Final answer:
The Moon appears less bright than the Sun because it only reflects sunlight compared to the Sun which generates light. The Moon's surface is less reflective and during eclipses, it is illuminated by light refracted through Earth's atmosphere.
Step-by-step explanation:
The Moon appears less bright than the Sun despite its proximity to Earth due to differences in their respective natures. The Sun is a star that produces light through nuclear fusion, emitting vast amounts of light and energy. Conversely, the Moon does not generate light but rather reflects sunlight. The brightness we perceive from the Moon is due to this reflected sunlight.
Furthermore, the Moon's surface is much less reflective than Earth's; it has about the same reflectivity as a landscape of dark rock under sunlight. This lower reflectivity means it sends less light to our eyes compared to the direct light we receive from the Sun. Also, when images of the Moon and Earth are captured, as by the Deep Space Climate Observatory, the exposure is set to capture a bright image of Earth, making the Moon look less detailed and bright.
During a total lunar eclipse, the Moon remains visible and often takes on a reddish hue. This is sunlight that has been refracted or bent into the Earth's shadow by our atmosphere, demonstrating that even in shadow, the Moon reflects and redirects light to a certain degree. Lastly, an interesting phenomenon known as "the new Moon in the old Moon's arms" showcases how earthlight—the sunlight reflected from Earth—illuminates the darkened part of the Moon, providing us with a view of the entire lunar disk even when only a crescent is directly sunlit.