As May comes to an end, a rare astronomical event will occur, the Super Blood Moon. Let’s learn about this event with three simple questions.
1. What is a Super Blood Moon?
A Super Blood Moon is an amalgamation of two lunar events: a supermoon and a total lunar eclipse. The Moon’s orbit around the Earth isn’t perfectly circular. It’s an elliptical (egg-shaped) orbit. Because of that, the distance between the Earth and the Moon keeps changing. The point of the closest approach is known as perigee. The farthest point, on the other hand, is called apogee. The Moon takes approximately 27 days to orbit the Earth, changing its phase each day.
When the Moon reaches its full phase (the Full Moon) at (or around) its perigee, we call it a supermoon. If it’s on the apogee, we refer to it as the micromoon. According to NASA/JPL, at its largest, it can appear 14% larger in diameter and 30% brighter than the smallest full moon.
If the date of the total lunar eclipse coincides with a supermoon, we get to see a Super Blood Moon. It’s a sporadic event. Out of a dozen annual full moons, about a couple happen to be supermoons. On average, a total lunar eclipse can be seen from any given location every 2.5 years. Hence, the occurrence of a supermoon and a total lunar eclipse is rare.
2. When is the Super Blood Moon, and how can you see it?
In 2021, a Super Blood Moon will appear on 26 May. The Moon will pass through the Earth’s shadow between 09:45 UTC and 12:52 UTC, creating a total lunar eclipse. The eclipse will be visible from any location where the Moon is above the horizon at the time, including from Oceania, the Americas, and Eastern and Southeast Asia. A detailed map of the eclipse is given below:
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3. Why is it called a Blood Moon?
No! It has nothing to do with the devil, and neither is it any supernatural phenomenon. It’s simple physics. During a total lunar eclipse, the only sunlight that reaches the Moon’s surface is the one refracted from our atmosphere. Because of the alignment of the three celestial bodies, the sun rays have to travel a longer distance in the Earth’s atmosphere before they reach the Moon. The white light coming from the Sun is composed of different colors (VIBGYOR) having a different wavelength. According to the Rayleigh scattering phenomenon, light waves with shorter wavelengths are scattered more than waves with longer wavelengths.
Hence, as the white light composed of different colors travels through the Earth’s atmosphere, shorter wavelengths such as blue and green are scattered. In contrast, the longer ones, such as orange and red, are filtered out and hit the Moon’s surface. Hence, the Moon appears red during a total lunar eclipse. It’s because of the same phenomenon that the rising and the setting sun appears red.
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