Wonders Of The Sky 2009 Eclipses


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Wonders Of The Sky 2009 Eclipses

  1. 1. Wonders of the Sky
  2. 2. Eclipses
  3. 3. Types of Eclipses <ul><li>Solar: Eclipses of the Sun </li></ul><ul><ul><li>Partial </li></ul></ul><ul><ul><li>Total </li></ul></ul><ul><ul><li>Annular </li></ul></ul><ul><li>Lunar: Eclipses of the Moon </li></ul><ul><ul><li>Partial </li></ul></ul><ul><ul><li>Total </li></ul></ul>
  4. 4. Solar Eclipses <ul><li>Eclipses of the Sun </li></ul><ul><li>Alignment: Sun, Moon, Earth (new moon) </li></ul><ul><li>The moon’s shadow covers part of the earth’s surface </li></ul><ul><li>Last for just a few minutes, total phase often 3-7 minutes </li></ul><ul><li>Types : </li></ul><ul><ul><li>Partial </li></ul></ul><ul><ul><li>Total </li></ul></ul><ul><ul><li>Annular </li></ul></ul>
  5. 5. Eclipse Geometry
  6. 6. Eclipse Map <ul><li>Solar eclipses are only visible in specific areas of earth </li></ul><ul><li>Total Eclipse: Visible in “Path of Totality” </li></ul><ul><li>Partial Eclipses: Visible in red bands </li></ul><ul><li>On average, any location will receive a total eclipse every 400 years </li></ul><ul><li>[ Animation ] </li></ul>
  7. 7. Moon’s Shadow from Mir, 1999
  8. 8. Photosphere <ul><li>Photosphere: The sun’s visible “surface” </li></ul><ul><li>A layer of heated gas </li></ul><ul><li>Sunspots are sometimes visible on the photosphere </li></ul><ul><li>[ current sun ] </li></ul>
  9. 9. SF Partial Eclipse
  10. 10. Partial Eclipse Phases
  11. 11. Eclipse Shadows Above: View of eclipse through a telescope, note the corresponding shadows (right)
  12. 12. June 1994 Eclipse
  13. 13. Bailey’s Beads <ul><li>Bailey’s Beads resemble a string of pearls briefly visible along the edge of the eclipsed sun </li></ul><ul><li>Represent sunlight shining through valleys on the edge of the moon’s disk </li></ul><ul><li>Single bright “bead”, diamond ring effect </li></ul>
  14. 14. Diamond Ring Effect Last remaining bit of sun’s visible surface before totality
  15. 15. Totality <ul><li>At totality, the sun is entirely covered by the moon’s disk </li></ul><ul><li>The corona, the sun’s outer atmosphere, becomes visible as a pearly crown </li></ul><ul><li>The sky becomes dark during totality, bright stars and planets are visible </li></ul>
  16. 16. Totality, Awesome
  17. 17. Chromosphere <ul><li>The sun’s visible disk is the photosphere </li></ul><ul><li>Photosphere visible through thick clouds or a filtered telescope </li></ul><ul><li>Chromosphere is red atmospheric layer on the sun just above the chromosphere </li></ul><ul><li>Chromosphere is only visible briefly during total eclipses of the sun or through expensive solar filters </li></ul>
  18. 18. Chromosphere and Prominences <ul><li>Prominences represent large segments of the chromosphere that can become detached from the sun </li></ul><ul><li>Most prominences are larger than the earth </li></ul>
  19. 19. Chromosphere & Inner Corona
  20. 20. Dark Noon <ul><li>Totality Sky </li></ul><ul><ul><li>Bright stars and planets visible </li></ul></ul><ul><ul><li>Horizon glows sunset colors, “360-Degree sunset” </li></ul></ul><ul><ul><li>Venus, left of eclipsed sun </li></ul></ul>
  21. 21. 360-Degree “Sunset” An all-sky image during totality Note, “sunset” colors surround entire horizon
  22. 22. Eclipse Montage <ul><li>Note partial phases before and after totality (center) </li></ul><ul><li>Sun imaged with solar filter, unfiltered at totality </li></ul>
  23. 23. Shadow Bands <ul><li>Shimmery affect on ground noticed right before start of totality </li></ul><ul><li>Resembles flickering bands of light </li></ul><ul><li>Best seen on white surface (sheet) </li></ul><ul><li>Most likely due to bright, point like light source (diamond ring) distorted by atmospheric air flow </li></ul>Shadow bands, 1870 Italy
  24. 24. Shadow Band Animation
  25. 25. Shadow Band Still Image
  26. 26. Eclipse Safety <ul><li>Caution : </li></ul><ul><ul><li>Partial solar eclipses are not safe to observe with unaided eye </li></ul></ul><ul><ul><li>Total phase of a solar eclipse can be directly observed </li></ul></ul><ul><ul><li>Safe Sunwatching </li></ul></ul><ul><ul><li>Note : Eclipses of the moon are always safe to observe </li></ul></ul><ul><li>Methods : </li></ul><ul><ul><li>Eclipse glasses </li></ul></ul><ul><ul><li>Filtered telescopes </li></ul></ul><ul><ul><li>Projection </li></ul></ul>
  27. 27. Safe-totality NOT safe- partial eclipses
  28. 28. Eclipse Glasses <ul><li>Made from reflective mylar, designed especially for viewing the sun </li></ul><ul><li>Don’t use sunglasses, smoked glass, film negatives, etc. Not safe! </li></ul>
  29. 29. Solar Projection <ul><li>Use a telescope to project the sun’s image onto a flat sheet </li></ul><ul><li>Don’t look into the eyepiece! </li></ul>
  30. 30. Again, Jones’s sneaky colleagues aimed the telescope at the sun…
  31. 31. Pinhole Projection
  32. 32. Eclipse Videos <ul><li>Total Solar Eclipse - Egypt 2006 </li></ul><ul><li>Totality Highlights: Total Solar Eclipse 2008: Live from China </li></ul><ul><li>Perfect Eclipse – Mexico, 1991 </li></ul>
  33. 33. Annular Eclipse <ul><li>“ Ring Eclipse” </li></ul><ul><li>Occurs when moon near apogee, smallest apparent disk </li></ul><ul><li>Moon’s disk not large enough to cover the sun completely </li></ul><ul><li>Unlike true total eclipses, not safe to observe without protection </li></ul>
  34. 34. Eclipse ‘94
  35. 35. Annular Geometry
  36. 36. Lunar Eclipses <ul><li>Eclipses of the moon </li></ul><ul><li>Alignment: Sun, Earth, Moon (full moon) </li></ul><ul><li>The earth’s shadow covers part or all of the moon’s surface </li></ul><ul><li>About 4 hours for complete eclipse, totality can last for nearly an hour </li></ul><ul><li>Unlike solar eclipses, entire night side of earth can witness </li></ul><ul><li>Types : </li></ul><ul><ul><li>Total </li></ul></ul><ul><ul><li>Partial </li></ul></ul>
  37. 37. Lunar Eclipse
  38. 38. Total Lunar Eclipses <ul><li>When eclipsed, the moon usually appears red </li></ul><ul><li>The earth’s shadow has some light directed into it by the edge of earth’s atmosphere </li></ul><ul><li>Similar to red sunset colors </li></ul><ul><li>Video </li></ul>
  39. 39. Lunar Eclipse Partial Stages
  40. 41. Eclipse ’04 Diagram <ul><li>Earth’s shadow has two zones, umbra and penumbra </li></ul><ul><li>Moon passed through dark center of earth’s shadow (umbra) during totality </li></ul><ul><li>Partial eclipses when moon partly immersed in umbra </li></ul>
  41. 42. Eclipse ’04: Red Moon
  42. 43. Earth’s Shadow
  43. 44. Lunar Eclipses <ul><li>Total : Moon passes completely into the earth’s inner shadow (umbra) </li></ul><ul><li>Partial : Moon passes partly into the umbra </li></ul><ul><li>Penumbral : Moon passes only into the earth’s outer shadow (penumbra) </li></ul>
  44. 45. Partial Eclipses: Impossible Lunar “Phases” <ul><li>The moon’s regular phases never appear like this and the following photos </li></ul>
  45. 46. Partial Lunar Eclipse
  46. 47. Penumbral Eclipses <ul><li>Not as dramatic, more difficult to see effect </li></ul><ul><li>Penumbra resembles a slightly darker shading on one half of the moon </li></ul><ul><li>Again, moon passes only through earth’s outer shadow, not the darker umbra in center </li></ul>
  47. 48. Total Lunar Eclipse Dark Sky <ul><li>During a total eclipse of the moon, a bright, full moon-lit sky becomes much darker during totality </li></ul><ul><li>Dimmer stars appear, even the Milky Way and dim celestial objects can be seen </li></ul>
  48. 49. Full Moon Night
  49. 51. Next Eclipses <ul><li>Solar </li></ul><ul><ul><li>America, 2017 </li></ul></ul><ul><li>Lunar </li></ul><ul><ul><li>Dec, 2010 </li></ul></ul>