Blood moons, which are total lunar eclipses where the moon takes on a reddish hue, typically occur about 2 to 4 times per year
. This happens when the Earth aligns between the sun and the moon, casting its shadow on the moon and filtering sunlight through Earth's atmosphere, which gives the moon a red or orange color
. More specifically:
- Lunar eclipses (blood moons) happen roughly twice a year on average, but the exact number varies between 2 and 4 annually
- Not every lunar eclipse is total; only about one in three lunar eclipses are total, which produce the blood moon effect
- A special phenomenon called a lunar tetrad is when four total lunar eclipses occur in a row over about two years, but these are relatively rare and do not happen every year
In summary, blood moons are not extremely rare but do not happen every month. They occur a few times each year when the moon passes through Earth's shadow during a full moon
