1 / 23

August 29, 2011: 10am Class

August 29, 2011: 10am Class. On-line Quiz #1 on d2l: Please complete before class on Friday, Sept. 2 HW 2 on line (d2l and boojum ): Create a Constellation Due Wednesday, Sept. 7, in class. Honors Section 3H: Please complete doodle poll (see Megan’s email and class web site)

nizana
Download Presentation

August 29, 2011: 10am Class

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. August 29, 2011: 10am Class • On-line Quiz #1 on d2l: • Please complete before class on Friday, Sept. 2 • HW 2 on line (d2l and boojum): Create a Constellation • Due Wednesday, Sept. 7, in class. • Honors Section 3H: Please complete doodle poll • (see Megan’s email and class web site) • When you go to Mt. Lemmon, bring a flashlight. • Today: Precession, Phases of the Moon, Eclipses, • Seasons

  2. Precession

  3. A spinning top “precesses” http://en.wikipedia.org/wiki/Precession

  4. Precession • The Earth’s axis of rotation precesses, so makes a • big circle, with a period of 26,000 years • (so it goes once around every 26,000 years) • The Earth’s pole moves about one degree in 72 years. • The precession is a result of the fact that the Earth’s • axis of rotation is tilted with respect to the ecliptic, • and with respect to the orbit of the Moon. • The Moon’s and Sun’s gravity tug on the Earth and • cause the pole to precess.

  5. Currently the North Celestial Pole is very near the North Star, Polaris. • In 3000 BC, the pole star was Thuban, in the constellation Draco. • But it is moving away from Polaris: • in 14000 AD, it will be pointed towards Vega, as it was in 12000 BC • Polaris will be the North Star again in 27800 AD. Direction of the North Celestial Pole as a function of year, AD

  6. Direction of the South Celestial Pole as a function of year, AD

  7. Hipparchus of Rhodes (190 BC-120BC) • Precession was first observed by Hipparchus • Also was “father” of trigonometry • Made one of the first star catalogs

  8. The Moon Phases and Eclipses

  9. We always see the SAME SIDE of the Moon because the moon orbits the Earth and rotates on its axis with EXACTLY the same period (29 ½ days). The “DARK SIDE OF THE MOON” was not seen by any human until spacecraft were sent to the moon and photographed it, in the 1950s.

  10. Rotation of the Moon Applet Animation

  11. Near Side of the Moon Far side of the Moon

  12. 24 hour cycle of the Earth

  13. PHASES

  14. The Moon appears to go through a series of PHASES during each month: new moon, crescent, gibbous, full, gibbous, crescent, new. Phases of the Moon youtube.com rap.

  15. Lunar Eclipse = Earth's shadow falls on the Moon

  16. Solar Eclipse = Moon's shadow falls on the Earth

  17. Cause of Eclipse Animation

  18. Path of some Solar Eclipses on the Earth

  19. Solar Eclipses: Total Partial Annular

  20. Examples of Beautiful Eclipses!

More Related