In the early morning hours of Wednesday 26 May, the Western United States will be treated to an astronomical event not seen in nearly two and a half years – a total lunar eclipse. The 3-hour and 40-minute event will reach totality over Central Yavapai County at 4:18 AM. The culmination of totality is often referred to as a “Blood Moon” for the deep reddish hue often reflected off the surface of the Moon. This is a result of the Sun’s direct rays being blocked by the Earth, with only a small amount of refracted light passing through Earth’s atmosphere, like light passing through a prism.
A lunar eclipse occurs when the Earth passes directly between the Moon and Sun, essentially forming a straight line, with the Earth’s shadow cast upon the surface of the Moon. Since astronomers love to come up with cool names for astronomical events – usually based on ancient terms of a similar albeit generally terrestrial meaning – this type of alignment is called a syzygy, from the Ancient Greek suzugos meaning “yoked together”. All three bodies gravitationally lined up in space, they are like three oxen abreast to pull a plough. This alignment also means the moon is in its “Full” phase as viewed from Earth, so a lunar eclipse can only occur during a full moon.
Being the brightest full moon was the one to darken, nearly disappear, and then turn a deep red color, ancient cultures often associated the lunar eclipse event as a bad omen. Across continents and millennia, both the Inca and Chinese would attempt to scare away this demonic or evil power by throwing rocks and spears or yelling and the ringing of bells. The Mesopotamians believed seven demons were attacking the sky, followed by the land, and specifically the King. Using a stand-in dressed as the king to fool the would-be usurpers, the eclipse always ended without the predicted celestial battle, and the substitute king was made to disappear – often by poisoning. However, viewing an eclipse as a harbinger of doom is not relegated to the ancient past, as fundamentalist pastors of the last decade predicted a tetrad or set of three eclipses in 2014-15 coinciding with the celebrations of Passover and Sukkot would bring about the rapture.
The Super Blood Moon Eclipse of May 2021 begins Wednesday morning at 1:47 AM when the edge of the Earth’s shadow intercepts the visible surface of the moon, peaking at 4:18 AM, and ends at 5:27 AM. Unlike a solar eclipse, this event lasts much longer and is completely safe to observe with the naked eye. This will also be a “Super Moon”, which may appear larger in the sky as it will be passing through perigee – the point when it is at or near its closest to Earth.
If you normally stay up late, or get up early, or just want to set your alarm, take a few minutes to get out and look up.
The Backyard Astronomer 