A young crescent moon appearing low in the sky after sunset this week will showcase the astronomical phenomenon known as earthshine. The event occurs when sunlight reflects off Earth's surface and atmosphere, creating a faint illumination of the moon's otherwise dark regions.
The phenomenon becomes visible when the moon is in its crescent phase, allowing observers to see both the brightly lit crescent portion and the dimly glowing "dark" side. The soft, ashen light reveals details of the lunar surface that would otherwise remain hidden in shadow.