas short-period comets orbit in the Kuiper belt.
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Asteroids whose orbits carry them across the Earth's orbit are known as
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Apollo asteroids.
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A shooting star is
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a small particle of interplanetary dust, burning up and glowing as it enters the Earth's atmosphere.
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The asteroid belt is believed by most astronomers to be composed of
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rocky debris left over from the formation of the solar system.
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Which solar system object was found on January 1, 1801, located between the orbits of Mars and Jupiter?
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The dwarf planet Ceres
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The cause of the "meteor showers," seen at regular times each year upon Earth, is most probably
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the Earth moving through the remnant dust and rock fragments of an old comet which are orbiting the Sun in the comet's old orbit.
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Asteroids which orbit the Sun at the same distance as Jupiter are known as
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Trojans
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Which of the following is not a dwarf planet?
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Neptune
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The ionized gas tail of a comet is always aligned
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in the comet-Sun line.
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The most common meteorites to hit the Earth are
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the stony meteorites.
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An asteroid is
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a planetesimal moving in an orbit around the Sun.
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A meteoroid is the name used to describe a solid particle that
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is drifting around in space.
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The nucleus of a typical comet is
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irregular in shape, with a very dark and cratered surface.
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A piece of rock from outer space that reaches the Earth's surface after surviving a fiery passage through the Earth's atmosphere is known as a(n)
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meteorite.
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Which of the following is a moon of Eris?
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Dysnomia
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_________ is the largest dwarf planet
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Eris
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The number of times that a typical comet can pass close to the Sun (i.e., the number of orbits that the comet can complete) before it is completely vaporized or destroyed is about
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100.
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_________ is the only dwarf planet located in the main asteroid belt.
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Ceres
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The particular feature of a comet that exhibits the most structure and always points away from the Sun is
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its ion or gas tail.
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The asteroid belt exists between the orbits of the planets
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Mars and Jupiter
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Why does no major planet orbit the Sun at the location of the asteroid belt?
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Jupiter's gravitational pull stirred up the planetesimals, preventing them from coalescing into a single large object.
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Which of the following statements is NOT true for asteroids?
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Only a minority of all asteroids are in the asteroid belt.
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A star in the lower left part of the Hertzsprung-Russell diagram, compared to a star in the middle of the diagram, is
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smaller
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An astronomer is measuring the brightness of a particular star through a telescope, using different filters in the visual (yellow-green), violet, and ultraviolet regions. What is the name of the technique being used by this astronomer?
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Photometry
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An object which is too massive to be a planet but not massive enough to be a star is called
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A brown dwarf
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At what stage of its evolutionary life is the Sun?
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Main sequence, middle age.
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If a star is 100 light years away, what is its approximate distance in parsecs?
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30 parsec
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If the surface temperature of a star is very low, which of the following atomic or molecular constituents will produce the most prominent absorption lines in its spectrum?
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TiO
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Spectral types of stars (e.g., O, B, A, F, G, K, M) define uniquely their
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surface temperatures.
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Suppose you observe a previously undiscovered star and find its apparent magnitude. To determine its absolute magnitude you need to know the stars
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distance
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The Hertzsprung-Russell diagram is a plot of
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absolute magnitude (or intrinsic brightness) against temperature of a group of stars.
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The Sun's classification in terms of its surface temperature, as determined from absorption lines in its spectrum, is
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G2
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The absolute magnitude of a star is
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equal to the apparent magnitude if the star is 10 parsecs away.
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The chemical makeup of the Sun's surface can be determined
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by solar spectroscopy.
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The most likely places where stars and planetary systems are forming in the universe are
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in nebulae composed of gas and dust.
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The spectral class of the star Enif is K2, while that of the Sun is G2. Which of the following conclusions can be drawn about Enif from this information?
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It is cooler than the Sun.
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The surface temperature of a nearby star can best be determined from spectral classification by examining
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the pattern of spectral absorption lines from various atoms.
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What is a protostar?
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A small interstellar cloud, before it collapses to become a star.
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What is a red giant?
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A star that is burning hydrogen into helium in a shell around the core.
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What is a white dwarf star?
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A star of about the same size (diameter) as the Earth.
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What is the most abundant element in the universe?
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Hydrogen
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When observed through a set of photometric filters, the brightness of a distant star is seen to be brightest through the ultraviolet filter, less bright through the blue filter, and faintest through the yellow filter. What conclusion can be drawn from this information, assuming no absorption of light between the star and Earth?
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The star has a very high surface temperature.
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Where are the most massive stars to be found in the main sequence of a Hertzsprung-Russell diagram?
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The upper, left end.
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Where on the Hertzsprung-Russell diagram do most local stars in our Universe congregate?
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On the main sequence, where stars are generating energy by fusion reactions.
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Which of the following four spectral classifications represents the coolest stellar surface temperature?
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G4
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Which important stellar parameter can be best determined by observations of binary stars?
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Steller Mass
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The temperature of the Sun's photosphere is
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5800 K
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Granulation on the surface of the Sun is caused by
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convective currents carrying heat from beneath the surface.
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Sunspots are caused by
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differential rotation and its effect on weak magnetic fields just under the solar surface.
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The layer of the sun that is normally visible to us is the
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photosphere
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The surface of the Sun is divided into light-colored areas with dark boundaries in a cellular pattern. What are these cells called?
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Granules
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What process provides the power for the Sun?
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The fusion of hydrogen into helium.
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The brighter cells surrounded by dark, narrow boundaries making up the cellular pattern that completely covers the visible surface of the Sun are called
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granules
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The ______ is the Sun's outer atmosphere. It is visible during total eclipses of the Sun as a pearly white crown surrounding the Sun.
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corona.
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What is the average length of time from one maximum in the number of sunspots on the Sun to the next maximum?
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11 years.
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The ____________ is then given by the sum of the number of individual sunspots and ten times the number of groups.
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sunspot number
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The two forces producing hydrostatic equilibrium in the sun are
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nuclear forces and gravity.
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Thermonuclear fusion reactions in the core of the Sun convert four hydrogen atoms into one helium atom. The helium atom has
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less mass than the four hydrogen atoms, because the energy produced is lost from the atom, and energy is equivalent to mass by E = mc2.
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What is the solar wind?
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The Sun's outer atmosphere streaming out into space.
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What is the photosphere of the Sun?
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The visible "surface" of the Sun.
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________ are regions of higher temperature and density surrounding sunspots.
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Plages.
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What is the name of the layer of the Sun's atmosphere that appears as a pinkish ring just outside the visible disk of the Sun during a total solar eclipse?
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The chromosphere
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Sunspots are
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cooler, darker regions on the Sun's surface.
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The Sun's energy is generated by
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nuclear fusion
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The thickness of the photosphere, or the visible "surface" of the Sun, is
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about 400 km.
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Where is the chromosphere on the Sun?
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It is the layer above the visible surface of the Sun.
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Where is the coolest region in the Sun?
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In the photosphere.
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Energy is transported from the center of the Sun to the surface by
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mostly radiation; convection only in the outer layers
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Sunspots are areas on the sun that are
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cooler than their surroundings.
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What is the name of a sudden eruptive surge on the surface of the Sun?
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A flare
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What are the names of the three layers in the Sun's atmosphere, in order from highest to lowest?
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Corona, chromosphere, photosphere
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A particular giant molecular cloud in interstellar space has a mass of 2,000,000 solar masses. What is the mass of helium in this cloud?
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500,000 solar masses.
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After hydrogen burning ends in a star's core, its position on the Hertzsprung-Russell diagram moves in a direction toward the
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upper right
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At what point in its evolution will a protostar stop shrinking and stabilize into a star?
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When nuclear processes generate enough energy and internal pressure to resist gravitational contraction.
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For any star on the main sequence, the same star when it was a protostar was
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larger and cooler
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How does the temperature of an interstellar cloud affect its ability to form stars?
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Higher temperatures inhibit star formation.
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Hydrogen in molecular form, H2, is thought to be very abundant in gas clouds in space, but these molecules emit radiation relatively inefficiently, since they are symmetrical molecules. Which other molecule occurs in close association with H2 and is used as a probe for molecular clouds?
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CO
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In which part of the electromagnetic spectrum are molecules most easily detected?
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Radio waves
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New stars are formed from
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huge, cool dust and gas clouds
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Objects that are intermediate between stars and planets.
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Brown dwarf
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Star formation takes place in
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giant molecular clouds
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The Jeans instability describes
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the overcoming of gas pressure by self-gravity within a cold and dense interstellar cloud to form a star.
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The __________________ is the "mountain" in the potential energy that must be crossed over to move the two nuclei close enough together to fuse.
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Coulomb barrier
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The energy released in a thermonuclear reaction comes from the conversion of matter into energy according to ____________ equation.
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Einstein's
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The evolutionary tracks of stars during the formation process.
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Hayashi Tracks
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The lowest mass that a protostar can have and still become a star (i.e., start thermonuclear reactions in its core) is
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slightly less than 1/10 of a solar mass
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The major part of a star's life is spent on the:
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Main Sequence
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The space between stars is known to contain
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gas, both atomic and molecular, and dust.
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What do our atmosphere and a reflection nebula surrounding a star have in common?
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They both appear blue because of preferred scattering of this color of light.
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What fraction of the mass of a typical interstellar cloud is hydrogen?
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74%
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What is believed to be the maximum mass that a star can have?
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About 100 solar masses.
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______________ is the process of splitting atoms and powers atomic bombs and nuclear power reactors.
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Fission
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While a star is on the main sequence, its energy comes primarily from
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nuclear fusion
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Which are the two most abundant elements in the universe?
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Hydrogen and Hellium
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What is the relationship between the mass of a protostar and the time needed for it to reach the main sequence, after it forms inside an interstellar cloud?
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More massive protostars reach the main sequence in a shorter time than less massive protostars.
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Which force induces the core to condense and collapse in massive stars at the conclusion of each episode of nuclear fusion, such as the carbon, oxygen and silicon fusion cycles?
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Gravity
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Our Sun will end its life by becoming
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a white dwarf.
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Black holes are so named because
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no light or any other electromagnetic radiation can escape from inside them
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What name is given to a non-rotating black hole?
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A Schwarzschild black hole.
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A planetary nebula is
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an expanding gas shell surrounding a hot white dwarf star.
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Which type of main-sequence stars live the longest?
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M
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A black hole can be thought of as
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strongly curved space.
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A Type II supernova is
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the explosion of a massive star after silicon burning has produced a core of iron nuclei.
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The endpoint for the evolution of a low mass star is ________________.
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white dwarf
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The lenght of a star's main sequence life is determined by the star's
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spectral type
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What name is given to a rotating black hole?
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A Kerr black hole.
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The stars which eventually become white dwarfs are those which start life with masses less than
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8 solar masses
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Which of the following will a high-mass star (say, 25 times the mass of the Sun) NOT do at or near the end of its life?
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Eject its outer layers and become a white dwarf.
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During which phase of a low-mass star's life does helium shell burning occur?
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Asymptotic giant branch.
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Which nuclear fusion cycle follows the helium fusion phase as a massive star evolves?
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Carbon "burning."
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Which of the following objects is NOT an end-point of a star's evolutionary life?
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Red giant
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The final remnant of the evolution of a red giant star that has ejected a planetary nebula is
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a white dwarf star
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A white dwarf star is about the same size as
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the Earth
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The main product of silicon fusion reactions in the core of a massive star is
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iron.
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What is the event horizon of a black hole?
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The "surface" from inside of which nothing can escape
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What is the escape velocity from inside a black hole?
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Greater than the speed of light.
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Which of the follwoing stars is most dense?
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White Dwarf
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Helium nuclear reactions (helium burning) produces primarily
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carbon and oxygen
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A white dwarf is
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a small, very hot, low-mass star.
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Which of the following statements is NOT a property of neutron stars?
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They contain strong gravitational fields but weak magnetic fields
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A particular galaxy has a nuclear region of more or less uniform brightness from which long lanes of stars curve outward. What type of galaxy is this?
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Spiral
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An astronomer studying a distant cluster of galaxies finds that several of the galaxies are spiral-shaped, with a large nuclear region and tightly wound arms. How should the astronomer classify these galaxies?
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Sa
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Astronomy with a radio telescope was initiated by
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an amateur astronomer Grote Reber, after Jansky had detected radio energy from the galaxy.
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Double radio sources, quasars, and BL Lacertae objects are now considered to be the same basic type of object—an accretion disk producing two oppositely directed jets—but appear to us to be very different because
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we view them at different angles to the line of the double jets. Face-on to the accretion disk the source will look like a BL Lac object, edge-on as double radio sources, and between these positions a quasar.
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Faint star like objects producing intense radio energy that eventually were called quasars were found to have an unusual feature in their optical spectra. This feature was
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an extreme redshift of emission lines that indicated high recessional velocities and hence great distances, requiring extremely high energy output in order to be detected.
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In the "unified model" of active galaxies, the main difference between quasars, BL Lacertae objects, and radio galaxies appears to be that
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we see the accretion disk around the central black hole from a different angle in each case—face-on for BL Lacertae, edge-on for radio galaxies, and in between for quasars.
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In the verification of the Hubble law for the expansion of the universe and the determination of the constant H0, the greatest difficulty has been
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the accurate determination of distances to very distant galaxies.
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One of the first three astronomical objects detected at radio wavelengths by Grote Reber in the late 1930s was
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the galactic center.
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Quasars appear to be
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very distant and intrinsically bright objects moving in random directions at high speeds.
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Seyfert galaxies are
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spiral galaxies with extremely active cores.
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The Hubble law, representing observations of distant objects in the universe, relates which two parameters?
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The mass of a distant object and its recession velocity.
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The Milky Way Galaxy appears to have a spiral structure with
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four separate major arms.
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The distance to the bright quasar, 3C 273, is estimated to be
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2 billion light-years.
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The factor that misled Herschel into concluding that the stars of the Milky Way were distributed with the Sun at the center of the Galaxy was
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interstellar dust, which obscured the more distant stars and thereby localized his observations.
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What is a barred spiral galaxy?
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A galaxy with a bar through the nuclear bulge and the spiral arms starting from the ends of the bar.
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What is the Hubble classification for a spiral galaxy with a small nuclear region and loosely wound arms?
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Sc
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What is the Local Group?
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A cluster of about 30 galaxies of which the Milky Way is a member.
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What is the most outstanding feature of a quasar compared to other objects in deep space?
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Its enormous output of energy.
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What method is used to determine the distances of very remote galaxies?
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Use of their spectral redshifts and the Hubble law.
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What name is given to a galaxy with a smooth distribution of brightness and a round shape?
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E0.
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What name is given to a galaxy with a smooth distribution of brightness and a very elongated shape?
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E7.
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Where is the Sun located in our galaxy?
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In or close to the Orion arm, which is between the Sagittarius and Perseus arms.
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Who developed the classification system that divides galaxies into spiral, elliptical, and irregular and classifies spirals by the size of their nuclear region and the tightness of winding of their arms?
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Edwin Hubble.
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