Nocturnal Stars and the Diurnal Moon
Ordinarily, the moon and stars are obscured during daylight hours because the brilliance of the sun overpowers their faint luminescence in the sky. Science enthusiasts would elaborate that the stars are, in fact, still present, but their visibility is diminished by sunlight scattered within Earth's atmosphere.
The moon, Earth's natural satellite, stands out as an exception primarily due to its inherent brightness, which renders it discernible against the illuminated or azure backdrop. Additionally, there are periods when the moon occupies Earth's horizon simultaneously with the sun.
The Moon's Reflective Nature and Its Daytime Presence
Contrary to popular belief, the moon does not emit its own light. Instead, it reflects sunlight, illuminating Earth's night sky. Interestingly, the moon possesses a rather dark surface, reflecting only about 3% of the sun's rays that strike it. Yet, this seemingly meager amount is sufficient to illuminate our planet.
Despite falling short of the sun's brilliance, moonlight outshines the brightest stars. Consequently, the moon's radiance can penetrate the white light of the daytime sky, allowing us to perceive it even when the sun dominates the celestial stage (i.e., during midday).
Earth's Rotation and the Moon's Daytime "Display"
The visibility of the moon from Earth is contingent upon its position within its orbit. The moon takes approximately 29.5 days to complete its orbit around Earth, exhibiting distinct appearances during this period. These forms are commonly referred to as the moon's eight phases (illustrated below).
The moon's shape when visible in the sky corresponds to the angle at which sunlight illuminates its surface.
Consider the full moon phase as a representative example. At this point, the moon is positioned opposite the sun in the sky, causing it to rise as the sun sets. Thus, during every full moon, the trio of the sun, moon, and Earth align in a manner that allows us to witness both sunset and moonrise concurrently.
Post-full moon, the moon draws closer to the sun each day, eventually reaching a point where it closely approximates the largest planet in the solar system (near the new moon phase). Consequently, it rises and sets nearly simultaneously with the sun. This phenomenon reduces the moon's nighttime visibility while increasing its daytime presence.
As Earth perpetually rotates, the moon remains above the horizon for approximately 12 out of 24 hours each day. On certain days, these 12 hours coincide with the sun's presence above the horizon. Lo and behold, the conditions are ripe for daytime moon viewing.
Thereafter, the moon gradually recedes from the sun until the full moon phase is attained, at which point the cycle repeats.
Ideal Conditions for Daytime Moon Observation
The moon's ability to grace us with its presence in the daylight has some limitations, including seasonality, its current phase, and the clarity of the sky on a given day.
On average, the moon grazes the daytime sky for roughly 25 days per month throughout the year. Around the new moon phase, it resides too close to the sun for easy visibility, while near the full moon phase, it only ventures into the daytime realm, rising at sunset and setting with sunrise. The full moon phase is the sole exception, as it never coincides with daylight hours (i.e., the sun sets before the moon rises, and vice versa).
Shorter daylight hours in mid-latitudes during winter reduce the likelihood of spotting the moon during the day. According to astronomers, the optimal periods for daytime moon sightings are the week following a new moon, when it can be found in the eastern sky, and the week after a full moon, when it graces the western sky. These timeframes represent the moon's harmonious coexistence with the fiery celestial orb.