Astronomy Chapter 8 Flashcards
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Questions and Answers

What is a star?

  • A cold lump of rock
  • A glowing ball of gas held together by its own gravity (correct)
  • A planet that reflects sunlight
  • A type of comet

    • What is the Sun's radius?

    700,000 km

    What is the Sun's mass?

    2 x 10^30 kg

    How is solar rotation measured?

    <p>Timing sunspots as they travel across the solar disk</p> Signup and view all the answers

    How long does it take the Sun to rotate?

    <p>A month</p> Signup and view all the answers

    The Sun spins at the same speed at the equator and the poles.

    <p>False</p> Signup and view all the answers

    How is the Sun's temperature measured?

    <p>Analyzing the observed solar spectrum</p> Signup and view all the answers

    What is the Sun's temperature?

    <p>5800 K</p> Signup and view all the answers

    What is the photosphere?

    <p>The visible surface of the Sun</p> Signup and view all the answers

    What is the thickness of the photosphere?

    <p>Very thin, 500 km</p> Signup and view all the answers

    What is the Sun's core?

    <p>The site of powerful nuclear reactions</p> Signup and view all the answers

    What is the chromosphere?

    <p>The Sun's lower atmosphere</p> Signup and view all the answers

    What is the corona?

    <p>The tenuous outer atmosphere of the Sun</p> Signup and view all the answers

    What is solar wind?

    <p>An outward flow of fast-moving charged particles</p> Signup and view all the answers

    What is the radiation zone?

    <p>Region of the Sun's interior with high temperatures</p> Signup and view all the answers

    What is the convection zone?

    <p>Region of constant convection motion below the surface</p> Signup and view all the answers

    Where do ions form in the Sun?

    <p>In the convection zone</p> Signup and view all the answers

    What is the most important property of the Sun?

    <p>Its light</p> Signup and view all the answers

    What is luminosity?

    <p>Total energy radiated by a star each second</p> Signup and view all the answers

    What is the Sun's core temperature?

    <p>10 million K</p> Signup and view all the answers

    What is the standard solar model?

    <p>A consistent picture of the Sun developed through computational means</p> Signup and view all the answers

    The Sun's bulk properties vary significantly from day to day.

    <p>False</p> Signup and view all the answers

    What is hydrostatic equilibrium?

    <p>Condition in which gravity's inward pull is balanced by internal pressure</p> Signup and view all the answers

    Why doesn't the Sun's surface vibrate?

    <p>Due to internal pressure waves reflecting off the photosphere</p> Signup and view all the answers

    What is helioseismology?

    <p>The study of conditions below the Sun's surface</p> Signup and view all the answers

    Where is the Sun's density high?

    <p>In the core</p> Signup and view all the answers

    Where is 90% of the Sun's mass contained?

    <p>The inner half of its radius</p> Signup and view all the answers

    How does energy produced in the Sun's core travel outward?

    <p>In the form of radiation</p> Signup and view all the answers

    Do photons reach the surface of the Sun?

    <p>False</p> Signup and view all the answers

    What is sunlight?

    <p>A form of visible energy</p> Signup and view all the answers

    How does escaped energy reach the Sun's surface?

    <p>Through convection</p> Signup and view all the answers

    Hot solar gas moves _____ while cooler gas above it _____

    <p>outward, sinks</p> Signup and view all the answers

    What is meant by the hierarchy of convection cells?

    <p>There are organized structures of convection cells</p> Signup and view all the answers

    What does the deepest tier of convection cells contain?

    <p>Large cells tens of thousands of kilometers in diameter</p> Signup and view all the answers

    Convection proceeds in the solar atmosphere.

    <p>False</p> Signup and view all the answers

    What is granulation?

    <p>Mottled appearance of the solar surface</p> Signup and view all the answers

    Study Notes

    The Sun: Key Facts

    • A star is a glowing ball of gas maintained by gravity and powered by nuclear fusion.
    • The Sun has a radius of 700,000 km and a mass of 2 x 10^30 kg.

    Solar Rotation and Structure

    • Solar rotation is timed by the movement of sunspots across the solar disk, taking approximately a month to complete one rotation.
    • The Sun experiences differential rotation, spinning faster at the equator than at the poles.

    Temperature and Atmosphere

    • The Sun's temperature measures 5800 K, determined by analyzing the solar spectrum.
    • The photosphere is the Sun's visible surface, approximately 500 km thick, lying above the interior layers and below the chromosphere.
    • The chromosphere constitutes the Sun's lower atmosphere, while the corona is the tenuous outer atmosphere, extending into the solar wind.

    Solar Energy and Internal Structure

    • The Sun’s core, with a temperature of 10 million K, is where nuclear reactions occur, generating all of its energy.
    • The radiation zone features high temperatures that ensure complete ionization of gas, causing photons to travel easily through this region.
    • The convection zone, extending about 20,000 km below the surface, is where solar material undergoes constant convective motion.

    Characteristics and Dynamics

    • Ions are formed in the convection zone where hot solar gas rises outward while cooler gas sinks.
    • Luminosity represents the total energy radiated by the Sun per second across all wavelengths, seen as its crucial property of light.
    • Hydrostatic equilibrium in the Sun occurs when gravity’s inward pull is balanced by pressure forces.

    Helioseismology and Structure

    • The Sun's surface stability results from internal pressure waves that reflect off the photosphere and traverse the solar interior.
    • Helioseismology studies the internal conditions of the Sun by analyzing sound waves crossing through its interior.

    Density and Mass Distribution

    • The Sun's highest density is found in its core, with 90% of its mass contained within the inner half of its radius.
    • Energy produced in the core travels outward as radiation, while convection processes occur to transport escaped energy to the surface.

    Surface Characteristics

    • Sunlight manifests as visible energy, produced by convection which does not extend into the solar atmosphere due to insufficient gas.
    • Granulation describes the mottled appearance of the solar surface, resulting from the interaction of rising hot material and sinking cooler material within convection cells just beneath the photosphere.

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    Test your knowledge of the Sun with these flashcards from Chapter 8. Each card presents important terms and definitions related to solar characteristics, including its mass, radius, and rotation. Perfect for students studying astronomy.

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