Throughout human history, people have looked toward the sky often asking themselves the tougher questions. Questions about themselves, questions about their life, and even questions about what they are seeing. When viewing a total lunar eclipse, the question that may arise is, “why does the moon look like that?” This sight surely had to be frightening to folks from any era before science and technology. 

The Time for Blood

Fortunately, the era of science and technology is happening now and there are answers to the many questions of the past. A total lunar eclipse will take place beginning May 15 and ending May 16. A partial eclipse will start off at 10:15 p.m. May 15. This will lead to the beginning of totality which begins at 11:29 p.m. the same night. The eclipse will conclude shortly after at 12:54 a.m. the next day, May 16. 

Also known as a “Blood Moon”, total lunar eclipses cause the color of the moon to appear red or a rustic orange. This is because of the position that the Sun, Earth, and Moon are in. Lunar eclipses occur when the moon is sitting in Earth’s shadow. This shadow of Earth is caused by the Sun, but it is not a normal shadow. Since the Sun isn’t a point source of light and has dimension it causes two different shadows to appear.

Red Reasons

The “pre” shadow is known as the penumbra. Once the moon begins to move into this area of shadow, we have partial lunar eclipses. The other shadow is deeper into the shade. This area is known as the umbra. When the moon moves into the umbra, that is when totality begins. The umbra itself is about three times the moon’s diameter. 

The deeper reasoning for the Blood Moon’s color change is because of the way light works and Rayleigh scattering. According to NASA, Rayleigh scattering can also be described as the reason we see a blue sky. The way light travels is in waves and each color of light has different properties. Blue light, for instance, has a shorter wavelength than red light. Blue light also scatters more easily through particles in Earth’s atmosphere. Red light travels more directly through. 

Thus, when we see the Sun setting, the sunlight is traveling farther and through more atmosphere. This is why we see the longer-wavelength red, orange, and yellow colors in the sky. When a lunar eclipse occurs, the only sunlight hitting the moon travels through Earth’s atmosphere, traveling farther. This is what makes the moon appear red. In addition, the more dust and clouds that are in the atmosphere at the time of the eclipse, the redder the moon will appear. 

The Lucky Few

There are many planets and moons in our solar system, however, Earth is the only planet that experiences lunar eclipses. The reason for this is that the shadow cast by the Earth is large enough to completely cover the moon. This astronomical event is quite common to us as well.  Lunar eclipses usually occur two to four times a year, according to NASA. The last Blood Moon occurred around the same time last year, May 25-26, 2021.  

There is no special equipment required to see this phenomenon. Only make sure to be looking at the moon between 10 p.m.- 1 a.m. the night of May 15 and into May 16. The Blood Moon must’ve been a nice surprise to the locals in history but for us now it is a delicacy that only our planet enjoys inside this solar system.