Case study · UK
Moonrise, Snowdonia
Eryri
A full Moon over Tryfan is the Moon opposite the Sun. The same night, California sees the same phase.
Locator · OpenStreetMap / OpenFreeMap · 53.07°, -4.08°
Phase is global. Rise time is local, because Earth is still rotating. Full Moon plus a node crossing would be a lunar eclipse. Most months, the Moon misses Earth’s shadow by 5° of orbital tilt.
The moon-phases lab’s UK/US night-sky inset is this sentence. Photographers wait on geometry, not on a different Moon.
Exam-style question
Why can two observers, one in Snowdonia and one in Yosemite, see the same lunar phase on the same date but at different clock times?
Teacher hint: Phase: Sun–Moon–Earth angle. Clock time: rotation and longitude.
Process labs
Sources
- NASA Moon phases