Earthshine lights the Moon's dark face near new and crescent phases.

Earthshine is sunlight reflected from Earth that faintly illuminates the Moon's dark side, most visible around the new Moon and slim crescent phases; it peaks in Northern Hemisphere spring with a smaller peak in Southern Hemisphere spring.

Earthshine is the faint glow seen on the Moon's dark side when sunlight reflected from Earth returns to the lunar surface. It is most visible around the new Moon and when the Moon is a slim crescent. The effect tends to be brightest in Northern Hemisphere spring, with a smaller peak in Southern Hemisphere spring, because snow, sea ice, and seasonal angles increase Earth's reflectivity. An astronaut aboard the International Space Station photographed earthshine on July 31, 2011. Key facts: - Earthshine results from sunlight reflected by Earth (Earth's albedo) that in turn reflects off the lunar surface. - Visibility is strongest near the new Moon and during thin crescent phases. - The Northern Hemisphere spring shows the largest annual peak in reflected light, with a secondary peak in the Southern Hemisphere spring. - Seasonal snow, sea ice, and cloud patterns affect Earth's overall reflectivity and influence earthshine strength. - The phenomenon has been photographed from space and appears in cultural references, such as the song "Earthshine" by Neil Peart. Summary: Earthshine is a recurring natural effect that links seasonal changes in Earth's reflectivity to a faint lunar glow. Undetermined at this time.