The Red Sirius
Posted 26 October 2009 - 08:39 PM
Cicero, in his translation of Phaenomena 326-34, writes, rutilo cum lumine claret fervidus ille Canis, ¡°with ruddy light fervidly glows that dog.¡±
I don't know how I missed this before. Here "rutilus" (translated above as "ruddy") does not refer to the the color of Sirius alone; it refers to the light of the constellation Canis, i.e., multiple stars. This is particularly clear if you add the rest of the sentence from Cicero: "stellarum luce refulgens", "flashing with the light of stars" (plural). There seems something similar could be going on in Aratus' original, where "poikilos" could make sense with its normal definition if it refers to the constellation.
Anyway, my initial excitement at seeing this article join two of my favorite interests has long subsided. I've only continued this long out of irritation. I think the author does not read Latin or Greek except in translation.
Posted 27 October 2009 - 09:15 AM
It is the responsibility of anyone who lends credence to the idea that somehow, in violation of physics as we know it, Sirius was red in color only a couple thousand years ago to explain HOW Sirius could have been red.
Your argument that the words of scientifically illiterate people should hold any water is as implausible as the arguments that the alignment of the planets can foretell one's personality.
1. One of the defining features of science is its answering to empirical observations. While some observations require sophisticated instruments, there are also observations--and in particular the observations of the visual color of bright stars--that do not require sophisticated instruments. To throw out observation reports because they do not fit the theory is not good scientific procedure. It is not necessary for the observer to have a theory to explain his or her observations. And if we required observations to be compatible with existing theory, we would stop much scientific progress.
2. Our knowledge of stellar evolution rests on observations of stars at different stages, combined with a good dollop of theory. On the theory side, it is certainly not the case that the stellar evolution predictions are derived from the most basic laws of physics (not that we know what these are, either). Rather, various approximations are made, computer simulations of simplified models are done, and so on. I suspect--I do not know in this case--that significant parts of the models are derived not from fundamental laws, but are "phenomenological", simply a best fit to the observational data.
3. One of the limitations of the observational data we have is that while we are fortunate enough to observe objects of different ages, we are rarely able to observe the very same object at significantly different ages in its own evolution. Potentially, ancient astronomical observations are a way of supplying for that defect in our data. Such observations potentially provide data that we did not have available when we created the current theories of stellar evolution, and it is not scientifically responsible to discount it.
4. As for the scientific illiteracy of the observers, they were smart people. Greek mathematics was sophisticated. Just pick up Euclid, and see how quickly you can fill in all the proofs yourself. :-) Sure, many of them had astrological beliefs. But while it would be irrational for you or me to believe that the positions of the planets at birth affect us in significant and predictable ways, it is far from clear that it was irrational at the time to believe it. What is and is not rational to believe is dependent on the evidence or data available. Given the evidence Newton had, believing in General Relativity would probably have been irrational. Given the evidence we have, believing classical physics to be true (not merely as an approximation) is irrational. This is not a relativism, of course--I am not saying that Newton and Ptolemy are just as right as we are. We do, after all, have more data than they did. But while our scientific theories are closer to the truth than those of Newton and Ptolemy, we would be unjustified in saying that our present scientists are more rational than Newton and Ptolemy were.
5. All that said, I do wonder--as a previous commenter said--about the extent to which the perception of color can be affected by how one thinks of the stars. If one thinks of the stars as flaming, then one might see them as redder than they are. Probably not to the extent of seeing Sirius as red, though, except low on the horizon. And it is also true that some, though not all (presumably not Ptolemy), of the ancients were more likely to look at what their predecessors wrote than at what is up in the sky.
Posted 27 October 2009 - 09:18 AM
and here is a summary of the matter from 1984
Google Books link
I will try to find more.
Posted 27 October 2009 - 11:16 AM
The main point here is that there is doubt about the historical record concerning the color of Sirius. If every single record or account that mentioned star color had Sirius clearly stated as being a red color, then it might be worthy to give the reports a little more weight. However, as reported, this was not the case. Some of the reports merely indicated a possible reddish hue, while others in the same period (the Chinese for example) did not. The current astronomical and astrophysical facts behind red color for stars do not support the idea of Sirius being reddish any time within the historical record time period. This, plus the less than conclusive descriptive record, must point to the likelyhood that Sirius has not been red anytime in the past few thousand years or so. I think that is where the facts leave us. Clear skies to you.
Pretty much sums it up. The evidence isn't conclusive either way, but as things stand, the most economical explanation is that the current theories of stars are right and the ancient observers who said that Sirius was red were wrong -- or misinterpreted.
Although the Greeks were dazzling thinkers, respect for empirical data -- especially data that ran counter to their theories -- was *not* one of their strong points.
Posted 27 October 2009 - 01:58 PM
Posted 27 October 2009 - 03:29 PM
The 'red Sirius' really is an interesting question, but more a cultural and philological one than astrophysical. By trying to prove that Sirius was 'red' in Western antiquity, I think we're losing an opportunity to learn a great deal about ancient observations, terms used technically (not to mention poetically), and analytical techniques. The fact that we have to force meanings on words and ignore and contort quotes to prove what is almost ceratinly an astrophysical impossibility speaks volumes.
Posted 27 October 2009 - 05:52 PM
The evidence isn't conclusive either way, but as things stand, the most economical explanation is that the current theories of stars are right and the ancient observers who said that Sirius was red were wrong -- or misinterpreted.
Although the Greeks were dazzling thinkers, respect for empirical data -- especially data that ran counter to their theories -- was *not* one of their strong points.
Your summary of things--especially the phrase "economical explanation"--is, I think, right on the mark. Precedence must be given to modern astronomical theories of stellar evolution while keeping in mind that here we have a body of ancient data that has, since it was noticed by Thomas Barker in 1760, been difficult to explain--or explain away.
Most of the statements about a red Sirius are from Romans or Greeks who worked during the height of Roman civilization (1st cent. BC to 2nd cent AD). Though the Greeks of the Hellenic age indeed seem to have been more inclined to the desk than to the field, the Romans were not. Concerning the Roman Epicurean philosopher Lucretius (a contemporary of Cicero), the American Classicist Tenney Frank wrote,
"Lucretius also responded to Roman tempermental inclinations when he stressed the importance of observation and inductive logic in philosophy. The Romans of the Republic disliked mysticism and were ripe for a cosmology that substituted sense perception for vague mystery. They were also impatient of abstractions, and made little progress with such deductive sciences as mathematics. . . . Democritus [whom you will remember was the 'inventor' of the atom] had long ago proposed the hypothesis of natural creation, and Lucretius accepted the theory from Epicurus. What Lucretius himself saw was the need of emphasizing to the Romans the method the approach by induction from observable data . . . Beneath every statement [in an argument in Lucretius' first book] there lies a mass of careful observation, tested by what John Stuart Mill calls the method of "agreement and difference," and these valid conclusions are in turn used for the final induction . . ." ("Life and Literature in the Roman Republic" Chapter VIII)
Educated Romans tended to ally themselves with either the Stoics or the Epicureans; thus the ideas of Lucretius had a wide hearing. Thus observation in the modern scientific sense WAS part of Roman culture.
But these are just words. Where is the evidence that the Romans actually practised observation and inductive reasoning on any scale? That evidence is in fact all over southern Europe and the Mediterranean. It is Roman architecture. For what are architecture and engineering but applied physics? The Roman buildings that still stand in whole or large part prove that the Romans had mastered that branch of physics called statics. They understood the effects of gravity. They understood thrust and the principle that "every reaction has an equal and opposite reaction." They knew how to channel thrust through the weight-bearing walls and pillars of a structure. Think of the Pantheon in Rome, a domed structure that has stood whole for nearly two millennia in an earthquake zone! The number of Roman archs that survive around the Mediterranean are literally uncountable. By contrast, the Interstate 35W bridge just upriver from my alma mater stood just 40 years--and it didn't have to face earthquakes and wars.
Some of Roman knowledge about architecture has survived in Vitruvius' "On Architecture," a work not superceded until the Renaissance. But the Romans were not people of the desk: they'd rather be doing than writing. I've known a lot of tech-men who are that way. But when they did write, most of them were careful about what they said. In the early books of his "History," Livy again and again warns readers that what he is narrating is only legend, but the only information about the early centuries of Rome that survived. However, excavations on the Capitoline and Palatine and under the Forum have confirmed the substance of Livy's account. A Danish excavation in the 1980s reconfirmed the Livian date of about 490 BC for the founding of the Temple of Castor. . . .
. . . but Roman archaeology is one of my favorite subjects, so I'd better stop before I run on worse than I have. The point is that educated Romans were alert and careful observers of the world around them and knew how to apply observational knowledge in numerous fields of human endeavor--including astronomy.
Posted 27 October 2009 - 06:35 PM
Today, there are not many stars near the same declination of Sirius. The obvious, Rigel is white, just like Sirius. Is Rigel also described as being red? No? Then Sirius had to be red while Rigel was not, suggesting an astrophysical reason.
I find it hard to believe that every seasoned astronomer of that era viewed the sky through flames and smoke. They would have known (as we do now) that the sky is much better viewed from outside fire's influence.
Does anyone mention Fomalaut, Canopus, Spica or Antares? If all of them are described as "red" or "ruddish" then there is certainly an atmospheric connection somewhere. With the exception of Antares, all are clearly white or nearly so.
Procyon is a good example of a star that has some issues with respect to the observer. Many would see it as white, but seasoned observers know that it has a slight orange or red quality.
I can't see Sirius b as an explanation. No one in history commented on how Sirius became progressively whiter over time. You would think that someone would have noticed, Sirius being such a bright star and all! If Sirius is indeed getting whiter, spectroscopic analysis would have revealed that; even today. In the past 100 years, no one has commented on Sirius' spectral lines changing.
We can see Sirius as red or orange today, especially those who live on the eastern seaboard of the U.S. On a very humid night in September, go see Sirius just before dawn. I am sure that you would see red too. If humidity levels were high at the venues, Sirius could be red. However, if the humidity levels became low again, Sirius would once again appear white.
On the outside, the only event I can possibly think of is absorbing dust in between Sirius and the Earth. However, if the dust is heavy enough to turn Sirius red, it would have also greatly diminished its apparent brightness, thus removing it from the altar of ancient worship.
However, there is another angle. It is possible that the area of observation was polluted with volcanic activity. The Mediterranean has both Mount Etna and Mount Vesuvius. This might explain how the Greeks called Sirius red and the Chinese did not. Volcanoes would also diminish the apparent brightness of the stars and would have turned them all red.
Unless we can go back in time and ask them and see Sirius for ourselves, it will be a mystery for many years to come.
Posted 28 October 2009 - 10:56 AM
In the the Hellenic world, there was no distinct beast called "science". Fields we today classify as "metaphysics", "astrology/mysticism", "astronomy and physics," "mathematics", etc., were not distinct in ancient times. Ergo, the purpose of an ancient observer in conducting observations is unlikely to have been the same as our purpose for conduction similar observations today.
Now for some speculation. While observing bright stars like Sirius at the moment of their rising and setting at different times of the year is not the most common context of observation today, in the Ancient near east and Mediterranean it was likely the predominant context for such observations. Descriptions of "flaming" or "fiery" Sirius seem particularly apt for a Sirius just risen, viewed through miles of turbulent atmosphere. Perhaps earlier observations describing low elevation observations of Sirius as "like fire" were perpetuated by later writers.
In any case, I think that it is crucially important to recognize that what the ancients thought they saw when they looked at the night sky is not what you and I think we see. To understand the "what" of what they saw, I think you have to mindful of the "why" as in why were they observing in the first place. In my view, the later learned records by non-observers like Cicero were likely based on the records of earlier observers like Ptolemy. Ptolemy, on the other hand, was as much a meta-physicist and mystic as astro-physicist. I wouldn't be surprised to learn that his observations of Sirius were conducted near the horizion, often at or near sunrise or sunset, and that his purpose was not simply self-indulgent "scientific curiosity" in making the observations.
Posted 28 October 2009 - 02:56 PM
We have a quote from Hephaestion of Thebes (Ceragioli, note 72 has the Greek text) describing how if the star's color upon rising was inspected as an omen. Curiously, he menitions that the star is "white" ("leukos"). This agrees with Hyginus' description of Sirius as being remarkable for its "candor", which is usually from the context interpretted as "brightness", but almost certainly implies a white tint. Add to these, Manilius and Avienus, who explicitly describe the star Sirius as "blue" or perhaps "blue-white".
Given this type of interpretation, we can perhaps understand the truly unambiguous references to Sirius' color as red (not its fierieness or the color of Canis the constellation), which actually only seem to occur a few times: In Seneca, where we're told the celestial bodies have not inherent color, but acquire it through atmospheric effects (passage cited by Crossen, although not in full context), and in Horace where he refers to Sirius as "rubra"(not cited in Crossen) in the context of extreme heat.
Since we can see that there was an awareness and assumed meaning in the color seen in Sirius, perhaps Ptolemy's characterization of the star as "hypokirros" is a guess at the star's "actual" color, since we don't know if he shared an assumption with Seneca that celestial bodies have no inherent color. There is very little context to make a guess, although several astronomers (most notably See, whom Crossen seems to follow) took up the task and piled up dubious citations leading ultimately to the conclusion that the ancients saw Sirius as a "fiery red" star all the time.
Posted 28 October 2009 - 10:31 PM
Posted 29 October 2009 - 12:06 AM
One thing that does intrigue me, though, is the possibility of seeing Sirius just as it appears over the horizon. I'm not referring to it simply being ten or twenty degrees above the horizon, but just a few degrees above it. In this day and age that would be unlikely in most of the world, but in the period of time that is being discussed here, it would seem like it might be possible due to the lack of pollutants in the air.
If you were out in the middle of an empty plain - or on the Mediterranean with a clear view of the eastern horizon - back in that era, and if you could actually catch Sirius a couple of degrees above the horizon - especially on a warm August morning - chances are pretty darn good it would be red.
Posted 29 October 2009 - 06:20 AM
I lived and worked on our family farm until I was 39 years old (with a 5-year exile in Minneapolis to attend the U of MN), and during the last ten years of that period was an active observer--as well as frequently outside during evenings doing normal farm work. Our farm was two miles from the nearest village out under extremely dark skies. During that decade I had the opportunity to observe Sirius rising or setting dozens of times under a wide variety of atmosphere conditions. When the atmosphere was thick with dust or humidity the star was too dimmed to have much color: when it got a few degrees above the horizon one might have described it as a sort of "dull ruddy", which quickly faded into a pale yellow and then off-white. But under average conditions the star appeared as a scintillating gem best described by Aratos' "many-colored" (poikilos). Red, yellow, and blue-white predominated, alternating almost too quickly to be sure you really saw them. It was like looking at the star through a fractured piece of glass and impossible under those circumstances to judge the star's "rest color". It's always been clear to me that Aratos was describing the rising or setting Sirius, not the Sirius ten or twenty degrees above the horizon.
Posted 29 October 2009 - 02:02 PM
That observation of yours convinces me that you must be sincere in your aims, although (sorry) a little weak in Greek and Latin. Please consider re-examining this topic before publishing your book -- there is much still in the topic that should interest observers without posing the stumblingblock of an actual change in Sirius' color. At least read Ceragioli and consult Greek and Latin scholars for review.
Posted 31 October 2009 - 07:42 PM
Posted 10 March 2010 - 08:34 PM
It looked whitish blue to me.
Posted 05 April 2012 - 12:21 PM
If you enjoyed my Journal for the History of Astronomy articles from 1995, you might even more enjoy my Ph.D. dissertation in Ancient Greek and Latin for Harvard University: "Feruidus Ille Canis: The Lore and Poetry of the Dog Star in Antiquity" (1992). It's fun to endlessly speculate on this topic, and feel free to continue! For myself, after rather exhausively surveying the ancient Greek and Latin evidence, texts and coinage (!), my conclusion in the dissertation (reflecting a fuller investigation than that of the articles) was that the complex of texts suggesting a reddish coloration in Sirius while reflecting the meteorological fact that at heliacal rising Sirius can appear reddish, mainly reflects a basis in folklore and mythology. That is, cultural anthropology. There's no reason to think that Sirius (A or B) has literally undergone a drastic astrophysical change in a mere 2000 years, as far as I can tell.
Different cultures (us too) always find it nearly impossible to understand one another except through the agency of stories comprehensible in their own (limited) intellectual framework.
Cheers and all the best,
Roger C. Ceragioli
Posted 05 April 2012 - 03:13 PM
I think you're probably correct. Sirius is bright and with a healthy dose of atmospheric refraction thrown in near the horizon, flashes fiery red and can manifest a ruddy limb.
Another thing folks sometimes point at to suggest color perceptions were different in antiquity are Homeric references to "wine-dark sea". I think the problem isn't with changes in optical physiology or perception, but rather the fact that we moderns tend to think of wine in our own material context.
What do we drink wine from? Clear stemware. The color of the liquid is unmistakable in such a vessel. During the Mycenaean period, drinking vessels were opaque stoneware or pottery. Red wine would have been inky-dark in a stoneware mug, just as the Mediterranean is inky dark when seen from the rail of a ship.
Wine-dark is literally correct in that material culture context, and I don't think implied "redness".
Posted 21 April 2012 - 04:52 AM
I can add one thing to the article that did occur to me during the past two years. The argument that the ancient authorities were referring to Sirius only as it rises and sets cannot solve the mystery because the ancients clearly would have observed the star when it was higher in the sky, and if it was bluish-white when higher, that fact certainly would have been remarked upon by an authority like Ptolemy. All the stars described by Ptolemy as red are not only reddish while rising, but also reddish while culminating (except for Pollux, which is yellow). Given the fact that in the best ancient philosophies the heavens were considered the realm of the Immutable and the Changeless (meteors and comets were regarded as sub-lunar phenomena), the fact that the brightest fixed star changes from red to white would certainly have created some concern and come in for some comment!