Moon Phase and Visibility Guide for September 20, 2026
Waxing Gibbous phase reveals key lunar features with 64% visibility
1Current lunar phase
As of September 20, 2026, the Moon is in its Waxing Gibbous phase with 64% of its surface illuminated. This phase occurs between the First Quarter and Full Moon, showing more than half but not all of the Moon's face. NASA's Daily Moon Guide provides these precise measurements, tracking the Moon's position relative to Earth and the Sun. The Waxing Gibbous phase offers excellent viewing conditions as the Moon grows brighter each night.
2Visible lunar features
With naked eye observation, viewers can spot Mare Vaporum and Mare Serenitatis (large basaltic plains) along with the prominent Tycho Crater. Binoculars reveal additional details including Alphonsus Crater, Posidonius Crater, and the Apennine Mountains. Telescope users gain access to historic Apollo landing sites from missions 11, 16, and 17. These features become particularly visible during the Waxing Gibbous phase due to favorable lighting angles.
3Lunar cycle mechanics
The Moon completes its orbit around Earth every 29.5 days, creating the lunar phase cycle. Phases change based on the Moon's position relative to both Earth and the Sun. During Waxing Gibbous, sunlight hits the Moon at an angle that illuminates more than half but not all of its Earth-facing side. This geometry creates distinct shadows that highlight surface features, making it prime observation time before Full Moon's flat lighting.
4Eight lunar phases
NASA recognizes eight distinct Moon phases: New Moon (invisible), Waxing Crescent (right sliver), First Quarter (right half), Waxing Gibbous (mostly lit), Full Moon (fully lit), Waning Gibbous (right darkening), Third Quarter (left half), and Waning Crescent (left sliver). Each phase lasts approximately 3.7 days in the 29.5-day cycle. The Waxing Gibbous phase on September 20 precedes the Full Moon by six days, with illumination increasing daily.
5Observation recommendations
The Waxing Gibbous phase provides optimal contrast for viewing lunar features. Craters appear most dramatic along the terminator (light-dark boundary) where shadows are longest. Mare regions show their full extent while mountain ranges cast visible shadows. This phase offers better viewing than Full Moon when surface details become washed out. Optimal viewing occurs when the Moon is high in the sky, away from atmospheric distortion near the horizon.
6Upcoming Full Moon
The next Full Moon will occur on September 26, 2026, completing the current lunar cycle. Full Moons occur when Earth lies directly between the Sun and Moon, fully illuminating the Moon's Earth-facing side. Between September 20-26, observers can watch daily changes as the Waxing Gibbous transitions to Full. The period offers a unique opportunity to track how lighting angles affect feature visibility across different phases.
7Historical observation points
Telescopes can locate Apollo landing sites, including Apollo 11's historic first landing in Mare Tranquillitatis. These sites appear as small, light-colored patches where lunar modules disturbed surface dust. During Waxing Gibbous, sunlight angle helps highlight these artificial features against natural terrain. The phase also provides good visibility of lunar rover tracks and equipment left behind during later Apollo missions.
8Scientific observation value
Waxing Gibbous phase offers astronomers and amateur observers critical data collection opportunities. The phase's lighting conditions allow detailed mapping of crater ray systems and lava flow boundaries in mare regions. Professionals use this phase to study lunar topography changes, while educators find it ideal for teaching lunar geology concepts. The September 20 observation window provides particularly good viewing with 64% illumination before Full Moon's glare.
Original article: Mashable — Moon Phase and Visibility Guide for September 20, 2026