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Introduction to the Sky

Introduction to the Sky. Capella. Sirius. Aldebaran. Orion. Pleiades. Comet Hale-Bopp. Mars. Orion. “ Observation ” is not “ Looking ” Instead: . Study carefully Remember/record Try to make connections Identify systematic features. Motivations for Observing the Sky.

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Introduction to the Sky

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  1. Introduction to the Sky

  2. Capella Sirius Aldebaran Orion Pleiades Comet Hale-Bopp

  3. Mars Orion

  4. “Observation” is not “Looking”Instead: • Study carefully • Remember/record • Try to make connections • Identify systematic features

  5. Motivations for Observing the Sky • Curiosity • Practical applications • Navigation • Time-keeping • Calendar-keeping • Fear, religious belief • E.g. Astrology

  6. Egyptian Pharoh Akhenaton and family communing with Sun God (ca. 1350 BC)

  7. Polynesian Navigation

  8. Astronomical Measurements Without Telescopes • Angles (quantitative) • Sky to Sky • Earth to Sky • Brightnesses (crude) • Colors, Shapes (crude) • Changes in above with time

  9. Units of Angular Measure

  10. Naked Eye Instruments for Angular Measures 1580 AD 150 BC

  11. Naked Eye Instruments for Angular Measures Limiting accuracy ~ resolution of human eye ~ 1 minute of arc 1580 AD 150 BC

  12. 10 degrees 5 degrees Ursa Major (The Big Dipper)

  13. "Hand-y" Angle Measuring (crude)

  14. The Magnitude System(a brightness ranking)

  15. Example: Range of magnitudes in Big Dipper

  16. Star Colors (prism-dispersed image)

  17. Constellations • Constellations are the patterns formed by brighter stars on the sky • Patterns seem fixed (i.e. don't change over years) • Recognized for millenia, by all cultures • Associated with mythological figures, animals, instruments, etc

  18. Stick-Patterns

  19. Official Names

  20. "Classical" figures added

  21. Mesopotamian carved stone, ca. 1000 BC showing Sun, Moon, Venus, and constellations

  22. Greek amphora, ca. 400 BC, showing Leo, Aquila, Hercules, etc

  23. Orion, Taurus, Lepus in a classical celestial atlas.

  24. Pattern only traces the brighter stars in each region

  25. Hevelius, Firmamentum 1690

  26. Hevelius, Firmamentum 1690

  27. Cellarius, HarmoniaMacrocosmica, 1661

  28. More modern constellations Bode, 1801

  29. "Asterism"

  30. Modern Constellations • "Official Constellations": 88 (est. 1930, IAU) • Boundaries of each well-defined • "Zodiac" = the 12 (13) constellations lying along the annual path of Sun through stars. (Names widely recognized but NOT all bright.)

  31. Significance of the Constellations? Not Much • Associations are arbitrary, man-made, culture-specific. • Not natural groupings: stars not necessarily close in 3D space. Shapes are specific to Earth's location in galaxy. • Constellations are transient because stars are all moving with respect to each other. • Used as convenient "address" for roughly locating objects in sky.

  32. Contemporary "constellations"

  33. Orion Projected View 3-D Distribution

  34. Motions in Big DipperOver 100,000 Years

  35. Constellation Quiz • Two one-hour sessions offered M-R, 9 pm and 10 pm • Must reserve a place using on-line registration system • No special preparation needed • Bring a flashlight (red preferred), pencil, and clipboard (if you have one) • Cloudy or rainy weather will cancel the session • Check weather status after 6:30 pm at 924-7238

  36. -- END --

  37. Capella Sirius Hyades Orion Pleiades Comet Hale-Bopp

  38. Light Pollution = Wasted Energy

  39. Astrological ("Zodiacal") Signs

  40. Astrological Traits Associated With Planets

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