This simulator demonstrates the correspondence between the moon's position in its orbit, its phase, and its position in an observer's sky at different times of day.

The upper left panel shows the orbit visualization. The moon can be dragged around to change its position, and the earth can be dragged around to change its rotation. You can also use the Animation and Time Controls panel to control the simulation.

The Moon Phase panel shows how the moon would appear from earth given the geometry shown in the visualization panel. The Horizon Diagram panel shows how the sky would appear for the stickfigure shown standing on the globe. Note that this horizon diagram assumes an observer in the mid-northern latitudes (e.g. the continental US).

Checking the show angle checkbox in the Diagram Options panel will show the elongation angle of the moon in the visualization panel as well as the horizon diagram. The lunar landmark option lets you see a reference point on the moon's near side, which also shows up in the Moon Phase panel. The time tickmarks show the time of day for various positions around the globe.

You may notice that the Moon Phase and Horizon Diagram panels have a show/hide button. This feature can be useful when using the simulator as a demonstration tool in the classroom. For answering questions in the student guide you will want to keep the panel contents shown.

lunar-phase-simulator 1.0.1 (build date: 2021-03-22)

See github.com/ccnmtl/astro-interactives for more info.