what makes a blood moon red

A blood moon appears red because during a total lunar eclipse, Earth passes directly between the Sun and the Moon, blocking most direct sunlight from reaching the Moon's surface. However, some sunlight still reaches the Moon after passing through Earth's atmosphere, where shorter wavelengths like blue and violet are scattered out, and longer wavelengths such as red and orange are bent or refracted toward the Moon. This refracted light bathes the Moon in a reddish glow. The exact shade of red can vary depending on the amount of dust, clouds, or particles, like from volcanic eruptions, in Earth's atmosphere. This is the same phenomenon—Rayleigh scattering—that causes sunrises and sunsets to appear red.