In the night between July 27th and 28th, people living in the eastern hemisphere will be able to see a blood moon. Apart from this, skygazers will get another exclusive view, namely the longest lunar eclipse of the century. Unfortunately, the phenomenon won’t be visible for people in the US.
What is a blood moon?
A blood moon appears whenever a full moon looks bigger and brighter than usual. In most cases, it also acquires a reddish hue, thus the name of blood moon. However, such a phenomenon is not possible without a lunar eclipse, as this overshadowing is the one that gives the moon this strange color.
During an eclipse, the moon, the sun, and our planet are perfectly aligned. A lunar eclipse occurs whenever Earth falls right between the two, blocking the sunlight from reaching the moon. This alignment also makes possible the phenomenon that gives the moon its color.
Why does the moon appear red during a lunar eclipse?
Therefore, the blood moon appears red because of Rayleigh scattering. Since Earth is placed right in front of the moon, the sunlight first has to pass next to our planet. When this happens, it gets filtered through the atmosphere, highlighting certain shades in the spectrum.
Also, all the elements present in our atmosphere, such as pollution or dust, influence the shade of the blood moon. Dust and other thicker elements stop the blue waves in the light, but the red ones are stronger. Therefore, they are the only ones that reach the moon.
However, this lunar eclipse will be different. It will be the longest in the century, as several factors coincide and make it possible. When the moon is in its furthest point from Earth, it will also fall in the darkest part of its shadow. The blood moon is also the smallest of the year, which means it takes more time to get out of the shadow. As a result, we get the longest lunar eclipse of last 100 years.
Image source: Pixabay