Astronomy Exam 2 Review HSU – Flashcards
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A Particular galaxy has a nuclear region of more or less uniform brightness...
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Spiral
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An Astronomer studying a distant cluster of galaxies finds that several of the 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 deteched
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Double radio sources, quasars, and BL Laceratae objects...
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we view them at different angles to the line of double jets
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Faint Star like objects producing intense radio energy that eventually were called quasars
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an extreme redshift of emission lines that indicated high recessional velocities
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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
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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 the 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 brightest quasar, 3C 273, is estimated to be
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2 billion light years away
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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 an Einstein ring?
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An example of the image formed by a gravitational lens
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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
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What is the galactic halo?
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A spherical distribution of stars and globular clusters centered on the nuclear bulge
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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 distrubution of brightness and a round shape?
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E0
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What name is given to the galaxy with a smooth distrubution of brighness 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
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Who developed the classification system that divides galaxies into spiral, elliptical , and irregular and classifies spirals by the size...
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Edwin Hubble
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A Type II supernova is
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The explosion of a massive star after silicon burning has produces a core of iron nuclei
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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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A white dwarf is
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a small, very hot, low-mass 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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Black holes are named because
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no light or any other electromagnetic radiation can escape from inside them
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During which phase of a low-mass star's life does helium shell burning occur
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Asymptotic gaint branch
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Helium nuclear reactions (helium burning) produces primarily
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carbon and oxygen
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Our sun will end its life by becoming
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a white dwarf
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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 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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The Length of a star's main sequence life is determined by the stars
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spectral type
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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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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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The words "Schwarzschild radius" refer to
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the distance from the center of a black hole to the point at which the escape velocity becomes equal to the speed of light
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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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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 name is given to a non-rotating black hole?
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A Schwarzschild black hole
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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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Which force induced the core to condense and collapse in massive stars at the conclusion of each episode...
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Gravity
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Which nuclear fusion cycle follows the helium fusion phase...
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Carbon "burning"
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Which of the following objects is NOT an end-point of a stars evolutionary life
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Red Giant
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Which of the following stars is most dense
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White Dwarf
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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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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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Ejects its outer layers and become a white dwarf
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A particular 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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500,00 solar masses
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After hydrogen burning ends in a star's core, its position on the H-R diagram moves in a direction towards 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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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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Process of combining nucleu
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Fusion
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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 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 Helium
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What is the relationship between the mass of the protostar and the time needed for it to reach the main sequence...
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More massive protostars reach the main sequence in a shorter time than less massive protostars
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Around which planet does the satellite Titan orbit
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Saturn
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How was Neptune discovered
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By a careful application of Newton's laws to the somewhat irregular motions of Uranus
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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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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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Phobus ans Deimos are moons of which planet
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Mars
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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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The four giant moons of Jupiter were discovered by
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Galileo
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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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The highest daytime temperature reached on the surface of Mercury is
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430 Degrees C, high enough to melt lead and tin
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The reddish color of Mars is probably due to
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Iron oxides sich as rust
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Tomorrow's weather report for Venus would be
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overcast and very hot
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Triton is a satellite of
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Neptune
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Venus
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has no magnetic field
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What characteristic features are seen on the visible surface of Jupiter
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Light bands of cloud separated by dark regions parallel to the equator
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What is the Giant Red Spot
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A large and long-lived, possibly permanent, storm on Jupiter
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What is the composition of Saturn rings
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Water ice or ice-coated rock
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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 is the hottest planet in the solar system, measured at the surface
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Venus
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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 of the following feature have NOT been seen or detected on Mars
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Active volcanoes
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Which of the following planets has no moon
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Venus
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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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"A planet with solid, cratered surface which is alternately very hot and very cold, and having no atmosphere"
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Mercury
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A is a comet that passes extremely close to the sun at perihelion sometimes within a few thousand kilometers of the suns surface
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sun grazing comet
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A meteoroid is the name used to describe a solid partical that
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is drifting around in space
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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
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meteorite
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A shooting star is
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A small particle of interplanetary dust, burning up and glowing
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An asteriod is
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a planetesimal moving in an orbit around the Sun
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Asteroids trapped in one of the Lagrangian points of Jupiter are called Apollo-Amorn objects
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False
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Asteroids whoch orbit the Sun at the same distance as Jupiter are known as
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Trojans
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Asteroids whose orbits carry them across the Earths orbit are known as
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Apollo asteroids
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Comet tails are the result of
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melting and evaporation of its ices
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Jupiter was probably influential in preventing the formation of a planet at the present location of the asteroid belt
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True
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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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The asteroid belt is believed by most astronomers to be composed of
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the remnants of a gaseous planet, disrupted by a massive impact
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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
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The first great comet of the 21st century was Comet
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Comet McNaught
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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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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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The number of times that a typical comet can pass close to the Sun
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100
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The particular feature of a comet that exhibits the most stucture and always points away from the sun
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its ion or gas tail
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THe tail og a comet always points toward the sun
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False
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___ is the only dwarf planet located in the main asteroid belt
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Ceres
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____ is the largest dwarf planet by mass
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Eris
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Energy is transported from the center of the sun to the surface by
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Mostly radiation;
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HOw does the Sun's overall magnetic field behave?
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The Northern and Southern hemispheres have oppisite magnetic polarity, and this reverses every year
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Sunspots are areas on the sun that are
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Cooler than their surroundings
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Sunspots thoughts are caused by
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Differential rotation and its effect on week by minute fieldsDifferential rotation and its effect on week by minute fields just under the Solar surface
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The suns energy is generated by
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Nuclear fusion
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The _____ is then given by the sum of the number have individual sunspots and 10 times the number of groups
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Sunspot number
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The brighter cells surrounded by dark, Narrow boundaries made up the cellular pattern that completely covers the visible surface of the sun they're called
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granules
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The rotation of the sun is
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Fastest at the equator, slower at the mid-latitudes, and the slowest near the poles
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The temperature of the suns photosphere is
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5800 K
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Two forces producing hydrostatic equilibrium in the sun
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Nuclear forces and gravity
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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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What is a spicule on the sun
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A jet of rising gas in the chromosphere
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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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What is the name of the sudden eruptive surge on the surface of the sun
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A flare
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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 disc of the Sun during a total Solar eclipse
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The chromosphere
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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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What is the solar wind
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The suns outer atmosphere streaming out into space
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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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What 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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____ are regions of higher temperature and density surrounding sunspots
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Plages
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The _____ is the sun's outer atmosphere it is visible daring total eclipse is of the sun as a pearly white crown surrounding the sun
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Corona
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A star in the lower left part of the h-r diagram, compared to a star in the middle of the diagram is
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Smaller
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Which of the following atomic or molecular constituents Will exhibit strong absorption lines in Spectra from stars with very high surface temperature
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He II
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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, 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
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Brown dwarf
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I was stage of it 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 the star is very low, which of the following atomic or molecular constituents Will produce the most prominent absorption lines and 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 and find its apparent magnitude to determine its absolute magnitude if you need to know the stars
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Distance
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The H-R 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 is it spectrum
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G2
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The absolute magnitude of the 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 surface can be determined
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By solar spectroscopy
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The most likely places whereIn the stars and planetary systems performing in the universe are
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In the 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
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It is cooler than the sun
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The service 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 White dwarf Star
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A star of about the same size 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 I observed through a set of photometric filters, the brightness of a distant star is seen to be bright through the ultraviolet filter, less bright through the blue filter, and faintest studio filter
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This star has a very high surface temperature
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Where are the most massive stars be found in the main sequence
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The upper left end
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Where on the H-R diagram do most local stars in our universe congregate
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On the main sequence
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Which important stellar parameter can be determined by observations of binary stars
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Stellar mass
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Which of the following for spectral classifications represents the coolest stellar surface temperature
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G4
