AUSTIN, Texas - Tuesday night brought the first of 4 lunar eclipses expected this year. 3 of which will be visible from parts of North America.
May’s full moon and a lunar eclipse coincided on May 26 to create a phenomenon known as a "Super Flower Blood Moon."
May’s full moon is referred to as the flower moon, named after the abundance of flowers that emerges in late spring.
The total lunar eclipses are sometimes called blood moons or red moons because of their deep red color, but why does the moon turn red instead of just going darker and becoming a darker gray color?
It’s all down to the earth’s atmosphere. When the earth passes between the moon and the sun the planet will cause a shadow. But the atmosphere is mostly transparent. Mostly. And the atmosphere can act like both a lens and a prism at the same time.
The prismatic effect is the reason why the moon doesn’t go completely dark and becomes a deep reddish hue.
Our atmosphere is mostly nitrogen and oxygen, both of which filter out blue light much more effectively than red light. That’s the reason sunsets are deep reds and oranges. As the sun sets, the sunlight must travel through more and more air, filtering out more and more of the blue light until only red and orange are left.
In the case of the lunar eclipse, the atmosphere is doing the same thing.
All of the light that remains as it passes through the earth’s atmosphere is a deep red color which then reflects off the moon’s bright grey surface.
But wait, the moon is much smaller than the earth. Why doesn’t the earth just block all the light from the sun?
Well, it kind of does, but the atmosphere plays a role in allowing light to get through as well. Our atmosphere is a gas that bends light as it passes through similar to when light bends as it passes through water in a glass. The light is bent around the surface of the earth and angled straight towards the moon.
Less light does hit the exact center of the earth’s shadow, but the combination of so much light that makes it around the earth and the distance the moon is from us makes it basically impossible to notice the difference.
To complete the celestial triple whammy, and explain the mouthful of a name, the eclipse came as the moon was closest to earth, and, hence, a "supermoon."
However, the next total lunar eclipse won’t happen over North America until May 2022.