1 / 21

Nearby Constellations

Nearby Constellations. (2-D “Constellations”, from Stars in 3-D !). Half-hour time exposure facing north & west. The stars are tracing counter-clockwise circles, centered on a point near the prominent North Star (Polaris). Notice the Big Dipper at the lower-left. “ Circumpolar ”

ferris
Download Presentation

Nearby Constellations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Nearby Constellations

  2. (2-D “Constellations”, from Stars in 3-D!)

  3. Half-hour time exposure facing north & west. The stars are tracing counter-clockwisecircles, centered on a point near the prominent North Star (Polaris). Notice the Big Dipper at the lower-left. “Circumpolar” Stars/Constellations This several-hour-long time exposure, taken from tropical northern Australia, shows the clockwise motion of the southern stars around the South Celestial Pole. (Photo by David Miller/DMI.)

  4. Earth shown at the center of the imaginary “Celestial Sphere”

  5. Celestial coordinates: “Declination” (d) and “Right Ascension” (R.A.) (=> “latitude” & “longitude”!)

  6. The Sun’s apparent path through the Celestial Sphere . . . (actually due to Earth’s annual orbit about the Sun!)

  7. “Summer Constellations” vs. “Winter Constellations”, due to Earth’s annual revolution about the Sun:

  8. Earth, Sun, and the “Zodiac Constellations” through the Seasons “Summer Signs” = “Winter Constellations”; “Winter Signs” = “Summer Constellations”

  9. An Earth-bound Observer sees only half the sky at any one time!

  10. “Time Zones” (artificial!), & some famous Meridians around the globe:

  11. “Northern” vs. “Southern” Celestial Hemispheres (& Northern/Southern Constellations!) (In Northern Winter/ Southern Summer…) =>

  12. What causes the Seasons?

  13. (“Summer” = Higher Sun and Longer Daytimes!)

  14. “Land of the Midnight Sun”? (Or the Noon Darkness…?)

  15. A good view from Stonehenge! (Sunrise on the Summer Solstice)

  16. Ancient “Observatories” in the Americas! (Serving as “Calendars” & “Almanacs”…)

  17. The Sun’s apparent path through the Celestial Sphere goes along the “Ecliptic Plane”… TILTED by ~23.5 with respect to Earth’s Rotation (NP/SP) Axis!

  18. More Tilt with respect to the Sun => Stronger Seasons!

  19. 1 Year  365.2425 Days  365.25 Days (Need “Leap Day” Corrections!) Christopher Clavius The lunar crater Clavius, with peripheral craters Pope Gregory XIII

  20. “Solar Days” (= a day “by the Sun”) (= 24 hrs.) vs. “Sidereal Days” (= a day “by the Stars”) (= 23 hrs., 56 min.) => 1 Year  365.25 Solar Days  366.25Sidereal Days

  21. “Precession” of Earth’s Axis, and the temporary nature of the “North Star” . . . . . . and the “Vernal Equinox”!

More Related