Why does moon turn red during lunar eclipse?




Eclipses, whether lunar or solar, have been hot topics for conflicting discussions and superstitions in ancient times. Although the superstitions still prevail in some regions of the world, scientific researches have been able to back up these phenomena with satisfactory logics. Fortunately, a major part of educated global population is well-aware of the events which take place during solar or lunar eclipse and thankfully they believe in science. However, one question remains same for almost everyone: Why does the moon turn red during lunar eclipse?

Reflection of solar light:

There is no surprise in the fact that no planet has the light of its own, they reflect the light of the Sun falling onto them. And so does the mooon. Moon does not have any light of its own but it reflects the sunlight shining on its surface towards Earth. During a total lunar eclipse, earth comes between the sun and the moon, cutting off moon’s supply of light. Resulting in a reddish glow on the surface of the moon rather than becoming completely dark. This has caused many people in the past to refer a total lunar eclipse as “Blood Moon”.

Why the Red Color?

The red colored brilliance of a Blood Moon is due to a phenomenon called the ‘Rayleigh Scattering’. The same mechanism is also responsible for the blue color of the sky and colorful sunsets and sunrises.

There can be a lot of different aspects that can justify the cause of reddish gleam of the Blood Moon. But some of the valid reasons based on facts are:

Colorful Sunlight:

Sunlight may seem white to the human naked eye but it is actually composed of different colors having different wavelengths and specific frequencies. A ray of white light can be split into its colorful components using a prism, just like a rainbow. Colors towards the red band of the spectrum have longer wavelengths and lower frequencies as compared to colors towards the violet part of the spectrum. This can be a major cause of the occurrence of Blood Moon.

The atmosphere of the Earth:

The atmosphere of the earth also plays a vital role in the red colored glow of a moon during the total lunar eclipse. The air surrounding earth is composed of different gases, traces of water droplets and the dust particles, called the atmosphere. When the light entering earth’s atmosphere strikes with such particles which are smaller than the wavelength of light, it gets scattered.

Colors having shorter wavelengths, especially the violet and blue ones, are scattered more strongly and are removed from the sunlight before it hits the surface of the Moon. While the ones with longer wavelengths, like red and orange, pass easily through the atmosphere. This red-orange light is then refracted around the earth, hitting the surface of the Moon and giving it a reddish glow.

Different Shades of Red:

The moon can adopt different shades of red, orange and gold during a lunar eclipse. The number of dust particles, water droplets, clouds, and mist can all easily affect these shades.

Brightness levels:

Scientists measure the brightness level of a total lunar eclipse using a five-mark ‘Danjon Scale’ created by a French astronomer André-Louis Danjon. Ranging from Point 0 to Point 4, a Blood Moon is ranked and given a specific value on the basis of its mid-totality.


Some other factors:

The reddish glow of the moon during a total lunar eclipse depends on many other factors including the earth’s climatic conditions, time of the eclipse, the beginning and the ending of a lunar eclipse.


Blood Moon is Only Moon!

In conclusion, lunar eclipse and Blood Moon are nothing but natural phenomena with logical scientific explanations. There is not much to be afraid or confused about the Blood Moon.  One can only appreciate what nature has created instead of sacrificing it in the name of superstitions.




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