Despite the success of The Marcels' 1961 doo-wop hit, I have to bring you the bad news that there is no such thing as a 'blue moon' - at least not in this solar system. Did you see ‘the’ blue moon
last Tuesday? Have you ever seen a blue moon? I didn’t see ‘the’ blue moon’ on
Tuesday because there wasn’t one. Have I seen a blue moon ever? No, because the
moon cannot be blue. If you’re wondering what all this claptrap is about, as it turns out, Tuesday's
full moon was NOT a blue moon, neither in the 'traditional' sense or literally, even though several national news outlets described it as one.
Unfortunately, what we all describe
as a 'blue moon' is a clash between folklore and science. The traditional 'blue
moon' that most of us refer to is the instance when there are two full moons in
one month. Happens every 2.7 years on average and here's how to think about it:
Given that there's a full
moon every month, there should be 12 full moons in a year and therefore 3 full
moons in each season (3 for spring, 3 for summer, 3 for fall, 3 for winter).
Occasionally, due to calendrical quirks, there can be 4 fulls in one season
and in some folklore, the third of the four is called a 'blue moon'. This
'definition' hasn't been current or contemporary for many, many years. In
recent folklore (actually the mis-translation of someone else's definition of
the phenomenon!) , a 'blue moon' is defined as the second full moon in a month
and Tuesday's full moon DID NOT satisfy the required criteria for 'blueness'
according to modern popular folklore.
Now, how did this false 'blue moon' get into
the popular press, you may ask? Newsroom researchers, armed with access to the
World Wide Web can search up all manner of obscure trivia to fill the massive amounts
of on-air time the news programs have strapped themselves with. Some
well-meaning but astronomically challenged researcher found this trivia point
and with no one on their staff to properly vet this, they RAN with it! It's not even a
scientific phenomenon. The so-called 'blue moon' is a result of our civil
calendar trying to trap the eternal motions of the moon into a limited
framework. The moon doesn't care about months or seasons – it just orbits the
Earth. End of story. We humans add the rest.
The photo of the blue moon
was FAKED – either by coloring the moon blue with some graphic image tool or an
actual photo of the moon, seen as blue because of some completely unrelated
atmospheric effect (like volcanic dust aerosols or forest fire smoke particles)
allowed the moon to be seen as blue and THAT image was connected to the 'blue
moon' story. This is an excellent 'teachable moment' about how access to
information does not make one an expert or how NOT to use the Internet.
Another example of
overzealous Web searching is the announcing of inconsequential meteor showers
like the Delta Aquarids in July, with an hourly rate of 16 meteors per hour. On
any given night, anyone almost anywhere can see 10 meteors per hour, so seeing
six more per hour is not worth announcing as 'nature's celestial fireworks'.
BTW 16 per hour is one every 3.75 minutes – one of the better examples of the
phrase 'about as exciting as watching paint dry'. Even the best showers of the
year only average a meteor every 30 seconds – and that’s average! Sometimes we
can see a flurry of meteors or a bright fireball occasionally, more often it
can be minutes between faint, short, unspectacular streaks. Hardly celestial
fireworks.
But meteors showers are to
be noted if you happen to be out on the night of peak ‘shower’ activity. Unless
you’re out to view the November Leonid shower at one of its 33-year maximums,
don’t make a meteor shower the focus of your observing session. Use it as an
added treat to being outside at night, enjoying a casual look at the heavens.
And by all means, DON’T get up at 2 a.m. to see a meteor shower. If you’re an
insomniac or raiding the refrigerator because you just can’t get that last
slice of cherry cheesecake out of you mind, have a look to see what’s
happening.
Sound like astronomy
observing blasphemy to discourage observing? Not at all, just helping casual
observers, like most folks, focus energy
and interest to the real exciting sights, like Comet ISON coming later this
year. That'll be worth getting up in the middle of the night!
