Let me take you on another short break on our history of the calendar series…

This past week, my Facebook Timeline was flooded with congratulations for Astronomer’s Day (or, in most cases, Astronomy Day), on December 2nd. And as much as I like the attention and all the happy thoughts, I do fell obligated to tell you that this day is far less encompassing than my friends think.

First: it is definitely NOT Astronomy Day. The official name is Astronomer’s Day. And it is not a national celebration. Officially, it is a state celebration, valid in Rio (as far as I know; I haven’t studied the other states’ legislation). It was created by the governor, in Aug. 30, 2006 (state ordinance #4835).

Why December 2nd? It is the birthday of our second (and last) emperor, D. Pedro II. He was an amateur astronomer, and a great enthusiast of Science in general. Under his rule, the Imperial Observatory bloomed here in Rio.

Funny fact: if you Google (in Portuguese) Astronomy Day, you will find several references to April 8, a “International Day of Astronomy”. Funnier fact: the references are in their vast majority all in Portuguese, hinting that this is not a truly “international” thing. And, even worst, I could not find a single trustworthy reference on its origins!

There is, in fact, a “true” international date to celebrate Astronomy (the quotation marks are needed, since this date is not recognized by the IAU or the UN). It is linked to the moon phases, so it is truly an astronomical date!

It was created by the astronomer Doug Berger, when he was president of the North Carolina Astronomical Society, in 1973. He thought it would be a good idea to make Astronomy more popular and, informally, decided to celebrate a Saturday close to the April (or May) First Quarter of the Moon as Astronomy Day.

This idea slowly spread around the world and many countries do that now. Curiously, since 2007, there is a second oficial date, for the Southern Hemisphere, during our own Spring. In 2014, Astronomy Day North was May, 10. Astronomy Day South was October, 4.

Whichever date you pick, the important thing is to keep looking to the sky! ■