A conglomeration of confusing moons

At times like this I take solace in my Horace

At times like this I take solace in my Horace. "Indignor quandoquae bonus dormitat Homerus," that writer of the Odes remarked: "I am piqued whenever, now and then, even the good Homer nods". The reason for my rushing to the Odes is an offending paragraph in Weather Eye last Saturday. It said of the full moon expected on the following day "tomorrow's is the last blue moon of the millennium", a message which was faithfully relayed, or so I am told, by Evelyn Cusack on the television. And of course it was no such thing; your diary will confirm for you that another blue moon will occur in March, and - let me risk it - that will be the last blue moon of the millennium.

Normally, as we noted in the offending text, there is only one full moon per month, but since the lunar cycle is a few days shorter than the calendar month, it happens now and then that 13 full moons are squeezed into the same year. The second full moon in a month with two full moons is called a "blue moon". As it happens the event is not all that unusual, and a "blue moon" occurs about every third year, or thereabouts.

What is very unusual indeed, however, is to have two "blue moons" in the one year and it is happening in 1999. After January's double full moon, February will skip a full moon altogether; with only 28 days, it is the only month of the year short enough to be able to accomplish this. February, it seems, last lacked a full moon in 1961, and will miss one again in 2018.

This year, after the event on January 31st, the next full moon will be on March 2nd, and the following one, on March 31st, will provide the second blue moon of 1999. The strange thing is, though, that if I look at my diary here in Germany, it tells me that the two full moons occur in April, and this had me puzzled for a little while.

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The reason, however, is quite simple. March's second full moon occurs at 22.49 GMT on March 31st. By then, however, the clocks will have gone forward so the event will occur at 11 minutes to midnight, Irish time, upon that date. But here in Germany, where I live, the clocks are an hour ahead, so the full moon will occur at 49 minutes past midnight on April 1st. - voila!: the first full moon of two in April, 1999.