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The Ides of October

October 15, 2012

October fifteenth may not appear to be an exciting date, but October 15, 1582, was an exciting day. October 15, 1582, was the first day of the Gregorian calendar, named after Pope Gregory XIII. Gregory realized that a revision of the Julian calendar, a remnant of Roman times, was in order. The Gregorian calendar is the presently used civil calendar for the United States and most of the world.

The Gregorian calendar was a big change in 1582, since October 4, 1582, was followed by October 15, 1582. Some of the populace were worried that they were actually losing ten days of their lives. That's another reason why public education is important today.

Astronomers still prefer using the Julian date, a day count from noon, GMT, on January 1, 4713 BC. Today is Julian day 2456216, starting at noon. Astronomically, starting things at noon makes a lot of sense, since that's when optical astronomers, at least those living near Greenwich, England, are still in bed. Spreadsheets use a similar dating idea, usually keeping track of fractional days since midnight December 31, 1899.

There are a few notable people born on this date in the post-Gregorian calendar period. German philosopher, Friedrich Nietzsche, was born on this date in 1844; economist, John Kenneth Galbraith, in 1908; and automotive executive, Lee Iacocca, in 1924. This is also the supposed birth date of the Roman poet, Virgil (Publius Vergilius Maro), who was born in 70 BC, before the Gregorian calendar.

I write, "supposed," since the evidence that places Virgil's birthday on our October 15 is not that great. The first clue is the names of the months. September, October, November and December were the seventh, eighth, ninth and tenth months, not months 9-12 as they are today. Also, Virgil's recorded birthday is not an actual date, but rather the Ides of October. This is generally taken as the fifteenth of October, but I'm sure there was always a rounding, up or down, when it came to a birthday in those days, to make things easier to remember.

I mention Virgil because of his appearance in Dante's Inferno.[1-3] In that book, Virgil is Dante's guide to the Underworld, and he introduces Dante to some of the STEM celebrities of antiquity. These were Avicenna, who wrote books on mathematics and many of the sciences; Euclid, who needs no introduction; Pedanius Dioscorides, who wrote an important pharmacopeia; and Hippocrates.

Virgil, Dante and the boatman, Phlegyas
Virgil and Dante crossing the Styx in Phlegyas' boat. Detail of an illustration by Gustave Doré from Dante's Inferno. (Via Wikimedia Commons).

So, which famous scientists have an October 15 birthday? There are four who are considered important enough to command a Wikipedia entry.
• Evangelista Torricelli (1608), the Italian physicist who invented the barometer.

• Asaph Hall (1829), American astronomer who discovered Deimos and Phobos, the moons of Mars.

• Malcolm Ross (1919), atmospheric physicist and balloonist.

• Peter Doherty (1940), Australian immunologist and Nobel laureate, noted for his work on the major histocompatibility complex.
Mars moon PhobosA moon with personality.

Asaph Hall would never have expected Phobos to be so unlike a sphere when he discovered the moons of Mars in August, 1877.

(Mars Reconnaissance Orbiter photograph, via Wikimedia Commons).

These four scientists are on a list of 185 famous people with an October 15 birthday. Four scientists out of 185 is just 2.1%. The rest of the list is replete with entertainers and athletes. You can clearly see where the values of the populace lay, although one mitigating effect might be that scientists are generally famous only when they're old. The other professions favor the young, so there will be more such entries. You might call this the Bieber effect.

Of course, one data point is just anecdotal evidence, which does not satisfy a scientist. I checked October 14 (6/204 = 2.9%) and October 16 (2/180 = 1.1%). The October 16 figure might be inflated, since one of the scientists (engineer, María Eugenia Larraín) is there because of her career as a model. I've always considered engineers to be fellow scientists. At the Ph.D. level, especially, there's no real difference.


  1. La Divina Commedia di Dante: Inferno by Dante Alighieri (Italian version), Project Gutenberg.
  2. Divine Comedy: Hell by Dante Alighieri, Longfellow's Translation, Project Gutenberg.
  3. Divine Comedy: Hell by Dante Alighieri, Translation by Henry Francis Cary, with Gustave Doré illustrations, Project Gutenberg.

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