why is the moon red

The moon appears red primarily during a total lunar eclipse, often called a "Blood Moon." This red color happens because the Earth comes between the Sun and the Moon, blocking direct sunlight from reaching the Moon. However, some sunlight still passes through Earth's atmosphere, which filters and bends the light so that mostly the longer wavelengths, such as red and orange, illuminate the Moon's surface. This phenomenon is due to Rayleigh scattering, the same effect that causes sunrises and sunsets to appear red on Earth. Shorter wavelengths like blue are scattered out by the atmosphere. The exact shade of red can vary depending on atmospheric conditions, such as dust or clouds. This is why during a total lunar eclipse, the Moon glows with shades of red, orange, or even gold instead of appearing completely dark.