David Fabricius
Published on Mar 9, 2008 at 2:07 pm.
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Filed under astronomers, history.
There is a crater on the Moon named Fabricius. It is about 2.5 kilometers deep and 78 kilometers in diameter. According to a NASA list of crater names, it is named for the astronomer David Goldschmidt. Who is the Goldschmidt, and why is the crater named for him? I chose to write about him today because he was born on this date, March 9, in the year 1564.
As it turns out, Francisco Bergali explains, Fabricius is the Latinized version of his name (though I am not sure how you get from Goldschmidt to Fabricius). David Goldschmidt (David Fabricius) was a Lutheran pastor and an amateur astronomer. At any rate, the name David Fabricius is known to me because I am a variable star astronomer. Fabricius is credited with the modern discovery of variable stars, with his finding that the star Mira is variable. Actually, the name Mira was given to the star almost a half century after Fabricius’ discovery by Johannes Hevelius. Fabricius simply noted that there was an extra star near Aries (actually in Cetus) in 1596. He wrote to the famous astronomer Tycho Brahe with his finding. At the time, Fabricius didn’t know what to make of his discovery. He thought that this was a nova, or a new star that sometimes appears in a constellation for a period of time (we now know that a nova is the result of a runaway nuclear reaction on the surface of a white dwarf).
Fabricius’ star was designated Omicron Ceti by Johann Bayer. Fabricius, though, observed the star again in 1609. This time, he knew that he’d found something odd, because no one at that time had heard of a recurrent nova (now we know that that can happen, too). So, he knew that this was a very special star of some sort. By this time, Tycho Brahe had died, so he corresponded with Tycho’s successor, Johannes Kepler.
Two years later, in 1611, Fabricius’ son, Johannes, returned from university with a telescope. Together they began exploring the heavens with their new tool. They observed sunspots and saw that they moved across the face of the Sun with time. This led them to conclude that the Sun rotated. That was not a new finding, having been already been reported by Galileo Galilei and others. However, it was important for other astronomers to confirm the earlier findings. That was particularly important at the time because the Sun soon went into an extended period of inactivity, with few sunspots for many decades thereafter.
Interestingly, Jules Verne, in his novel From the Earth to the Moon, mentions as a reason for going to the Moon that David Fabricius had seen beings living on the Moon. There is no record of his actually making this claim, though, apart from Verne’s book. So, Fabricius may have simply been a well known astronomical name that Verne was using with artistic license for his novel’s plot. However, Jules Verne typically did very good research for his work, so he may have come across some sort of reference to Fabricius in reference to lunar inhabitants. At that time, it had been suggested that the lunar craters were ponds dug by beings living on the Moon.
We don’t know much more about David Fabricius. We know that his son died in 1616 at the age of 29, but I have not heard how he died. Fabricius, himself, died only a year later after being clubbed in the head with a shovel by a person that he had accused of stealing geese. 
Fabricius, though, will always be remembered as the one who discovered the star that we now call Mira (Omicron Ceti) to be a variable star.
I have included here an image of a monument to Fabricius at a church where he pastored from 1603-1617. The image is from Bergali’s blog. Note that the birth date is March 19, 1564. But, I said that today, March 9, is his birthday. How does that work? Did I make a mistake, or is the monument wrong? Well, the answer is neither. This marker gives dates from before the adoption of the Gregorian Calendar. When the new calendar was adopted, the dates were shifted by ten days. So, March 19 under the old Julian Calendar became March 9 under the Gregorian Calendar. I thought that this was an interesting point, but that might be simply because I like calendars.
-Astroprof
