Calculate and visualize moon phases for any date. Shows illumination percentage, rise/set times, and lunar calendar.
Choose a date to see the corresponding lunar phase, the illuminated portion of the Moon's apparent disk, a phase visualization, rise and set information, and the surrounding lunar calendar. The phase and illumination describe the Sun-Earth-Moon viewing geometry for that date. Rise and set times are different: they depend on the observer's location, time zone, and civil date. A frequent surprise is that the same illumination percentage can occur while the Moon is waxing and again while it is waning, so the percentage alone does not identify the phase.
The phase name identifies a portion of the repeating sequence from new moon through first quarter, full moon, last quarter, and back to new moon. Illumination is the percentage of the apparent lunar disk lit by the Sun from an Earth-based viewpoint. The waxing or waning direction distinguishes dates that otherwise have similar illumination percentages.
Moonrise and moonset are horizon events tied to a particular observing location and local date. They do not occur at a fixed clock time for a given phase. The lunar calendar places daily results next to one another, making changes in phase and illumination easier to follow. Some civil dates, especially at high latitudes, may lack a rise or set event.
Illumination increases from new moon toward full moon and then decreases from full moon toward new moon. A percentage can therefore occur on both sides of the cycle. The waxing or waning designation, together with the phase name or calendar sequence, tells you which side applies. Rounded percentages can also make nearby dates appear identical.
No. Moonrise marks a calculated crossing of the local horizon, not guaranteed visibility from a particular window, street, or landscape. Hills, trees, buildings, haze, clouds, and bright twilight can delay or prevent a practical sighting. The time is most useful for planning when the entered location and time zone match the observation site.
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