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Waning Gibbous97.8% Illumination

Moon Phase on 2026-08-29

On 2026-08-29, the Moon is in the Waning Gibbous phase. The visible fraction of the lunar disc illuminated by the Sun is 97.8%, with an elapsed synodic age of 16.2 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
Wed, Aug 26
Waxing Gibbous97.2%13.2 daysView
Thu, Aug 27
Full Moon99.6%14.2 daysView
Fri, Aug 28
Full Moon99.8%15.2 daysView
Sat, Aug 29
Waning Gibbous97.8%16.2 daysView
Sun, Aug 30
Waning Gibbous93.6%17.2 daysView
Mon, Aug 31
Waning Gibbous87.4%18.2 daysView
Tue, Sep 1
Waning Gibbous79.5%19.2 daysView

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Moon Phase FAQs

Q1.What lunar phase occurs on 2026-08-29?

On 2026-08-29, the Moon is in the Waning Gibbous phase, displaying approximately 97.8% disc illumination facing Earth with a lunar age of 16.2 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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