Willy Leenders wrote: <Therefore I re-formulate my question in a simple way: Why (in the <northern <hemisphere) the time between spring equinox and summer solstice is <about 1 day <shorter than the time between summer solstice and autumn equinox ?
The astronomical spring (the time interval from March equinox to June solstice) and the astronomical summer (from June solstice from September equinox) would have exactly the same length only if the longitude of the Earth's perihelion was 90 degrees. In that case, the Earth would reach the aphelion point of its elliptical orbit exactly at the time of the June solstice. However, the longitude of the Earth's perihelion presently is 103 degrees, not 90 degrees, and the Earth reaches aphelion around July 5, half a month after the June solstice. For this reason, the Sun's motion along the ecliptic is slowest not on June 21, but on July 5, so the Sun needs approximately 1 more day to travel from the June solstitial point to the September autumnal point. (dixit Jean Meeus) Willy. Willy Ory Petrarcastraat 24 B-3580 Beringen UMI 51,05° N 005,2° E [EMAIL PROTECTED] www.zonnewijzerkringvlaanderen.be ----- Oorspronkelijk bericht ----- Van: Willy Leenders <[EMAIL PROTECTED]> Aan: <[email protected]> Verzonden: dinsdag 26 maart 2002 21:30 Onderwerp: Re: difference between equinoxes and midsummer > > > I received several reactions on my question. Thanks. Most of them gives answers to > another question than mine. > > Only Andrew James gives an answer to my question. > > Maybe my question was formulated not clear. > > Therefore I re-formulate my question in a simple way: Why (in the northern > hemisphere) the time between spring equinox and summer solstice is about 1 day > shorter than the time between summer solstice and autumn equinox ? > > > Willy Leenders > Flanders in Belgium > 50.9 N 5.4 E > > mailto:[EMAIL PROTECTED] > > > > - > -
