Mark your calendar on the 7th of September if you wish to see the 2025 blood moon! While it may sound like something out of a teenage horror film, a blood moon is another name for a total lunar eclipse. The entire lunar eclipse will be visible from beginning till end across Western Australia and Asia. Some phases will also be visible from Africa, Europe, New Zealand, and eastern Australia. These striking total lunar eclipses can only occur during a full moon, when it is on the opposite side of the Earth from the sun. While not regarded as particularly significant astronomically, they are something quite incredible to behold.
What is a Blood Moon?
A full moon usually doesn’t experience an eclipse because it is orbiting in a slightly different plane than the sun and the Earth. Yet, there are certain occasions when these planes coincide and the Earth passes in between the sun and the moon. When this occurs, light from the sun is cut off and the moon is eclipsed. A partial eclipse occurs when only a part of the sun is blocked by the Earth, causing its shadow to fall on the moon. A total eclipse, on the other hand, occurs when the moon is completely in Earth’s shadow. Some of the sunlight is refracted by Earth’s atmosphere and reaches the moon.
This process is called Rayleigh scattering. It is what gives the blood moon its distinctive red color. When light from the sun passes through our planet’s atmosphere, the short violet and blue wavelengths scatter in every direction. However, the red wave lengths are longer and bend around the curvature of the Earth, continuing towards the moon. When fully in the shadow of the Earth, the moon is solely illuminated by this red light.
It’s quite amazing to think that the moon is essentially being illuminated by every sunrise and sunset occurring across the planet at that moment. The specific tone of red will change for every blood moon due to various external factors. If our skies are clear, the moon may take on a soft coppery glow. However, if there is a lot of pollution, volcanic ash, or dust in the air, the moon will take on a brick-red or blood red tone. There are around two to four lunar eclipses every year, and all of them are visible by around half of the Earth. Its one of many celestial events you’ll want to see this year.