"Sonderegger" <[EMAIL PROTECTED]> writes: > I think in the northern hemisphere summer is always in July, because the > beginning of spring is here always when then sun crosses declination of 0 > degree from south to north (= crossing the ecliptic). The places of the > stars on then sky will change in this 13000 years.
Right. The question is not whether summer will be in July, but whether July will be in summer. That only depends on how you choose your calendar system. The Gregorian calendar reform was an effort to keep July in the summer. The precession is a physical process, which does not depend on our calendars. What it does is change the constellations that are visible at night in July. Since we don't use the stars for sundials, it won't make any difference. What will matter is the Equation of Time, as mentioned by Luke Coletti. I think the processes which change the eccentricity and obliquity of the Earth's orbit work on a much slower time scale than the precession of the equinoxes, so that we can still use the same Equation of Time 13,000 years from now. Does anybody know for sure about this? Art Carlson
