Red Moon Explained: What Causes It and How Rare Is a Blood Moon?

As with all spectacular views, the blood moon is a sight that makes skywatchers curious about the causes, rarity, and behavior of this red moon.

A blood moon is one of nature's many breathtaking views and although it is also a full moon, it does not happen every month. It is also not the usual white round moon observed monthly. Here are some explanations of the red moon which is popularly known as a blood moon.

How is a red moon caused?

When the Sun, Earth, and Moon line up, the Moon enters the Earth's shadow, creating a lunar eclipse. During a total lunar eclipse, the whole moon is engulfed in the umbra, the region of Earth's shadow that is the darkest. The moon will take on a reddish hue when it is inside the umbra. Due to this phenomenon, lunar eclipses are sometimes referred to as "Blood Moons."

During a lunar eclipse, the moon turns red due to Rayleigh scattering, the same phenomenon that causes our skies to be blue and our sunsets to be red. Light moves in waves and each color of light has a unique set of physical characteristics. Because red light has a longer wavelength than blue light, the former is less likely to be scattered or difussed by airborne particles.

Red light, therefore, penetrates the atmosphere more directly.

The sky is illuminated by blue light when the sun is overhead. However, as the sun sets, more atmosphere must be overcome, and the light must travel a greater distance before it reaches the observer's eyes. The sun's blue light diffuses, allowing longer-wavelength light such as red, orange, and yellow to pass through.

During a lunar eclipse, the sunlight that shines on the Moon is turned into a red hue because the atmosphere of the Earth is blocking its path. The moon will emerge redder during the eclipse if there is more dust or cloud cover in Earth's atmosphere. It then appears as if the Moon is being projected with all of the world's sunrises and sunsets, NASA explains.

How rare is a red moon?

The only time a lunar eclipse can occur is during a full moon when the sun fully shines on the moon's surface. An eclipse occurs when Earth blocks the sunlight as it moves between the sun and the moon.

On November 8, 2022, there was a stunning "Beaver Blood Moon," which delighted viewers all over the world. This was the last total lunar eclipse. The next blood moon won't appear until March 13-14, 2025, as per Space.com.

However, although the lunar cycle lasts for only 29.5 days, not all full moons could be blood moons. Royal Museum Greenwich explains that this is due to the moon's orbit being 5 degrees inclined with respect to the orbit of the Earth. This implies that it ascends and descends in its orbit as it revolves around the Earth. This means that the blood moon will only appear in the skies if there is a perfect alignment among the three heavenly bodies.

How long does a blood moon last?

Since the Earth is roughly four times the width of the moon, depending on the circumstances, its shadow can dim the moon for up to five hours. On average, there are two to five lunar eclipses visible from the Earth each year. total lunar eclipses are far rarer depending on the location of the viewer.

During the previous total eclipse, the moon gradually moved into the Earth's "penumbra," before moving into the "umbra," where it remained until it reached its peak.

The total eclipse phase, which peaked at 3 AM and lasted about 90 minutes, was visible on the West Coast of the United States, Reuters reports.