Welcome to SkyTours with Derrick! If you've ever found yourself under the night sky wondering what that thing is, well, you've come to the right place to find out. I'll provide regular postings of just what's available for you to see at this time of this year, including planets, stars, constellations and my favorite - satellites! I'll also welcome your suggestions for what to add to the blog for your information and answer your questions.

Thursday, August 22, 2013

There's No Such Thing as A 'Blue Moon'

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!