A super blue blood moon is a really… really rare event. A total lunar eclipse coincides with super moon, creating a rare celestial rendezvous that should offer a startling spectacle.
The show promises to be grandiose. A rare celestial rendezvous will mark January 31, when a total lunar eclipse will occur at the time of a blue supermoon. The moon will be closer to Earth, producing what astronomers call the “blue super blood moon”. If the weather conditions are favorable, it will offer on Wednesday a breathtaking spectacle. “We will be able to see, during the eclipse, the reflections on the lunar surface the sunrises and sunsets on Earth,” says Sarah Noble, a NASA scientist. This phenomenon results from a “rare alignment of these three astronomical cycles,” says Jason Aufdenberg, assistant professor of astronomy at the Aeronautical University of Embry-Riddle, Florida.
The term “blue moon” refers to a second full moon in one month, a phenomenon that occurs on average every two and a half years. The eclipse will also occur 27 hours after the moon reaches its orbital point closest to our planet, called the perigee, producing almost a “super moon,” say astronomers. The Moon stands at an average distance of 384 400 kilometers from the Earth and will be on January 31 at 359 000 kilometers, very close to its perigee (356 410 kilometers). At its peak, the lunar orbit reaches 406,000 kilometers. “We have a lot of super moons and lunar eclipses, but these two phenomena do not often coincide with a blue moon,” says Jason Aufdenberg. The last similar celestial rendezvous occurred on December 30, 1982, and was visible in Europe, Africa, and western Asia.
For North America, one must go back to 152 years, to March 31, 1866 and before that to May 31, 1341, according to the annals. Such an eclipse – when the Moon passes into the cone of the shadow produced by the Earth – is also called a blood moon, because the celestial body does not become completely black, a part of the sunlight, reflected by the Earth’s atmosphere, indirectly reaches the lunar surface. Some solar rays are also filtered, which produces a reddish or coppery reflection on the moon. This phenomenon occurs when it is at its orbital perigee. In its orbital extremes, the full moon can appear up to 14% larger and 30% brighter at its perigee than when it is at its peak.
The Super blue blood moon will be observable only in Asia, the Pacific Ocean, Russia, western North America and partially in the east. On the east coast of the United States, the moon will begin to enter the shadow of the Earth Wednesday at 5:51 am, says NASA on its website.
The darkest part of the eclipse, with reddish hues, will be visible from 6:48 am, less than half an hour before sunrise. But observers in the western United States and Canada, where it will still be dark, will be in the best position to observe the eclipse throughout its duration, one hour and sixteen minutes in its entirety. In California, for example, the phenomenon will start at 3:48 am and the total eclipse at 4:51. The best observation period will be between 5 am and 6 am, the complete eclipse phase ending at 6:05 am, according to NASA, which will broadcast the event on its website.
The next super blue blood moon is scheduled for January 31, 2037. But astronomers are eagerly awaiting the total lunar eclipse of January 21, 2019, which will occur around midnight on the east coast and will be visible throughout the United States. During a year, there may be a maximum of four solar eclipses and three lunar eclipses. The use of “blue moon” in reference to this astronomical event “resulted from a blunder in the pages of Sky and Telescope dating back to 1946,” according to Kelly Beatty, a publisher of this American journal.
“The phrase has gone around the world,” he says, attracting the public’s fascination, even giving its name to a cocktail and a beer that is widely sold in the United States. Before that, the formula “ounce in a blue moon” in English described an extremely rare event, specifies the expert. But, he adds, in rare cases, the moon becomes really blue when volcanic eruptions, forest fires or dust storms throw tiny particles into the atmosphere.