do natal planets "cast rays" and proper orb for tr

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This is a question which has been puzzling me for a few days. I can't really figure out how to properly calculate orbs when it comes to transits. I mean, should we only use the moiety of the transiting planet itself? Or do we want to combine the moiety of the transiting planet and the aspected natal planet as well? Intuitively, I feel like we should only use the moiety of the transiting planet itself, since it is the only planet that is "alive" and thus capable of giving light. However I don't really have any solid backing for this notion, its just a hunch.

OTOH, the concept of casting rays is inherently a metaphysical concept to begin with, so it wouldn't be too farfetched to assume that even natal placements still emit a certain orb in spite of them not being a real time occurrence. My rationale backing this idea is that people's planets aspect in synastry. If we were to assume that natal positions were no longer capable of casting rays (big apologies if I am using the incorrect term here) then synastry would not really be possible at all since neither parties planets are casting rays to each others. Another example to support this line of reasoning is looking at solar return charts, and when SR angles or planets aspects angles or planets in the natal chart. (and vice versa of course) If past placements of planets (either natal or in solar return chart) were incapable of casting rays then we would also have to disregard these kinds of aspects as well. So all of that being said, what do you all think about it? I feel like this should be a fairly basic concept to understand, but for some reason it has gone completely over my head.