Super Blood Moon, May 26, 2021 : Science and Myths Behind
Super Blood Moon 2021 Myths & Science Behind
This month brings the “most super” of the year’s supermoons, and on top of that, a total lunar eclipse. In other words, on May 26, 2021, the full moon will enter Earth’s shadow — and, when the Moon is not in our planet’s shade, it will appear even bigger and brighter than usual.
What is a supermoon?
The Moon travels around our planet in an elliptical orbit, or an elongated circle. Each month, the Moon passes through perigee (the point closest to Earth) and apogee (the point farthest from Earth). When the Moon is at or near its closest point to Earth at the same time as it is full, it is called a “supermoon.” During this event, because the full moon is a little bit closer to us than usual, it appears especially large and bright in the sky.
What is a lunar eclipse?
A lunar eclipse takes place when the Sun and Moon occupy precise positions on opposite sides of Earth. During this alignment, Earth blocks some of the Sun’s light from reaching the full moon. Our atmosphere filters the light as it passes, softening the edge of our planet’s shadow and giving the Moon a deep, rosy glow.
How can I see the supermoon eclipse?
Observers all over the world will be able to see the supermoon throughout the night if the sky is clear. Like all full moons, the supermoon rises in the east around sunset and sets in the west around sunrise. It is highest overhead in the late night and very early morning hours.
The lunar eclipse is harder to catch. The total eclipse, or the time when the Moon is in deepest shadow, will last for about 15 minutes. If the Moon is up in your area while this happens, you are in for a treat.
The total lunar eclipse will be visible near moonset in the western continental United States and Canada, all of Mexico, most of Central America and Ecuador, western Peru, and southern Chile and Argentina. Along the Asian Pacific Rim, the total eclipse will be visible just after moonrise.
The partial eclipse, which takes place as the Moon moves into and out of Earth’s shadow, will be visible from the eastern United States and Canada just before the Moon sets in the morning, and from India, Nepal, western China, Mongolia, and eastern Russia just after the Moon rises in the evening.
Observers in eastern Australia, New Zealand, and the Pacific Islands, including Hawaii, will see both the total and the partial eclipse.
If the supermoon eclipse isn’t visible from your location, you can still explore this phenomenon second by second with NASA’s Scientific Visualization Studio.
Why does the Moon turn red during a lunar eclipse?
Colors are one way for our brains to interpret variations in the physical properties of light. These same properties cause each color of light to behave differently when passing through a substance like air. If you’ve ever looked up at a blue sky, or savored a fiery sunset, you have seen this phenomenon in action.
Sunlight bends and scatters as it passes through Earth’s atmosphere. In air, colors at the blue and violet end of the rainbow scatter more widely than colors like red and orange. Widely scattered blue light tints the sky when the Sun is overhead on clear days. Redder light travels a straighter path through the air; we only see it scattered throughout the sky around sunrise and sunset, when sunlight has traveled through a thick slice of Earth’s atmosphere before reaching our eyes.
During a lunar eclipse, some of this heavily filtered morning and evening light makes it all the way through Earth’s atmosphere and eventually reaches the lunar surface. The eclipsed Moon is dimly illuminated by red-orange light left over from all of the sunsets and sunrises occurring around the world at that time. The more dust or clouds in Earth’s atmosphere during the eclipse, the redder the Moon will appear.
Are all supermoons red? Are all lunar eclipses supermoons?
No, and no. Supermoons and lunar eclipses are different phenomena that do not always occur at the same time. This month brings an excellent opportunity to enjoy the view.
Marauding demons, murderous pets, and ravenous jaguars are just some of the culprits that cultures around the world have blamed for the moon's disappearance during lunar eclipses.
During the night of April 14 through April 15, the first total lunar eclipse in more than two years will be visible across North and South America, and from Hawaii. (See "Viewing Guide: Watch Moon Turn Red During Total Lunar Eclipse.")
While such celestial events are celebrated today with viewing parties, road trips, and astronomy talks, eclipses haven't always been events that people looked forward to.
Many ancient cultures saw solar or lunar eclipses as a challenge to the normal order of things, says E. C. Krupp, director of the Griffith Observatory in Los Angeles, California. "Things that shouldn't be happening are happening." (See "Solar Eclipse Myths From Around the World.")
Howling at the Moon
"[The Inca] didn't see eclipses as being anything at all good," says David Dearborn, a researcher at the Lawrence Livermore National Laboratory in California, who has written extensively on how the Inca viewed astronomy. Accounts written by Spanish settlers in the New World record the Incan practices surrounding eclipses, he says.
Among the collected myths is a story about a jaguar that attacked and ate the moon. The big cat's assault explained the rusty or blood-red color that the moon often turned during a total lunar eclipse. (See "Lunar Eclipse Pictures: When the Moon Goes Red.")
The Inca feared that after it attacked the moon, the jaguar would crash to Earth to eat people, Dearborn says. To prevent that, they would try to drive the predator away by shaking spears at the moon and making a lot of noise, including beating their dogs to make them howl and bark. (Read about the Inca Empire in National Geographic magazine.)
A Substitute King
The ancient Mesopotamians also saw lunar eclipses as an assault on the moon, says Krupp. But in their stories, the assailants were seven demons.
Traditional cultures linked what happened in the sky to circumstances on Earth, he says. And because the king represented the land in Mesopotamian culture, the people viewed a lunar eclipse as an assault on their king. "We know from written records [that Mesopotamians] had a reasonable ability to predict lunar eclipses," says Krupp. So in anticipation of an eclipse, they would install a surrogate king intended to bear the brunt of any attack.
"Typically, the person declared to be king would be someone expendable," Krupp says. Though the substitute wasn't really in charge, he would be treated well during the eclipse period, while the actual king masqueraded as an ordinary citizen. Once the eclipse passed, "as you might expect, the substitute kings typically disappeared," Krupp says, and may have been dispatched by poisoning.
Healing the Moon
The eclipse myth told by the Hupa, a Native American tribe from northern California, has a happier ending.
The Hupa believed the moon had 20 wives and a lot of pets, says Krupp. Most of those pets were mountain lions and snakes, and when the moon didn't bring them enough food to eat, they attacked and made him bleed. The eclipse would end when the moon's wives would come in to protect him, collecting his blood and restoring him to health, Krupp says.
To the Luiseño tribe of southern California, an eclipse signaled that the moon was ill, says Krupp. It was tribe members' job to sing chants or prayers to bring it back to health.
Modern Myths
Not all cultures view an eclipse as a bad thing, says Jarita Holbrook, a cultural astronomer at the University of the Western Cape in Bellville, South Africa, in an interview last year.
"My favorite myth is from the Batammaliba people in Togo and Benin" in Africa, she says. In this myth, the sun and the moon are fighting during an eclipse, and the people encourage them to stop. "They see it as a time of coming together and resolving old feuds and anger," Holbrook says. "It's a myth that has held to this day."
Ancient rituals will mingle with contemporary science as the Griffith Observatory marks the April 14-15 eclipse. "Based on past experience, we expect a very large crowd to show up," Krupp says, as staff and astronomers gather on the Los Angeles observatory's front lawn with telescopes—and with noisemakers.
"If there's a celestial object threatened, Griffith Observatory is in the business of protecting and observing," Krupp says with mock gravity. He plans to don his "official eclipse-dispersing wizard's robe and hat" and lead marchers around the lawn with noisemakers, to scare off whatever is swallowing the moon.
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