A blood moon was a dramatic event for early civilisations. Here are some tales from long ago:
Giant Wolves
According to Viking mythology the monstrous wolf Fenrir had two sons, Sköll and Hati. Sköll
would chase the Sun whilst Hati ran after the Moon. If either the Sun or Moon were caught then there was an eclipse.
During an eclipse the Vikings used to try and rescue the Sun or Moon by making as much noise as possible to scare off the giant wolves.
A Substitute King
The ancient Mesopotamians also saw lunar eclipses as an attack on the moon. But in their stories, the assailants were seven demons.
Now the Mesopotamians regarded an attack on the Moon as an assault on their king. But being fairly good at predicting eclipses they could make preparations in advance.
So during the attack they would install someone expendable as a substitute king whilst the real king pretended to be an ordinary citizen. Afterwards the substitute would quietly disappear, possibly by poisoning, and the real king would resume his duties.
A Jaguar
The south American Inca believed that during a lunar eclipse a jaguar attacked the moon and ate it. The feline assault explained why the moon turned blood red.
During lunar eclipses the Inca would shake their spears and beat their dogs. They hoped that this would make enough noise to frighten the big cat away and stop it eating anyone.
Twenty Wives
The Hupa tribe, also in the Americas, believed that the moon had twenty wives and many pets. Most of the pets were mountain lions and snakes. When the moon didn’t bring them enough food they attacked him until he bled. However before long the moon’s wives would come to his rescue and collect his blood to restore him to health. And so the eclipse would end.
What is really going on?
A “blood moon” occurs when the Moon is in total eclipse.
The Moon takes about 27 days to orbit the Earth. Roughly once per month the Moon is directly opposite the Sun. But because the Moon’s orbit is at a slightly different angle to the Earth’s orbit the Earth does not usually get in the way of the sun and we see a full Moon.
However sometimes the orbital plane of the moon lines up with the orbital plane of the Earth and the Earth blocks the sunlight from falling on the Moon. That is what causes a lunar eclipse.
When the sunlight is only partially blocked by the Earth we get a partial eclipse and the Moon darkens slightly. As the eclipse begins a dark shadow can be seen taking a bite out of the edge of the Moon. When the Moon moves directly behind the Earth then we get a total eclipse and the moon goes very dim. The colour turns red because a small amount of light still reaches the lunar surface, refracted through Earth’s atmosphere.
So the red colour of the Blood Moon is the light of every sunrise and sunset on Earth being simultaneously reflected back at us from our Moon.