What is the name of the illumination seen on the Moon when sunlight is reflected from Earth and enters Earth's shadow?

• A. Sunlight
• B. Moonlight
• C. Starlight
• D. Earthshine

Answer: (D)

Earthshine is the subtle glow you see on the Moon when sunlight first hits Earth, Earth reflects part of that light back into space, and the Moon reflects that light toward us. Because Earth is brighter and more reflective than the Moon, some of the light bounced off Earth reaches the Moon and then travels to our eyes, making the dark portion of the Moon faintly visible, especially when the Moon is a crescent around new Moon. The other terms describe light from different sources: sunlight is the Sun’s direct illumination, Moonlight is sunlight reflected off the Moon onto Earth, and starlight comes from distant stars.