The appearance and visibility of the Moon in the night sky are not random events. The Moon’s distinct phases, along with the precise times it rises and sets, are entirely predictable based on its continuous, cyclical motion. As our natural satellite orbits the Earth, its position relative to the Sun determines how much of its illuminated surface we can see from our vantage point. This predictable geometry is what dictates the visibility and timing of each of the Moon’s eight phases.
The Approximate Rise Time
A Waxing Gibbous Moon generally rises in the mid-to-late afternoon, making it visible well before the Sun fully sets. The timing for this phase ranges from approximately 3 PM to 6 PM local time. This wide window exists because the waxing gibbous phase is a period of transition, lasting about a week between the First Quarter and Full Moon phases.
The specific rise time depends on how far along the Moon is in this seven-day phase. Early in the cycle, just after the First Quarter, the Moon rises closer to 3 PM, but as it approaches the Full Moon, its rise time shifts progressively later toward 6 PM. Regardless of the exact rise time, this Moon phase is visible for a large portion of the night, setting well after midnight.
Characteristics of the Waxing Gibbous Phase
The term “waxing” describes the period when the Moon’s illuminated fraction is increasing, growing larger each night. “Gibbous” is a descriptor for the Moon’s shape when more than half of its face is visible, giving it a humped or bulging appearance. This phase formally begins after the First Quarter Moon, where exactly half the surface is lit, and lasts until the entire face is illuminated at Full Moon.
During the Waxing Gibbous phase, the illumination progresses from slightly more than 50% to nearly 100%. Visually, this is one of the brightest and most prominent phases in the sky, second only to the Full Moon. The phase is a clear signal of the Moon’s progress, showing the gradual build-up of light toward the cycle’s peak illumination.
The Relationship Between Lunar Phase and Rise Time
The time the Moon rises each day is a direct consequence of its orbit around the Earth, which takes approximately 29.5 days to complete a full cycle. The Earth rotates on its axis every 24 hours, but as it spins, the Moon is also constantly moving eastward in its own orbit. Because the Moon advances about 13 degrees in its orbit each day, the Earth has to rotate for an extra 50 minutes, on average, for the Moon to appear at the same point on the horizon.
This daily delay means that each phase has a characteristic rise time relative to the Sun. For example, the New Moon rises with the Sun around sunrise, while the Full Moon, which is opposite the Sun in the sky, rises at sunset. The Waxing Gibbous Moon is positioned between the Sun and the Full Moon in the sky.
Since the Waxing Gibbous phase is positioned three-quarters of the way through the lunar cycle, it is located 135 to 180 degrees away from the Sun. This means the Moon has already traveled a significant distance past the Sun’s position in the sky. Consequently, the Earth’s rotation brings the Waxing Gibbous Moon above the horizon several hours after the Sun has already passed overhead, placing its rise time in the afternoon.
The early rise time of the Waxing Gibbous is why it is often visible during daylight hours. The increasing illumination of this phase reflects so much sunlight that it easily outshines the blue daytime sky. Its position also means it is high in the sky when the Sun sets, making it a prominent feature of the early evening.
Observing the Moon in the Evening Sky
The Waxing Gibbous Moon offers an excellent opportunity for evening observation because its afternoon rise time makes it available throughout the most common viewing hours. When the Sun dips below the western horizon, the Moon in this phase is already substantially high in the eastern or southeastern sky. This placement allows for extended viewing well into the night.
Because it is so bright and visible during prime evening leisure time, the Waxing Gibbous is one of the most frequently observed lunar phases. The large, nearly full illuminated surface provides a clear target for casual observers. The visibility of this bright Moon phase during the early evening hours contributes to its familiarity.