Sidereal solar return

Sidereal solar return is, for a given birthday (for example 20 years), the horoscope of this moment.

The place of the sidereal solar return is a matter of discussions.
It can be the place where the person finds herself at birthday moment, or the place where the birth took place.

The exact moment of the sidereal solar return happens when the sun is at the same longitude as it was at birth time.

But we have to be more precise with the meaning of "same longitude".
If we put that it is the same longitude from the vernal point we must not forget that vernal point is not fixed is regard to stars, but move 50 seconds of arc per year.

Then we can reach half a day difference, for the sidereal solar return of the 40-year birthday, between sun longitude from vernal point and sun longitude from zero of Aries constellation.

Sidereal solar return takes effect from one birthday to the next one.

This predictive system seems to give bad results for a horoscope with Sun weak.

See also:

Ayanamsa