Bloodmoon

The Moon existed before the first animals lived on Earth and even before the first cells divided. From the dinosaurs living more than 66 to 245 million years ago to now us living in the 21st century, we have always been looking at the same Moon. People have been using it as an astronomical calendar in the sky by indicating the Moon phase for thousands of years. It must have been terrifying when they saw that the bright and serene Moon had turned into a red and bloody Moon. Nowadays, we know this phenomenon as a lunar eclipse, also called the Blood Moon.

Firstly, I will tell you more about the positions of the Sun, the Earth and the Moon. Like all the planets in our solar system, the Earth orbits the Sun. It takes the Earth 365 days to make a circle around the Sun. At the same time, the Moon orbits the Earth which takes approximately 27 days. Every day the shape of the moon is different. This depends on the location of the Moon around the Earth and which part of the Moon is therefore illuminated by the Sun

During a ‘normal’ full Moon, the Earth is located between the Moon and the Sun. However, if the Moon, the Earth and the Sun would be in a straight line, the Earth would block all the Moon’s sunlight. If that were to happen, you would think that you wouldn’t be able to see the moon at all. However, this doesn’t happen because the Moon’s orbit is tilted by a few degrees relative to our path around the Sun. Therefore, the Moon, the Earth and the Sun are not in a straight line, and the Earth isn’t in the way of the Moon’s sunlight.

Nevertheless, twice a year, the Moon, the Earth and the Sun are in a straight line. As I said before, you would think that you would not be able to see the Moon because the Earth is blocking all the sunlight from the Moon, but that is not the case, and I will tell you why.

The wider outer shadow, where the Earth is only partially blocking the sun’s light, is called the penumbra. The moon barely dims when it moves through this area. The umbra is the name for the middle, narrow shadow when Earth completely blocks the sun’s light. When the moon is completely in the Earth’s umbra, something strange happens:

A small part of the sun’s light passes through our atmosphere and comes out on the other side in the shape of a ring-shaped lens. During this process, the air in our atmosphere filters short wavelengths from the sunlight out. This means that only bigger wavelengths are left and all the warmer colours that come close to red have bigger wavelengths than the other colours. This is the reason why the Moon turns red. Interesting fact: The reason for sunsets and sunrises appearing red here on Earth is the exact same one.

Now, that we know how the Blood Moon is formed, it may spoil its beauty for you. However, believe me when I say that there is an even greater beauty in understanding the science behind one of nature’s most breathtaking performances. So if you’re ever lucky enough to see a Blood Moon in real life, just take a moment to contemplate on how truly marvellous and impressive the universe is.

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