Chapter 21 study guide.

  1. What is electromagnetic radiation?
  2. Energy from stars that travels through space in the form of different wavelengths
  3. What are the 7 different categories of electromagnetic radiation?
  4. Radio
  5. Microwave
  6. Infrared
  7. Visible light
  8. Ultraviolet
  9. X-ray
  10. Gamma ray
  11. Explain something special about each type of electromagnetic radiation
  12. Radio: Longest wavelength; used for phone, radio and TV communication
  13. Microwave: Longer wavelength used to cook food
  14. Infrared: Can be felt as heat
  15. Visible light: The only kind of electromagnetic radiation we can see
  16. Ultraviolet: Very small amounts can cause bad sunburn
  17. X-ray: Can be used to see bones, the wavelengths are so small
  18. Gamma ray: The most energetic and powerful kind of electromagnetic radiation. Smallest wavelength.
  19. Why do we look at stars through different telescopes that can “see” different types of electromagnetic radiation?
  20. We can learn a lot more about a star by seeing what kind of electromagnetic radiation it produces and how much of the different kinds of electromagnetic radiation it produces
  21. What is the definition of wavelength?
  22. The length between one wave crest and the next wave crest (or trough)
  23. What is the longest wavelength of visible light?
  24. Red
  25. What is the shortest wavelength of visible light?
  26. Violet
  27. What does the Earth have that protects us from most of the harmful types of electromagnetic radiation?
  28. Atmosphere
  29. What are the 3 things astronomers look at to classify stars?
  30. Size
  31. Temperature
  32. Luminosity (brightness)
  33. Because space is so big, scientists use a different kind of measurement to measure distance. What is it?
  34. Light-years
  35. Define the term in # 10
  36. The DISTANCE light travels in one year
  37. What is the difference between a galaxy and the universe?
  38. A galaxy is a collection of hundreds of billions of stars, the universe is a collection of hundreds of billions of galaxies
  39. How many stars are in a typical galaxy?
  40. Hundreds of billions
  1. How many galaxies are in the universe?
  2. Hundreds of billions
  3. How far does light travel in one second?
  4. 300,000 kilometers or 186,000 miles!
  5. Stars range in size. List the 6 basic sizes for stars from smallest to biggest
  6. Neutron star
  7. White dwarf
  8. Average
  9. Giant
  10. Super-giant
  11. Hyper-giant
  12. How do astronomers determine a star’s temperature?
  13. By their color
  14. Stars range in temperature. List the colors of stars from the hottest to the coolest.
  15. Blue
  16. White
  17. Yellow
  18. Orange
  19. Red
  20. What is the Hertzsprung –Russell Diagram?
  21. A diagram that compares the temperature of stars to their luminosity. It shows the relationship between temperature and brightness.
  22. What two characteristics of stars does it compare? (look at the x and y axis for this information)
  23. Temperature and brightness. As temperature increases, so does the luminosity.
  24. What are main sequence stars?
  25. A band of stars within the Hertzsprung-Russell diagram that are found from the upper left to the lower right that shows as temperature of a star increases, so does its brightness
  26. How many of the stars in our universe fall within the main sequence category?
  27. 90%
  28. What is the difference between absolute and apparent magnitude?
  29. Absolute magnitude is how bright a star would look if it were a standard distance (for example 1 light year) from earth. Apparent magnitude is how bright a star looks from however far away is actually is.
  30. Why is absolute magnitude more important when discussing a star’s characteristics?
  31. Because if all stars were a standard distance from earth you could compare their brightness to each other without having to account for how far away they are from Earth.
  32. KNOW HOW TO READ A HERTZSPRUNG-RUSSELL DIAGRAM, THERE WILL BE ONE ON THE TEST
  33. What is a baby star?
  34. Protostar
  35. From what are all baby stars formed?
  36. Nebula
  37. How is the life-span (time a star “lives”) determined in stars?
  38. By how massive it is
  39. How long will a supermassive star typically live?
  40. Just a few million years
  41. How long will an “average” sun-sized star usually live?
  42. About 10 billion years
  43. How long will a smaller star like a white dwarf, neutron star, or any star that is less massive than our sun live?
  44. Up to 200 billion years
  45. From what type of star do neutron stars and black holes form?
  46. Supermassive ones
  47. From what type of star do white dwarfs form?
  48. Average sized stars
  49. What is a quasar?
  50. A very distant galaxy that shines incredibly brightly
  51. What is at the center of any quasar?
  52. A black hole
  53. How is all the light and heat created in a quasar?
  54. When black holes eat stars they pull in the gas very quickly, making it heat up. The gas is moving so fast that it is moving almost at the speed of light, causing quasars to be the brightest objects in the galaxy
  55. What is a star system?
  56. A clump of 2 or 3 stars
  57. What is a star system that is made up of two stars called?
  58. Binary
  59. What is a star system made up of three stars called?
  60. Triple
  61. What is an eclipsing binary star system?
  62. A binary star system in which a brighter and dimmer star orbit each other. When the dimmer star moves in front of the brighter star, it appears to get dimmer, making it look like it is blinking.
  63. How do astronomers find eclipsing binary star systems?
  64. They look for star that get brighter and dimmer at regular intervals
  65. What are the three types of galaxies?
  66. Spiral
  67. Elliptical
  68. irregular
  69. Describe the shape of each type of galaxy
  70. Spiral: A flattened disk with a bulge in the center from which arms radiate out in a pinwheel shape.
  71. Elliptical: A flattened sphere
  72. Irregular: A disorganized or strange shaped galaxy
  73. Describe a characteristic of each type of galaxy
  74. Spiral: Has a lot of gas and dust within the galaxies so there are lots of new stars being born
  75. Elliptical: Galaxies have very little gas and dust so they are made up mostly of old stars
  76. Irregular: Galaxies that are either very young, so they lack a regular shape or are formed when two different galaxies collide.
  77. What is the most massive object in the solar system?
  78. A black hole
  79. Are these big objects or small objects?
  80. Remarkably small
  81. What is the big-bang theory?
  82. A theory that says that about 10-15 billion years ago an enormous explosion occurred and created the universe as we know it today
  83. How long ago do astronomers think the universe was formed?
  84. 10-15 billion years ago