how often is a red moon

A red moon, commonly called a "blood moon," occurs during a total lunar eclipse when the Earth's shadow falls on the moon, giving it a reddish color due to sunlight filtering through Earth's atmosphere. Lunar eclipses, which cause blood moons, occur approximately two to five times per year, but total lunar eclipses (the red moon) happen less frequently, about two every three years on average. From any single location on Earth, a total lunar eclipse can be seen roughly every 2 to 3 years. The reddish color happens because the Earth's atmosphere scatters shorter wavelength light (blue) and allows longer wavelength red light to pass and reach the moon's surface, creating the blood- red appearance. The frequency of visible blood moons varies depending on the location and atmospheric conditions. In summary, a red moon (blood moon) happens during a total lunar eclipse roughly every 2 to 3 years from an individual viewing spot, though lunar eclipses themselves may occur several times annually somewhere on Earth.