HSU Astronomy Exam 2 – Flashcards
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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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Phobos and 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 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 such 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 composition of Saturn's 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 features 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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Which of the planets fits the following description: "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 comet's tail
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always points away from the sun, regardless of the motion of the comet
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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 Sun's surface.
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sun grazing comet
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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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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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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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An asteroid 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-Amor objects.
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False
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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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Asteroids whose orbits carry them across the Earth's orbit are known as
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Apollo asteriods
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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 exists between the orbits of the planets
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Mars and Jupiter
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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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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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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 (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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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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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 trail
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The tail of 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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Comet tails are the result of
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melting and evaporation of ices from the comet core.
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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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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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How does the Sun's overall magnetic field behave?
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The northern and southern hemispheres have opposite magnetic polarity, and the polarity reverses every 11 years.
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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 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 Sun's energy is generated by
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nuclear fusion
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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 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 rotation of the Sun is
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fastest at the equator, slower at mid-latitudes, and slowest near the poles.
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The temperature of the Sun's photosphere is
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5800 K
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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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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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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 a 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 disk 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 Sun's 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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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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__________________ 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 during total eclipses of the Sun as a pearly white crown surrounding the Sun.
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corna
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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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Absorption line strengths are used in the spectral classification of stars and the determination of surface temperatures. 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, 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 red giant?
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a star 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 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 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
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Which important stellar parameter can be best determined by observations of binary stars?
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Stellar mass
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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
