Why Does the Moon Shine? The Science of Lunar Reflection

No, the Moon does not generate its own visible light. It shines by reflecting sunlight off its surface. Despite appearing bright in the night sky, the Moon reflects only about 12 percent of the light that hits it, a measurement known as its albedo.

The Moon's surface is primarily composed of dark rocks similar to coal. It appears bright due to the contrast against the dark sky; however, its Bond albedo is only about 0.11, meaning it absorbs 89 percent of the sunlight that strikes it.

The average distance between the Earth and the Moon is 384,400 kilometers (238,855 miles). Since light travels at 299,792 km/s, it takes approximately 1.28 seconds for the reflected sunlight to travel from the Moon to Earth.

A Full Moon is roughly 6 to 10 times brighter than a Half Moon. This is because when the Moon is full, the Sun is directly behind the Earth, causing shadows on the lunar surface to disappear from our perspective, a phenomenon called the opposition surge.

The Moon's orbit is elliptical, ranging from 363,300 km at perigee to 405,500 km at apogee. When a Full Moon occurs at perigee, also known as a Supermoon, it can appear up to 14 percent larger and 30 percent brighter than a Full Moon at its farthest point.