Moon Phases Almanac

Moon Phases Almanac

Moonrise and Moonset: Why the Times Shift Every Day

Moonrise comes about 50 minutes later each day, and that single drift explains why every phase keeps its own hours of darkness and daylight.

The cause is the Moon's own motion. It travels about 13.2° per day eastward around the Earth, while the Earth rotates 360° in roughly 23 hours 56 minutes. Each day the Earth must therefore turn about 13.2° further — close to 50 minutes of rotation — to bring the Moon back over the same meridian.

Anchor the drift to the four principal phases. A new moon rises near sunrise, crosses the meridian near noon and sets near sunset. A first quarter rises near noon, stands highest near sunset and sets near midnight — which is why it is visible from about noon to midnight. A full moon rises near sunset, transits near midnight and sets near sunrise. A last quarter rises near midnight, stands highest near sunrise and sets near noon.

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The intermediate phases fill the gaps at roughly three-hour steps, because 50 minutes a day over the 3.7 days between neighbouring phase marks adds up to about three hours: waxing crescent rises mid-morning and sets in the evening; waxing gibbous rises mid-afternoon and sets after midnight; waning gibbous rises in the mid-evening and sets mid-morning; waning crescent rises before dawn and sets in the afternoon.

Treat the 50 minutes as an average, not a promise. The Moon's orbit is tilted about 5.1° to the Earth's orbit, so the Moon's daily path meets the horizon at a changing angle, and the real delay from one day to the next can run well under or well over 50 minutes. The further you observe from the equator, the stronger this stretching and compressing becomes, and at high latitudes successive moonrises can bunch together or skip a calendar day entirely.

Distance plays a quieter role: the orbit carries the Moon from about 363,300 km at perigee to 405,500 km at apogee, while its apparent width stays near 0.5°, about 30 arcminutes. For the phase that matches each rise time, see The Eight Moon Phases Explained (/moon-phases-explained); to predict the phase for a future date, use the arithmetic on How to Calculate the Moon Phase for Any Date (/calculate-moon-phase).

  • New — rises near sunrise — transits near noon — sets near sunset
  • First quarter — rises near noon — transits near sunset — sets near midnight
  • Full — rises near sunset — transits near midnight — sets near sunrise
  • Last quarter — rises near midnight — transits near sunrise — sets near noon
  • Daily slip: about 50 minutes later, on average

Further reading