Lunar phase

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A lunar phase is the apparent shape of the illuminated portion of the Moon as seen from Earth. The phases result from the changing geometry among the Sun, Earth, and Moon as the Moon travels around Earth.

The principal phases are new moon, first quarter, full moon, and last quarter, with waxing and waning crescent and gibbous phases between them. The complete sequence repeats over the synodic month, averaging about 29.53 days.

At new moon, the Moon lies near the direction of the Sun, while at full moon it is opposite the Sun in the sky. Quarter phases occur when the angle between the Sun and Moon is about 90 degrees as viewed from Earth.

Lunar phases influence calendars, tides, eclipse timing, night-time illumination, cultural traditions, and biological rhythms in some organisms. The Moon itself is always half illuminated by the Sun except during a lunar eclipse.

Source details and credits

• Source / publisher: Wikipedia
• URL type: WWW
• Credits: Wikipedia
• URL: https://en.wikipedia.org/wiki/Lunar_phase