I do not know enough, or care enough to find out currently, about the predicted motions of Moon & Venus. My interest in this thread is due to issues of and with DateTime*.

Q1) Have we agreed that I'm gonna end up with seconds from DateTime::Duration*, and I might as well roll my own days, hours, minutes, seconds from that?

Looks so: I suggested to convert human readable string based on *::Duration documentation; you seem to want to do so.

In reply to Re^3: Display of DateTime::Duration object in human readable string by parv
in thread iterating over time with DateTime to obtain values with Astro::Coords by Aldebaran

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