The Moon
The most visible cycle in the sky.
The 29.5-Day Cycle
The Moon completes one full cycle of phases — new moon to full moon and back — in 29.5 days. This is the synodic month: the time it takes for the Moon to return to the same position relative to the Sun as seen from Earth. The cycle never breaks. It has been running since before humans existed to name it.
The phases are caused by geometry, not by Earth's shadow. The Moon is always half-lit by the Sun. What changes is which half we can see from Earth as both bodies move through their orbits.
The Eight Phases
The Moon is between Earth and Sun. The dark side faces us. The sky is at its darkest — best nights of the month for deep sky objects.
A thin crescent appears after sunset, growing each night. Sets a few hours after the Sun. The early night is dark.
Half the Moon is lit. Rises at noon, sets around midnight. The second half of the night is dark.
More than half illuminated. Rising in the afternoon. The sky fills with moonlight through the night.
The Moon is opposite the Sun. It rises at sunset and sets at sunrise. The sky is flooded with reflected sunlight all night.
Past full and fading. Rises after sunset, high overhead at midnight. Still bright enough to affect deep sky viewing.
Half-lit again, but now decreasing. Rises around midnight. The early night is dark before it rises.
A thin crescent visible before dawn. Rising a few hours before the Sun. The nights are getting darker again.
Lunar Eclipses
A lunar eclipse occurs when Earth moves between the Sun and Moon, casting its shadow on the Moon. Unlike solar eclipses, lunar eclipses are visible from everywhere on Earth that the Moon is above the horizon. The Moon turns red — lit by the glow of every sunrise and sunset happening simultaneously on Earth's rim.
Track the Moon in real time. Tonight's phase, illumination, and voice — every night, in Campfire.
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