Look up at the sky in the upcoming week, and you may be fortunate enough to witness the ethereal Da Vinci glow. This captivating phenomenon typically occurs during sunset when a crescent moon is positioned on the horizon, resulting in the visible outline of a full moon. According to Christine Shupla, the science engagement manager at the Lunar and Planetary Institute in Houston, the Da Vinci glow is a frequently observed event and easily discernible. However, its occurrence was once shrouded in enigmatic allure.

NASA reveals that the mysterious phenomenon of the ghostly full moon effect, also known as "the old moon in the new moon's arms," was an age-old question that Leonardo da Vinci shed light upon. Surprisingly, the answer lies in the illumination originating from Earth.

Different from sunlight, Earthshine denotes the radiance emitted by our planet even after the sun has set. NASA explains that this Earth-generated light source is approximately 50 times brighter than the illumination produced by a full moon.

During the time Leonardo contemplated this phenomenon, Copernicus had not yet published his theory that the Earth revolves around the sun. Nevertheless, utilizing his artistic comprehension of light and shadow, combined with his engineering understanding of geometry, Leonardo managed to discern the source of the ashen glow surrounding the crescent moon, as stated by NASA.

Leonardo's hypothesis regarding Earth reflecting light, enabling the visibility of the moon's outline, proved to be correct. However, further insights were gained by the astronauts of the Apollo 11 mission in 1969. As they gazed upon Earth, they discovered that the light was not reflected solely by the oceans, as Leonardo had presumed, but also by the clouds, as indicated by NASA.

According to Shupla, anyone with a view of the moon has the potential to witness the Da Vinci glow, although specific conditions must be met for it to occur. Shupla explained that the phenomenon is most visible during a waxing or waning crescent phase. To observe it, clear skies are necessary to see the moon itself, while certain parts of the Earth should have sufficient cloud cover to reflect a significant amount of light onto the moon. Shupla suggests that sky watchers should keep an eye out for the banana-shaped crescent moon in the evening around sunset and attempt to observe the remainder of the moon, faintly illuminated by Earth's reflected light.