CSET 118: Astronomy

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  1. Describe the chemical composition and physical structure of the universe
    • chemical composition shows an abundance of hydrogen, helium, lithium and other "light" elements - key evidence for the Big Bang theory 
    • about 75% of observable universe is hydrogen 
    • 25% is helium atoms
    • other elements in trace amounts 
    • "heavy" elements created in the cores of massive stars 

    • the physical structure of the universe:
    • the observable universe consists of stars and their planetary systems, organized into galaxies 
    • the four fundamental forces are gravitational, electromagnetic, and the strong and weak nuclear forces
    • gravity has shaped the physical structure of the universe 
    • every mass in the universe attracts every other mass
  2. Describe the structure of the solar system and its place in the Milky Way galaxy
    • the solar system is composed of the sun and the bodies orbit around it 
    • the moons or satellites of the planets orbit the planets as that system orbits the sun 
    • the orbits of the planets lie nearly in a plane, as the solar system is disk-shaped
    • the solar system is located near a spur off the perseus spiral arm, about 2/3s away from the center to the edge of the visible disk of the galaxy
  3. Distinguish between stars and planets
    • stars shine by nuclear fusion
    • planets shine by reflected light 
    • brown dwarfs are neither planets nor stars - borderline in terms of mass
  4. Recognize that stars vary in color, size, and luminosity
    • a star's mass determines its size, temperature, color and luminosity 
    • stars come in different colors - a star's color comes from its surface temperature 
    • the size of a star is given in terms of its radius, sun is average size 
    • luminosity - energy a star radiates per unit time, function of the star itself and does not depend on distance
  5. Describe a simple model of how fusion in stars produces heavier elements and results in the production of energy, including light
    • fusion occurs in the core of a star, where the pressure and temperature are highest - ensures that particles come together with enough energy to overcome the electric forces 
    • fusion reaction in stars is called proton-proton chain where four hydrogen nuclei form one helium nucleus plus the release of energy 
    • mass of helium nucleus is slightly less than the 4 initial protons - difference in mass is from the energy that is carried off by nuetrinos and gamma rays which is shown by E=mc2

  6. Describe the regular and predictable patterns of stars and planets in time and location
    • most objects in the night sky move in predictable patterns due to Earth's spin about its axis and its orbit around the Sun 
    • the stars and planets rise in the east and set in the west, as does the Sun due to Earth's spin about its axis 
    • the sun rises due east and sets due west only around the spring and fall equinoxes
  7. Explain and predict changes in the moon’s appearance (phases)
    • the moon cycles through phases over a period of 28 days caused by changing solar illumination 
    • new - moon rises during the day approximately at the same time as the sun, making the moon difficult to see 
    • first quarter - crescent shines by sunshine and rest of the moon shines from the earth, rises at noon  
    • full moon - rises at sunset, visible face of the moon facing earth is fully illuminated, sun is on the other side of earth
    • last quarter - the visible face of the moon is only half illuminated, rises at midnight and is high in the sky as the sun rises
  8. Describe the use of astronomical instruments in collecting data, and use astronomical units and light years to describe distances
    • optical telescope - collects light, size of lens - aperture - is important, resolution is measured in arcseconds (angle in the sky)
    • refractors - collect light through a lens
    • reflectors - collect light with a mirror 
    • telescopes for other wavelengths are useful for studying the lifecycles of stars 
    • astronomical unit = the average distance from the sun to the earth 
    • light year = distance traveled by a photon of light in one year

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CSET 118: Astronomy
2013-06-29 20:01:09

Science CSET
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