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Flashcards

ASTRON 103 MIDTERM 1

HARPER PLOECKELMAN Astronomy English 48 cards

Cards in this deck (48)

  1. 1Right Ascension0hrs to 24hrs
  2. 2declination0-90 degrees (+/-)
  3. 3eclipticpath sun takes throughout the sky in one year
  4. 4zenithline directly up
  5. 5meridiandivision of sky into East and West halves
    (objects rise in the East and set in the West)
  6. 6horizonaltitude= 0 degrees
  7. 7speed of lightc=3.00 x 10^8 m/s
  8. 8wavelengthλ, the distance between successive crests in an electromagnetic wave
  9. 9frequencyf, number of waves crests that pass a given point in one period of time. measured in Hz
  10. 10Energy of photonsEphoton= hf
    h=6.626x10-34 J s
  11. 11red lightlong wavelengths, low frequency
  12. 12violet lightshort wavelengths, high frequency
  13. 13nucleus10^-15meters in size
    made of protons, neutrons, and electrons
  14. 14protonspositively charged
  15. 15nuetronsno charge
  16. 16electronsnegative charge
  17. 17absorption lineselectron absorbs photon and moves into higher orbital
    absorption lines have specific dips (dark lines on spectra)
  18. 18emission spectrumelectron moves from a higher to a lower orbital & emits a photon
    emission lines spike (bright lines on spectra)
  19. 19electron volts3.03x10^-19 Joules
  20. 20diffuse gasatoms are v spread out and barely collide
    atoms only go through emission/absorption at v specific areas
  21. 21dense opaque gasmany collisions (atoms are v packed together)
    light can be shown over an entire area instead of only occuring at v specific areas
  22. 22temperaturehow fast atoms in a medium are moving
    low temp= relatively slow movement
    high temp= fast, chaotic movement
  23. 23KelvinT(K)= 273.15 + T(Celsius)
  24. 24Wein's LawHotter bodies emit more strongly at shorter wavelengths (peak wavelength is proportional to temp)
    T=2.9x10^6K nm/ λmax
  25. 25Stefan-Boltzmann LawTotal light output of a body increases with temp. A hotter object will emit more radiation than a cold object @ EVERY wavelength
    linked to energy flux
  26. 26energy fluxenergy emitted per square meter at a body's surface (units are Watts/m^2)
    F= σT4
    σ= 5.7×10-8 Watts/(m2 K4)
  27. 27luminositytotal energy output per second
    can be calculated if we know size
    σT4 x stars surface area = σT4 x 4πr2
  28. 283 kinds of spectra1. Continuous
    2. Emission Line
    3. Absorption Line
  29. 29Continuous SpectraHot dense gas.
    a complete rainbow of colors with smooth distribution of intensity
  30. 30emission line spectrahot diffuse gas
    Atoms emit only at discreet wavelengths as excited electrons transition to lower energy levels that depend on its composition and temperature, producing a spectrum with bright emission lines
  31. 31absorption line spectraa cool diffuse gas in front of a source
    Light is absorbed at discreet wavelengths as electrons in the gas are excited to higher energy levels by background photons
    Leaves dark absorption lines on spectrum
    Collisions are rare in cool gas, so most electrons are in low energy states
  32. 32redshiftmoving away
    longer wavelength
  33. 33blueshiftmoving towards
    shorter wavelength
  34. 34radial velocitythe velocity directly along our line of sight
    - coming TOWARDS observer
    + moving AWAY from observer
  35. 35measuring shiftVrad/c = (λshift- λrsest)/ λrest
    Vrad= radial velocity
  36. 362 ways telescope bring light to focus1. Refraction
    2. Reflection
  37. 37Refractionchange of direction of light when it passes through one medium to another (do not perfectly cancel each other out)
  38. 38Cons of Refraction Telescopes- V dif to build (glass is heavy, it can only be supported on the edges, has to be entirely perfect or light wont focus)
    -lens has to be at end of telescope which makes it v hard to steer
  39. 39Reflectionlight bounces off a curved surface
  40. 40Pros of Reflection TelescopesCurved Mirrors: Can be large and supported from behind, only the surface has to be perfect
    Design Flexibility: lens doesnt have to be at end, which allows for more compact sizes
    Coatings: dif coatings allow dif frequencies of light to pass through
    Segmented Mirrors: hexagonal mirrors allow for precise assembly and individual Maintenace
  41. 41ways telescopes and electronic light detectors aid our eyes1. light gathering power (bigger telescopes collect more photons which approve our ability to see faint objects)
    2. resolving power (ability to reveal fine detail)
    3. magnification (makes an object larger)
    4. sensitivity (ability to collect light at wavelengths the human eye cant see)
  42. 42telescope aperturediameter of main optical element
    Larger apertures allow more photons to be collected per unit time, making it more efficient to take pictures of dim object
    D= Light gathering power = collecting area = π D^2 / 4
  43. 43diffractioncauses image to be blurry bc it causes light from a specific point to be spread out more
  44. 44resolutioncharacterized by measuring the SMALLEST angular separation 2 pts of light can have and still appear well separated
    Theta = 2.5x10^5 (wavelength/ D)
    *high res, theta is small.
    low res, theta is big*
  45. 45seeingthe angular size of a star blurred by the atmosphere
    when the atmosphere is stable, we say the seeing is good
  46. 46photographic film~1850 we started using film that allowed us to collect photons for several hours onto an image
    film is only sensitive to ~1-2% of incoming photons (like human eye)
  47. 47Charge Coupled Device (CCD)Made up of pixels
    ~100x more sensitive than the human eye (captures ~95-98% of incoming photons)
  48. 48Pixelssemiconductive material divided into square regions

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Astronomy Flashcards on ASTRON 103 MIDTERM 1, created by HARPER PLOECKELMAN on 01/10/2024.
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