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Waning Crescent3.7% Illumination

Moon Phase on 2026-08-11

On 2026-08-11, the Moon is in the Waning Crescent phase. The visible fraction of the lunar disc illuminated by the Sun is 3.7%, with an elapsed synodic age of 27.7 days.

Lunar Phase & Illumination Visualizer

Jean Meeus, Astronomical Algorithms 2nd ed. Chapter 49 (Phases of the Moon)

Illumination = (1 - cos(2π · Phase)) / 2
Select Date:
77% Cycle
Last Quarter
44.1% Illuminated
Visible fraction of the lunar disc facing Earth
0% (New)50% (Quarter)100% (Full)
Moon Age22.7 daysin 29.53d synodic cycle
Phase Angle (k)276.8°geometric elongation
Astronomical Algorithm Note: Moon phases are governed by the synodic month (mean length: 29.53058867 days). Phase zero corresponds to the conjunction of the Moon and Sun (New Moon), while phase 0.50 denotes the exact opposition (Full Moon).

7-Day Moon Phase Progression

DatePhase NameIlluminationMoon AgeLink
Sat, Aug 8
Waning Crescent24.1%24.7 daysView
Sun, Aug 9
Waning Crescent15.7%25.7 daysView
Mon, Aug 10
Waning Crescent8.8%26.7 daysView
Tue, Aug 11
Waning Crescent3.7%27.7 daysView
Wed, Aug 12
New Moon0.8%28.7 daysView
Thu, Aug 13
New Moon0.0%0.2 daysView
Fri, Aug 14
Waxing Crescent1.6%1.2 daysView

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Moon Phase FAQs

Q1.What lunar phase occurs on 2026-08-11?

On 2026-08-11, the Moon is in the Waning Crescent phase, displaying approximately 3.7% disc illumination facing Earth with a lunar age of 27.7 days since the last New Moon.

Q2.How long is a complete lunar synodic month?

A synodic month (from one New Moon to the next) averages 29.53058867 days (29 days, 12 hours, 44 minutes). This duration represents the time required for the Moon to align in the same geometric relationship relative to the Earth and Sun.

Q3.How is the illuminated fraction calculated?

Illumination is determined using Jean Meeus’ trigonometric relation k = (1 - cos(2π · phase)) / 2, where phase is the normalized progress (0.0 to 1.0) along the 29.53-day synodic cycle.

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