A blood moon, which is a total lunar eclipse where the moon takes on a reddish hue, typically occurs about two to four times per year overall. However, total lunar eclipses visible from any given location happen less frequently, roughly two every three years. The "blood moon" effect happens when Earth’s shadow completely covers the moon, causing sunlight filtered through Earth's atmosphere to cast a red glow on the moon. Lunar eclipses happen about two to five times a year globally, but not all are total eclipses or appear as blood moons. Lunar tetrads, which are sequences of four total lunar eclipses in about two years, are rare and happen irregularly over centuries. In summary:
- Lunar eclipses occur 2 to 5 times a year globally.
- Total lunar eclipses, which cause the blood moon phenomenon, happen about 2 every 3 years.
- Blood moons (total lunar eclipses with the reddish color) can be seen a few times a year somewhere on Earth.
- Lunar tetrads (four blood moons in two years) are rare and occur irregularly over centuries.
