Astronomy has many inconsequential and over-hyped terms, such as “blue moon” and “supermoon.” As interesting as they may be, such things are of no consequential scientific value. Even some of the names themselves may not have a scientific origin which explains why an astronomer being asked about them may stare blankly back at you.
At the end of January was a striking example of fake astronomy news. A total lunar eclipse (visible in the western United States) occurred on Wednesday, Jan. 31. However, the headline for an article in the science section of The New York Times said, “Watch the Super Blood Blue Moon Before You Go to Work on Wednesday.” Although the eclipse part of the headline was true, the other elements were questionable.
The claim was made that there was a (1) blue moon, (2) blood moon and (3) supermoon. Let’s examine them one at a time.
The article described a blue moon as “the second full moon to occur in a month.” It doesn’t clearly say it, but it means a calendar month in which there are two full moons. However, this definition is mistaken and has been attributed to an error that appeared in a 1946 article found in one of the precursors of the venerable Sky & Telescope magazine. This error was finally corrected decades later in a 1999 Sky and Telescope article.
The discovery of the error as well as the correct definition of blue moon was apparently newsworthy enough to get reported in a New York Times article on April 1, 1999. It said that the original and correct definition of a blue moon is “understood to be a fourth full moon in a season, which normally has three.”
There are two full moons in January and two in March of 2018, on the 2nd and 31st of both months. However, the latter one in March occurs after the Vernal Equinox — the start of spring. So even though both months have two full moons, none are blue moons. That is because this winter there are only three full moons during the season: the two in January and the first one in March. There is no blue moon anytime this winter. As a matter of fact, 2018 has no blue moons at all!
Thus, although the original erroneous definition of blue moon was first made more than seven decades ago, and The New York Times reported both the error and the correction nearly two decades ago, The New York Times was once again repeating wrong information less than one week ago.
Next, The New York Times describes a blood moon as something that “occurs as the moon slides behind Earth’s shadow during a lunar eclipse.” I had never heard a lunar eclipse described as a blood moon until a couple of years ago, so where did the term originate?
In February last year, Bruce McClure, a writer for EarthSky.com wrote that the term blood moon “appears to have been popularized by two Christian pastors, Mark Blitz and John Hagee. They used the term to apply to the full moons of the 2014-2015 lunar tetrad — four successive total lunar eclipses, each separated by six lunar months, with no partial lunar eclipses in between.”
So, the actual definition of the recently coined blood moon is four consecutive total lunar eclipses. Not sure if it means all four eclipses or only the last one. But that doesn’t matter, because the previous lunar eclipse that occurred in August was partial, not total.
What about going forward? Was the January eclipse the first of four consecutive total lunar eclipses? No. There will be two in 2018 and one in 2019, but the fourth is a partial eclipse, not a total. Thus, the January eclipse was not a blood moon. Once again, The New York Times got it wrong.
Finally, what’s this “supermoon” business all about and where did the term originate? That’s another expression I never heard until asked about by friends. According to “Bad Astronomer” Bill Platt writing in Slate magazine, supermoon is “not a real astronomical term — it was actually coined by an astrologer,” so it’s no wonder I’d never heard of it previously.
According to The New York Times, a supermoon simply means “it will be closer to the Earth than usual,” a more or less mealy mouthed description. If they simply mean that a supermoon is closer to the Earth than average it’s hardly unusual or worth reporting as the moon will spend roughly equal times closer as it does farther than average.
I suspect that The New York Times has got the supermoon description wrong or at least imprecise to be more generous. In previous supermoon reports media sources will mention that the full moon coincides with perihelion — the closest distance between Earth and moon — 225,740 miles (363,293 kilometers). That would, indeed, be a fairly rare, though hardly remarkable, event to the naked eye.
Other modern sources dignify the word supermoon with a more precise definition of a full moon where the center-to-center distance between Earth and moon is 224,000 miles (361,000 kilometers). According to this definition, the full moons of January 2018 were both supermoons.
In this summary of fake news in astronomy, The New York Times published two erroneous facts (blue moon and blood moon) and one imprecise definition (supermoon) in a single article.
The New York Times is not alone in making these kinds of mistakes. Many news outlets and web sites purporting to be sources of science information frequently pick up and copy each other’s errors and inaccuracies.
Speaking of full moons, something unusual is happening this month that is not only rare, but as far as I know doesn’t have a name given to it by either astronomers or astrologers.
February 2018 does not have a full moon. Fortunately, bookends January and March make up for it with their two full moons each.
To conclude, the essential thing to keep it mind is stimulating curiosity is important. It’s not as simple as the ends justifying the means, but even bad science can have a silver lining if it motivates people to go outside and look up.