Observing glossary
What does meridian passing mean for the Moon?
Meridian is an imaginary great circle passing through the north point, zenith, and south point of an observer's sky.
Also called: Meridian passing, Upper transit, Culmination
What it means
When a Moon calendar lists meridian passing, it means the Moon is crossing your local meridian. This is usually when the Moon reaches its highest altitude for that passage, although the exact height depends on your location and the Moon's declination. The event is also called upper transit or culmination.
A meridian passing is a type of transit, not a moonrise. Moonrise happens when the Moon appears at the horizon; meridian passing happens later, as the Moon crosses the north–zenith–south line in your local sky.
Sources and further reading
This definition was written in plain language and checked against these science references.
