Very interesting. Thanks for posting.

In US night, as defined for pilot certification, flying currency, and
flight logging, does not start at sunset. It starts one hour after
sunset. Flying a day VFR certificated glider 10 seconds after sunset
is not night flying and requires no special pilot qualification. It
does however require the glider to have approved night lighting. I
assume then that a day vfr certificated glider with approved lighting
may legally fly 59 minutes after sunset.

Do any US registered motor gliders have approved lighting? Have their
owners operated between sunset and night?

Andy