Understanding Moon Phases

New Moon

New Moon

The moon is positioned between Earth and the Sun. The illuminated side faces away from Earth, making it invisible in the night sky.

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Waxing Crescent

Waxing Crescent

A thin sliver of the moon becomes visible as it moves away from the Sun's glare. The illuminated portion grows each night.

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First Quarter

First Quarter

Half of the moon's visible surface is illuminated. This occurs about a week after the new moon.

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Waxing Gibbous

Waxing Gibbous

More than half of the moon is illuminated and continues to grow. The word "gibbous" means humped or bulging.

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Full Moon

Full Moon

The entire face of the moon is illuminated by the Sun. Earth is positioned between the Sun and moon.

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Waning Gibbous

Waning Gibbous

The illuminated portion begins to shrink after the full moon. More than half remains visible.

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Last Quarter

Last Quarter

Half of the moon is illuminated, but the opposite half from the first quarter. Occurs about three weeks after the new moon.

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Waning Crescent

Waning Crescent

Only a thin sliver remains visible as the moon approaches the new moon phase again, completing the 29.5-day cycle.

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Lunar Cycle Facts

  • A complete lunar cycle takes approximately 29.53 days
  • The moon orbits Earth at an average distance of 238,855 miles (384,400 km)
  • The same side of the moon always faces Earth due to tidal locking
  • A "blue moon" refers to the second full moon in a calendar month
  • The moon's gravitational pull causes ocean tides on Earth