What is a Blood Moon?

A blood moon is a lunar eclipse where the face of the moon turns a deep, dark red because of the way the light from the sun is filtered through the Earth’s atmosphere. This type of phenomenon is not something that happens all the time, but instead occurs only in certain circumstances, and the conditions have to be just right for the blood moon to become visible.

Why is a Blood Moon Red?

A blood moon happens during a total lunar eclipse, when the Earth moves directly between the Sun and the Moon and blocks the Sun’s direct sunlight from reaching the Moon. Since there is no direct sunlight to light up the Moon’s surface, the light that does reach the Moon is a combination of light which has passed through Earth’s atmosphere and has been refracted by atmospheric particles. Those atmospheric particles filter out the blue light from the Sun’s rays, considered to be the shortest wavelength in the visible spectrum. The remaining light consists of the longer wavelength of red light, which is why the Moon appears to take on a red hue during this phenomenon.

What is Super Blood Moon?

Super blood moon is derived from the combination of two separate celestial events. A Super Moon is when the Moon is full, and happens at the same time for all locations on Earth, although the exact time does vary depending on your location. When the Moon is at its closest point to Earth in its elliptical orbit, it will appear larger and brighter in the night sky than usual, which is why it is referred to as a Super Moon. The second half of the Super Blood Moon term is derived from the fact that it will also coincide with a total lunar eclipse, and because of the combined effect of both events, the Moon will appear to be an even deeper hue of red than usual.

It is because of this unique combination of events that the phenomenon is referred to as a “Super Blood Moon,” and this is the only time it can be seen. As of June 2020, the last Super Blood Moon was on 21 January 2019, so if you missed that one, don’t worry, because the next one is due to arrive on 31 May 2021.