What is a blood moon?

A blood moon is a type of lunar eclipse where the moon appears to have a reddish hue. This occurs when the Earth is positioned between the sun and the moon, blocking the sun's light and casting a shadow on the moon. During a lunar eclipse, the Earth's atmosphere refracts some of the sunlight passing through it, scattering the shorter blue wavelengths and leaving behind the longer, redder wavelengths. This red light then reflects off the moon, giving it a blood-red or coppery appearance.

It's worth noting that not all lunar eclipses result in a blood moon. The moon's color during an eclipse can vary depending on the amount of dust and clouds in the Earth's atmosphere, as well as the moon's position in its orbit.

Blood moons have been the subject of much fascination and folklore throughout history, with some cultures associating them with omens or supernatural events. Today, however, blood moons are mostly seen as a rare and beautiful astronomical event that can be observed with the naked eye, provided the weather conditions are right.

A blood moon is a popular term for a total lunar eclipse. During a total lunar eclipse, the Earth passes between the Sun and the Moon, blocking all direct sunlight from reaching the Moon. This leaves the Moon completely in shadow, except for a small amount of sunlight that is refracted (bent) by the Earth's atmosphere. The atmosphere scatters blue light more than other colors, so the remaining light that reaches the Moon is red. This is why a total lunar eclipse appears red, or "blood red."

Blood moons are relatively rare events, occurring about once every two years. The next blood moon will be on May 5, 2023.

The term "blood moon" has also been used in a more figurative sense to refer to any time of great turmoil or upheaval. For example, some people have interpreted the tetrad of blood moons that occurred between April 2014 and September 2015 as a sign of impending doom. However, there is no scientific evidence to support this claim.