The Moon’s most dramatic dissappearing act
Celestial events are often hard or impossible to see with the naked eye. As dazzling as images from Pluto or Mars may be, there’s no way we can presently see anything of these planets, outside of a small twinkling light in the sky. Fortunately, the Moon’s proximity to Earth gives us at least one cosmic display that we can all see up close, and tonight’s show will be as big as it gets, literally. While these events were often frightening to people throughout history, it’s absolutely worth the risk to come out and take a look.
Once every 30 years, the orbits of the Sun, Earth and Moon are aligned to create a super-blood-lunar eclipse. While this may sound like a super-hero invented by a 10-year-old, it’s actually three phenomena happening together: A supermoon, a blood moon, and a total lunar eclipse.
A supermoon means that the moon will be closer to Earth than usual. Because neither body has a purely circular orbit, the distance between them can vary, and as we move closer, the moon will appear larger in the sky. Supermoons aren’t too infrequent by themselves, occurring around every 14th full moon.
Blood moons are thanks to the moon reflecting light that has been filtered by the Earth’s atmosphere. As sunlight passes around the edges of the Earth, blue light is scattered by molecules in the air, like the red of a sunset. The atmosphere also acts a bit like a lens, curving the red light around the larger Earth so that it can hit the Moon at all.
The lunar eclipse is what happens when the Moon is finally perfectly aligned behind the Earth, beyond the limits of the light refracted by the atmosphere. Since all the light we see from the Moon is just reflected sunlight, when the Moon passes completely into the Earth’s shadow, we won’t see anything for an hour or so. We’ll then get a bit more blood moon time as it moves back into the sunshine.
No danger for the Moon or Earth
Aside from the infrequency of all three events syncing up, is there any other significance to this? It depends on who you ask. Before modern astronomy, these dramatic events were confusing and often frightful to people around the world, who were suddenly witnessing very unusual shifts in the otherwise reliable sky. Ancient Incas believed the Moon was being eaten by a jaguar during the eclipse, and would make noise to scare it off until the moon was safe (and thus, after a few hours were probably happy to have “saved” the Moon.) Other cultures imagined the shrinking Moon to be under attack from demons, pet mountain lions, or just having a fight with the Sun. In some cases, these events were seen as moments of healing or reconciliation, such as with the Batammaliba people of Togo and Benin. More recently, people have tried to link these kinds of events to earthquakes, beached ships and of course, the end of the world.
Source: Sunday's Lunar Eclipse Has Got It All by Scott Neuman, The Two-Way