๐ Why the terminator? โ 20-second docent script
The terminator is the sunrise/sunset line. Along it the Sun sits just above the lunar horizon, so every crater rim and mountain throws a long black shadow โ that's where the Moon looks three-dimensional. Away from it, under high sun, the same terrain looks flat and washed out.
On the rooftop Takahashi Sky 90, start at ~40ร to frame the whole disc, then push the eyepiece higher on the features listed above. The 30 cm reflector in the dome resolves rilles and craterlets on steady nights. A full Moon has no visible terminator โ switch the story to the bright ray systems of Tycho and Copernicus instead.