Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Blue Moon 2012 – Except parts of Oceanea


Tonight is a Blue Moon and a Friday the Dyslexic 13th Full Moon.

As conspiracy theorists say, That can’t be a coincidence!

Of course it can be a coincidence.

The next Blue Moon is in 2015, unless you are near the International Date Line, in which case the Blue Moon is not this month, but at the end of next month (and then in 2015).[1]

Click on images to make them larger.

Does anything special happen during a Blue Moon?

There is more light, but they are really only uncommon.

The full moon does not have an influence on our lives, except to annoy the superstitious, to provide more light, and to give me another reason to throw some light on the lunacy of full moon superstition.

Image credit.

“Have you university types ever looked at whether dog bites happen more around the full moon? It’s a well known fact that they do.”[2]

They could accept the old farmer’s tale or they could examine it. It appears that even though the farmer seems to be set in his belief, he is still open to evidence.

The influence of the full moon remains one of the more resilient popular explanations of a wide range of mostly traumatic or bizarre events. There is a pale reflection of this in epidemiology—recall bias—where those affected by a rare or severe disease are more inclined to associate unrelated non-disease exposures to the disease.[2]

This is a lighthearted look at the numbers of admissions for dog bites and whether there is any association with the full moon.

The beginning of the dates is the first full moon, although it is not marked. There is no peak at the beginning of the chart, so this was not done to mislead. It might be because there were so many days with very few dog bite admissions at that full moon.

Altogether 1671 accident and emergency admissions for dog bites occurred during the study period (938 males, 733 females), representing an overall mean admission rate of 4.58 per day. Figure 1 shows 18 peak days (notionally >10 admissions/day), with the maximum peak centring on the New Year break (the highest peak (24) occurred on New Year’s Day 1998). Full moons coincided with none of these peaks.

There were 12 full moons, but none of the excessive dog bite days were at the time of any of the full moons.


If there is any causal relationship between the full moon and serious dog bites, the occurrence of the peaks should be greater than predicted by chance.

By my calculation, there is just over a 64% chance of any of these 18 peak dog bite days and any of the full moons occurring together by chance in that one year period. A longer time period would be better for making this clear, but there does not appear to be any suggestion of any association between full moons and admissions for dog bites.

Overall, full moon days were associated with slightly lower mean admissions (4.6 compared with 4.8 per day).[2]

During the study, there were fewer serious dog bites during the full moon, than at other times.

As the plot of dog bite admissions and full moons clearly shows, more caution with dogs might be exercised over Christmas and especially at New Year—irrespective of the full moon.[2]

It may not be a good idea to try to make friends with strange dogs on those days.

Correction (8/21/2013 20:08) – Here is an article that shows I was wrong about the two full moons in a month definition of a full moon.

What’s a Blue Moon?
The trendy definition of “blue Moon” as the second full Moon in a month is a mistake.

Sky & Telescope
by Donald W. Olson, Richard Tresch Fienberg, and Roger Sinnott
July 27, 2006


[1] How often do two full moons happen in the same month?
Friday, August 31

[2] Barking mad? another lunatic hypothesis bites the dust.
Chapman S, Morrell S.
BMJ. 2000 Dec 23-30;321(7276):1561-3.
PMID: 11124174 [PubMed – indexed for MEDLINE]

Free Full Text from BMJ

Chapman S, & Morrell S (2000). Barking mad? another lunatic hypothesis bites the dust. BMJ (Clinical research ed.), 321 (7276), 1561-3 PMID: 11124174



  1. “The full moon does not have an influence on our lives, except to annoy the superstitious, to provide more light, and to give me another reason to throw some light on the lunacy of full moon superstition.”

    Besides causing literal astronomical changes in tidal flow that results in unusual flooding, damage to boats, docks and houses…

  2. Bravo, Bravo and thank you for that one. I am working the 4-12 shift tonight because my employer cannot prove we need no extra coverage and his exact quote: “We always have more calls on a full moon.”

    Funny, I thought the most calls were usually at the first week of the month right after the government had handed out its social assistance checks and people are usually “loaded.”I fully anticipate a shift of very few calls.

    I guess I’ll listen to the Needle Decompression podcast and chalk it up as CE since I am going to getting a lot of down time.

    Thanks again and take care


  3. I found that very interesting that there were more dog bites at Christmas and New Year. I wonder why that is? Dogs not feeling very festive? Maybe people are more likely to be drunk at these times and this affects their behaviour towards dogs, e.g. teasing them incautiously, getting over friendly with strange dogs. Or maybe, even worse, people are giving alcohol to poor dogs and they become aggressive as a result.