Why does the color of the moon turn red during a total lunar eclipse?
From the evening to the night of November 19, 2021 Japan time, a 'partial lunar eclipse close to a total lunar eclipse' that hides 98% of the full moon
Why does the moon turn red during a total lunar eclipse? | Live Science
https://www.livescience.com/33627-moon-red-orange-lunar-eclipse.html
Lunar eclipse is a phenomenon in which the sun, the earth, and the moon line up almost in a straight line around the full moon, blocking the light that hits the moon from the sun, and the shadow of the earth falls on the moon and appears to be partially or totally missing. This is a single image that summarizes the appearance of the moon that can be seen during a total lunar eclipse or almost a total lunar eclipse. When the shadow of the earth falls on the full moon and the glowing part becomes smaller, and finally almost the entire moon is hidden, it looks reddish brown instead of assimilating into the night sky.
If the moon is in the shadow of the earth, it may seem more natural to be painted black and assimilated with the night sky.
Rayleigh scattering is a phenomenon in which when the wavelength of light travels through a medium such as liquid or air, it collides with fine particles that are much smaller than itself and scatters. The sunlight that falls on the earth during the day is scattered by small molecules such as nitrogen and oxygen in the atmosphere and is filtered by a kind.
When sunlight hits the ground from a high angle, the sky looks blue because light with short wavelengths such as blue and purple, which tends to scatter, comes into the eyes more and more. However, at sunrise or sunset when sunlight comes in from a low angle, blue and purple are scattered because the light passes through the atmospheric layer longer than daytime, and this time the wavelength is long and it is difficult to scatter red. It is said that light such as orange and yellow will be easier to see.
During a total or near-total lunar eclipse, it does prevent the Earth from entering between the Sun and the Moon and direct sunlight from hitting the Moon. However, the light is refracted through the atmospheric layer surrounding the outline of the earth, and it is said that it is slightly falling on the moon even during the total lunar eclipse. Therefore, even though the total lunar eclipse is not directly exposed to the sun, the appearance of the moon is vaguely floating in the night sky.
However, since the sunlight that falls at this time passes through the atmospheric layer of the earth, the wavelength of light is scattered by Rayleigh scattering. As with the case where the earth is exposed to sunlight, light such as blue and purple, which have short wavelengths, are scattered before reaching the moon, while light such as red and orange, which are difficult to scatter, reach the moon preferentially. This makes the moon look reddish-brown during a total lunar eclipse or an almost total lunar eclipse.
The color of the moon during a total lunar eclipse also depends on the progress of the lunar eclipse and atmospheric conditions. According to NASA, the moon may appear darker red if large wildfires or ash from volcanic eruptions are floating in the atmosphere.
The partial lunar eclipse that occurs on November 19 is close to the total lunar eclipse, with the largest part of the lunar eclipse being about 98%, and can be observed all over Japan if the weather is favorable. The start of the partial lunar eclipse is around 16:18, the maximum of the eclipse is around 18:03, and the end of the eclipse is around 19:47. The National Astronomical Observatory of Japan is planning to hold a live distribution of the partial lunar eclipse from 16:00 on November 19th to coincide with this astronomical show.
[Live delivery] Partial lunar eclipse (November 19, 2021) | National Astronomical Observatory of Japan (NAOJ)
https://www.nao.ac.jp/news/events/2021/20211101-live.html
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