8th Grade Chapter 1 Lesson 4


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8th Grade Chapter 1 Lesson 4

  1. 1. 8 th Grade Chapter 1 Lesson 4 Pgs. 27-32 For Student Use Only
  2. 2. Star Magnitude <ul><li>Star Appearance: Some stars appear brighter than other stars </li></ul><ul><li>Apparent Magnitude- the brightness of a star as it appears to an observer on Earth. </li></ul><ul><ul><ul><li>Depends on 2 things: </li></ul></ul></ul><ul><ul><ul><ul><li>Actual Brightness </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Distance from the earth </li></ul></ul></ul></ul>
  3. 3. Star Magnitude <ul><li>Hipparchus developed the system for classifying stars based on their brightness. </li></ul><ul><ul><li>First Magnitude Stars= Brightest </li></ul></ul><ul><ul><li>Sixth Magnitude Stars= Faintest </li></ul></ul><ul><ul><li>The lower the apparent magnitude- the brighter the star. (NOTE: Stars can go negative on the scale) </li></ul></ul>
  4. 4. Star Magnitude <ul><li>Apparent Magnitude measures the brightness of stars, but we first must know the distance of the star. </li></ul><ul><ul><li>Apparent Magnitude is calculated by the inverse square law . </li></ul></ul><ul><ul><li>Inverse Square Law states: the brightness of a star varies inversely as the square of the distance from the star. </li></ul></ul>
  5. 5. Star Magnitude <ul><li>We can also calculate how bright stars really are ( absolute magnitude ) by using their distance and apparent magnitude. </li></ul><ul><ul><li>Absolute Magnitude : The brightness of the star if all stars were the same distance from Earth. Astronomers use the distance of 10 parsecs from Earth. </li></ul></ul><ul><li>Absolute Magnitude depends on 2 things: </li></ul><ul><ul><li>Surface Temperature </li></ul></ul><ul><ul><li>Size </li></ul></ul>
  6. 6. Star Colors <ul><li>Surface Temperature causes different colors in stars. </li></ul><ul><ul><li>Red Stars- cooler stars </li></ul></ul><ul><ul><li>Yellow stars- warmer stars </li></ul></ul><ul><ul><li>White stars- hot </li></ul></ul><ul><ul><li>Blue-white stars= hottest </li></ul></ul>
  7. 7. Star Colors <ul><li>Although some stars are hotter than others, cooler stars can outshine hot stars because of bulk. </li></ul><ul><ul><li>Size of stars help them to shine brighter. </li></ul></ul><ul><ul><ul><li>Bigger cooler stars can outshine smaller hot stars. </li></ul></ul></ul>
  8. 8. Star Colors <ul><li>Giants and Dwarfs: </li></ul><ul><ul><li>GIANTS : These stars are extremely bright for how cool they are. That is because they are BIG! </li></ul></ul><ul><ul><li>Dwarfs : Star that are smaller. </li></ul></ul><ul><ul><ul><li>White dwarfs are stars that are smaller and dimmer than average stars. </li></ul></ul></ul>
  9. 9. Stars <ul><li>Some stars are binary stars : </li></ul><ul><ul><li>2 stars that orbit together are a double star. </li></ul></ul><ul><ul><ul><li>Sirius and Sirius B (The Pup) are binary stars. </li></ul></ul></ul><ul><ul><li>Optical doubles: can be confused with binary stars. These are stars that appear to be close together from Earth, but are actually far apart. </li></ul></ul>
  10. 10. Stars <ul><li>Stars also can occur in groupings called star clusters . </li></ul><ul><ul><li>Globular Cluster: groups of stars that travel together </li></ul></ul>
  11. 11. Stars <ul><li>Star Explosions: </li></ul><ul><ul><li>Occasionally stars flare up and become very bright this is call a NOVA . </li></ul></ul><ul><ul><ul><li>During a NOVA a star will become very bright but eventually return to its normal size </li></ul></ul></ul><ul><ul><li>Occasionally stars also flare up so large that they become SUPERNOVAS! </li></ul></ul><ul><ul><ul><li>A SUPERNOVA is an explosion of a star. </li></ul></ul></ul>