1 / 8

Vernal Equinox, the First Day of Spring

Vernal Equinox, the First Day of Spring. By Dr. Harold Williams of Montgomery College Planetarium http://montgomerycollege.edu/Departments/planet/. The Sky Dome. Sunrises and Sunsets. Polaris. On the day of an summer solstice…. W. On the day of an winter solstice…. S.

chancellor
Télécharger la présentation

Vernal Equinox, the First Day of Spring

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. Vernal Equinox, the First Day of Spring By Dr. Harold Williams of Montgomery College Planetarium http://montgomerycollege.edu/Departments/planet/

  2. The Sky Dome Sunrises and Sunsets Polaris On the day of an summer solstice… W On the day of an winter solstice… S On the day of an equinox… N E

  3. Polaris W Vernal or Autumnal Equinox Winter Solstice S Summer Solstice N E Starting Points for the Sun

  4. Length of Seasons • Summer 93 days 15 hours 29 minutes • Autumn 89 days 20 hours • Winter 88 days 23 hours 54 minutes • Spring 92 days 18 hours 26 minutes Sun and Earth closest, perihelion Around January 3 or 4 Sun and Earth furtherest, aphelion Around July 4

  5. Obliquity of the ecliptic • 23 ½ degrees, approximately, between day axis of rotation and year axis of revolutionary orbit about the sun • Causes the seasons • Seasons are not caused by the fact that the earths orbit is not a perfect circle, but its orbit is slightly elliptical. • This ellipticity of the earths orbit does cause the seasons which are caused by the tilt, obliquity of the ecliptic, to be slightly unequal in length.

  6. Equinoxes and Solstices • The Vernal (Spring) Equinox(about March 21): The location where the Sun crosses the equator when going from south of the equator to north of the equator. • Position of the Sun: R.A. 0h, Dec 0o • The Summer Solstice(about June 21): The location where the Sun is at its furthest north. • Position of the Sun: R.A. 6h, Dec +23.5o

  7. The Autumnal (Fall) Equinox(about September 21): Where the Sun crosses the equator when going from north to south. Position of the Sun: R.A. 12h, Dec 0o The Winter Solstice(about December 21): The location where the Sun is at its furthest south. Position of the Sun: R.A. 18h, Dec –23.5o Equinoxes and Solstices

  8. Some Resources on Seasons • Seasons in the Wikipedia http://en.wikipedia.org/wiki/Seasons • Spring Seasons in the Wikipedia http://en.wikipedia.org/wiki/Spring_%28season%29 • Tropical Year in the Wikipedia http://en.wikipedia.org/wiki/Tropical_year

More Related