•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe™

Sitemap

Obliquity of the Equinoxes
Kirt's Cogitations™ #173

These original Kirt's Cogitations™ may be reproduced (no more than 5, please) provided proper credit is given to me, Kirt Blattenberger.

Please click here to return to the Table of Contents.

   Cog·i·ta·tion [koj-i-tey'-shun] – noun: Concerted thought or
                                        reflection; meditation; contemplation.
   Kirt [kert] – proper noun: RF Cafe webmaster.


< Previous                      Next >


Obliquity of the Equinoxes

The Tropic of Cancer and the Tropic of Capricorn are defined as the 23.5° north and south latitudes, respectively, because Earth's 23.5° axis tilt means those are the points where the sun is directly overhead at the vernal and autumnal equinoxes, respectively. At least that is what early observations determined. In reality, gravitational perturbations caused by the sun, planets, asteroids and other minor objects causes the axis tilt to vary between 22.1° and 24.5° during a cycle of about 41,000 years. Current obliquity is decreasing by just under 0.4 arc seconds per year. This effect can account for a solar heating variation of about +/-1% for the +/-1° of tilt. Far larger climate effects are caused by the long-term variations (due to the same forces) in the eccentricity of Earth's orbit, which can vary between 0.0005 (almost circular) to 0.0607 (currently 0.0160) over a period of about 10,000 years. Keep this in mind when reading the next report on global warming; remember in that in the 1960s, and 1970s, the environmental "experts" were in a tizzy over what they were certain was a coming ice age, and were given prime print space in major publications like Fortune, Time, and Newsweek.
Custom Search
More than 10,000 searchable pages indexed.

Your RF Cafe
Progenitor & Webmaster

Click here to read about RF CafeKirt Blattenberger... single-handedly redefining what an engineering website should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5th MOB: My USAF radar shop

Airplanes and Rockets: My personal hobby website

Equine Kingdom: My daughter Sally's horse riding website