Phases and Tides of the Moon

Lunar Phases

The Moon's phases result from our view of the sunlit portion of the Moon as it orbits Earth:

• New Moon - Moon between Earth and Sun; dark side faces Earth.
• Waxing Crescent - Growing sliver of light on the right.
• First Quarter - Right half illuminated.
• Waxing Gibbous - More than half illuminated, still growing.
• Full Moon - Earth between Sun and Moon; fully illuminated.
• Waning Gibbous - More than half illuminated, shrinking.
• Last Quarter - Left half illuminated.
• Waning Crescent - Shrinking sliver on the left.

The complete cycle takes about 29.5 days (a synodic month).

Tides

Tides are caused by the gravitational pull of the Moon and Sun on Earth's oceans:

• Spring Tides - At new and full moon, Sun and Moon align, producing higher high tides and lower low tides.
• Neap Tides - At first and last quarter, Sun and Moon pull at right angles, producing less extreme tides.

The Moon's gravitational effect is about twice as strong as the Sun's because it's much closer to Earth.