Bava Basra 84a ~ What Color is the Sun?

We are studying the tractate Bava Basrsa (The Last Gate), which is currently dealing with the circumstances under which the sale of goods may be voided.  The Mishnah (83b) ruled that if there is agreement to sell red wheat (שחמתית) and it was found to be white (לבנה), both the seller and the buyer have legal grounds to retract. The Talmud then discusses the names for these colors: what we call red and white are called "like the sun" and "like the moon." Rav Pappa (the Babylonian sage who died in 375CE) took this a step further:

בבא בתרא פד, א

שחמתית ונמצאת לבנה כו': אמר רב פפא מדקתני לבנה ש"מ האי שמשא סומקתי היא תדע  דקא סמקא צפרא ופניא והאי דלא קא חזינן כוליה יומא נהורין הוא דלא ברי

Rav Pappa said: From the fact that the Mishnah refers to one type of wheat as white, we should conclude from this that the sun is red, not white. We know that this is the case, because the sun is red in the morning and in the evening. The reason that we do not see the red color all day is because our eyesight is not strong and we cannot discern the redness of the sun.

Shmuel ben Meir, known as Rashbam (d. ~1158) explained that "our eyes are not able to discern the colors very well because in the middle of the day the light is blinding. But in the morning and the evening, when the sun is less bright, we can see the redness of the sun."

 מאור עינינו אינו ברור כל כך מתוך אור היום שמכהה עינינו אבל צפרא ופניא שהיום חשוך ניכר אדמומית החמה ורב פפא לפרש משנתנו בא אמאי מקרי שחמתית

According to Rav Pappa, the true color of the sun is red - but this true color can be seen only when the sun is at its least intense - in the evening and the morning. We have all experienced Rav Pappa's description: who cannot be moved by the sight of a blazing red sunrise or sunset? But what is the scientific explanation of these colors?

The Color of the Sun in Space, and on Earth

According to NASA experts (who really are rocket scientists, among other things), the sun emits all colors of the visible light spectrum. And when you mix all these colors together you get...white. If you were to look at the sun from high in space, (perhaps aboard the International Space Station), it would indeed appear to be a pure white.  Like this:

Courtesy of NASA.

It was in the seventeenth century that Isaac Newton used a prism to split the sun's light into its constituent colors. Before then it was raindrops that did the same thing, forming a rainbow as a result.

Isaac Newton divided  a ray of sunlight with a prism in a series of experiements published in 1672.  Lego recreation is from here.

The white light of the sun changes as it passes through our atmosphere, which absorbs and scatters much of the shorter wavelength blue light. (That is why the sky is blue, whatever else your dad may have told you.) However the longer wavelength red light is not absorbed, and passes pretty much unchanged.  So we see the sun as more red than blue.  This effect is especially apparent at sunrise and sunset, when in order to reach our eyes, the sunlight has to pass through more of our atmosphere. More of the shorter wavelength blue light is then absorbed, leaving even more of that longer wavelength red light. And as a result, we see those glorious red sunsets (and for those who can get up early enough, red sunrises too).

“Here on Earth, the atmosphere plays a role in the color of the sun. Since shorter wavelength blue light is scattered more efficiently than longer wavelength red light, we lose some of the blue tint of the sun as sunlight passes through the atmosphere. In addition, all wavelengths of visible light passing through our atmosphere are attenuated so that the light that reaches our eyes does not immediately saturate the cone receptors. This allows the brain to perceive color from the image with a little less blue – yellow. ”

— NASA

The Cultural determinants of the Sun's Color

On their website, the NASA scientists claim that "sometimes the display color of the Sun is culturally determined. If a kindergartener in the USA colors a picture of the Sun, they will usually make it yellow. However, a kindergartener in Japan would normally color it red!"  The rabbis of the Talmud had their own cultural explanation of the colors of the sun.  After later suggesting that the color of the sun may actually be white (because that is the color of a patch of skin with zora'at, usually identified as a kind of leprosy), the Talmud then explains the cause of the red sunrises and sunsets:  

ולמאי דסליק דעתין מעיקרא הא קא סמקא צפרא ופניא בצפרא דחלפא אבי וורדי דגן עדן בפניא דחלפא אפתחא דגיהנם

In the morning it becomes red as it passes over the site of the roses of the Garden of Eden, whose reflections give the light a red hue. In the evening the sun turns red because it passes over the entrance of Gehenna, whose fires redden the light...

Without the scientific understanding we have today, the Talmud claimed that the red color of sunrise and sunset was due to the light filtering though the red roses of the Garden of Eden, and fires of Hell.

is the Garden of Eden real or metaphorical?

It would seem that the Talmud's description of the locations of the Garden of Eden and the Gates of Hell is to be taken literally, for it is given as an explanation for physical phenomena.  But here is where things can get tricky. The famous rabbi Joseph Hayyim of Baghdad (1834–1909) wrote a work that is widely read by Sephardic Jews to this day called Ben Ish Hai. He also  published three volumes of responsa between 1901 and 1905 called Rav Pe’alim. (A fourth volume was posthumously published in 1912.) In an undated question, R. Hayyim was asked about the location of the Garden of Eden. In one tradition, the garden was located “on the other side of the world,” somewhere below the equator in the southern hemisphere. However, the questioner continued, the world has been circumnavigated, and the Garden of Eden has not been identified. Where then is it located?

In his answer, R. Hayyim digressed into the truth claims of science, and then returned to the location of the Garden of Eden. He noted that although it may be located on the Earth itself, it existed on a different spiritual plane and would therefore not be perceived by the human senses. I suppose many moderns would agree with the suggestion that the Garden of Eden is not to be found in a geographic location. But today's page of Talmud reminds us that at least in talmudic Babylon, the Garden of Eden was not just a metaphor.  It determined the very colors of the sun.

Bava Basra 74a ~ Where Heaven and Earth Touch

While discussing the legal technicalities involved in buying a boat, the Talmud digresses with a series of fantastic stories about boats, told by Rabbah bar bar Chanah.  And then it digresses again with a series of  fantastic stories about all kinds of things, also told by Rabbah bar bar Channah. In total he told fifteen stories. Here is the last one:

בבא בתרא עד, א

אמר לי תא אחוי לך היכא דנשקי ארעא ורקיעא אהדדי שקלתא לסילתאי אתנחתא בכוותא דרקיעא אדמצלינא בעיתיה ולא אשכחיתה אמינא ליה איכא גנבי הכא אמר לי האי גלגלא דרקיעא הוא דהדר נטר עד למחר הכא ומשכחת לה

An Arab also said to me: Come, I will show you the place where the earth and the heavens touch each other. I took my basket and placed it in a window of the heavens. After I finished praying, I searched for it but did not find it. I said to him: Are there thieves here? He said to me: This is the heavenly sphere that is turning around; wait here until tomorrow and you will find it again.

What should we make of this?  We should begin by considering its context, noting that it is part of a series of fantastic fables.  These include a man who pursued a demon on horseback, antelope the size of mountains, giant frogs ("the size of sixty houses") that are eaten by even more giant birds, a fish so large it took three days to sail between its fins, and scorpions the size of donkeys. You get the idea. Given this context, perhaps the tale of a place where heaven and earth touch as a description of reality should be taken with as much seriousness as the other stories. Which is to say, not very seriously at all. 

Other Talmudic descriptions of the Cosmos

Not so fast. There are other rabbis in Talmud who address the structure of the earth and the cosmos. Rabbi Natan noted that the stars do not seem to change in their positions overhead when walking far distances.  The assumption underlying his explanation for this observation was that the earth is flat. Covering the earth was an opaque cap referred to as the rakia, which is most commonly translated as the sky or firmament. Rava, a fourth-century Babylonian sage who lived on the banks of the river Tigris, determined this cap to be 1,000 parsa in width, while Rabbi Yehudah thought that he had over-estimated this thickness. There were others who added to the picture of the sky; Resh Lakish announced that it actually was made up of seven distinct layers. Given this model, there would have to be a place where the opaque cap touched the earth, a place that Rabbah bar Bar Channah claimed to have touched.  So even allowing for a degree of talmudic fantasy, this fable was clearly built on the model that was shared by other rabbis in the Talmud.

The Flammarion Engraving

In 1872, Camille Flammarion published L'atmosphère: météorologie populaire (The Atmosphere: Popular Meteorology). In the 1888 edition this engraving  appeared on page 163:

As you can see from the caption, the engraving is "A missionary of the Middle Ages tells that he had found the point where the sky and the Earth touch." The engraving appears to have been specially created for Flammarion's book. The text that precedes it reads as follows:

Whether the sky be clear or cloudy, it always seems to us to have the shape of an elliptic arch; far from having the form of a circular arch, it always seems flattened and depressed above our heads, and gradually to become farther removed toward the horizon. Our ancestors imagined that this blue vault was really what the eye would lead them to believe it to be; but, as Voltaire remarks, this is about as reasonable as if a silk-worm took his web for the limits of the universe. The Greek astronomers represented it as formed of a solid crystal substance; and so recently as Copernicus, a large number of astronomers thought it was as solid as plate-glass. The Latin poets placed the divinities of Olympus and the stately mythological court upon this vault, above the planets and the fixed stars. Previous to the knowledge that the earth was moving in space, and that space is everywhere, theologians had installed the Trinity in the empyrean, the glorified body of Jesus, that of the Virgin Mary, the angelic hierarchy, the saints, and all the heavenly host.... A naïve missionary of the Middle Ages even tells us that, in one of his voyages in search of the terrestrial paradise, he reached the horizon where the earth and the heavens met, and that he discovered a certain point where they were not joined together, and where, by stooping his shoulders, he passed under the roof of the heavens.

Flammarion does not reference his source for the missionary of the Middle Ages who, like Rabbah bar bar Channah, claimed to have found the place were the heavens and earth meet.  Despite this, his engraving has become very popular. A version of it appears on the cover of Daniel J. Boorstin's best selling work The Discoverers, and inside William Vollmann's Uncentering the Universe. And those are just the ones I know about from my own library. You can buy a color poster of it (where it is incorrectly described as a "medieval artwork") but if you are really dedicated you could always travel to San Fransisco where a tattoo parlor will create the image on your arm. 

We know that Rabbah bar bar Channah's model of the universe is not correct, but his suggestion of a place where heaven and earth touch is both endearing and enchanting.  (It is also the perfect name for an anthology of Midrash which was published back in 1983).  With Passover approaching, you may already be thinking about your wine list for the Seder.  Perhaps you should consider a kosher-for-Pesach wine whose label shows part of the Flammarion etching, and drink to the memory of Rabbah bar bar Channah. 

Bava Basra 27b ~ The Roots of a Palm Tree

בבא בתרא כז ,ב

אמר עולא אילן הסמוך למצר בתוך שש עשרה אמה גזלן הוא ואין מביאין ממנו בכורים עשרה אמה... ותו לא והא תנן מרחיקין את האילן מן הבור כ"ה אמה אמר אביי מיזל טובא אזלי אכחושי לא מכחשי אלא עד שש עשרה אמה טפי לא מכחשי

Ulla said: An individual who owns a tree that is within sixteen cubits of a boundary is a robber, [since it draws nourishment from the neighbor’s land,] and one does not bring first fruits from it, [since that would be a mitzva that is fulfilled by means of a transgression]... But do roots extend sixteen cubits and no more? Didn’t we learn in a Mishnah (25b): One must distance a tree twenty-five cubits from a cistern? [This indicates that tree roots reach more than sixteen cubits.] Abaye said: The roots extend farther, but they drain the earth of nutrients within sixteen cubits; with regard to an area any more distant than that, they do not drain the earth.

The Root Systems of the Date Palm Tree

While the Talmud doesn't specify the kind of tree that must be distanced from others, in Mesepotamia the most likely candidate was the Date Palm, Phoenix dactylifera. These trees grow to a height of 75 feet, and you've seen plenty of them if you've driven south towards Eilat.  Here is their root system:

USDA image from Chao. C, Krueger R. The Date Palm (Phoenix dactylifera L.): Overview of Biology, Uses, and Cultivation. Hort. Science 2007 42(5); 1077-1082.

To whom shall we turn to get information about the size of that root system? The United Nations Food and Agriculture Organization, of course.  According to a helpful document by a member of their Date Production Support Programme, "Roots are found as far as 25m from the palm and deeper than 6m, but 85 percent of the roots are distributed in the zone of 2 m deep and 2m on both lateral sides in a deep loamy soil." But the 25m (82 foot) roots are an extreme. Most of the roots extend about 10m (about 32 feet).

Table from here.

It would appear that Abaye was referring to the average reach of the zone II roots. Assuming that a talmudic amah is between 48-57cm, Abaye's figure would put the zone II distance of at 7.6-9.1 m. That's right in keeping with the 10m average figure from the UN document.  Good to know that on these important matters, the UN and the Jewish People are in agreement.

Image from here.

Bava Basra 25b ~ The Sun's Orbit Around the Earth

בבא בתרא כה, א–ב

תניא ר"א אומר עולם לאכסדרה הוא דומה ורוח צפונית אינה מסובבת וכיון שהגיעה חמה אצל קרן מערבית צפונית נכפפת ועולה למעלה מן הרקיע ורבי יהושע אומר עולם לקובה הוא דומה ורוח צפונית מסובבת וכיון שחמה מגעת לקרן מערבית צפונית מקפת וחוזרת אחורי כיפה 

Rabbi Eliezer taught: The world is similar to a partially enclosed veranda [אכסדרה], [which is enclosed on three sides] and the northern side of the world is not enclosed with a partition like the other directions. When the reaches the northwestern corner it turns around and ascends throughout the night above the rakia [to the east side and does not pass the north side].

Rabbi Yehoshua says: The world is similar to a small tent [קובה], [and the north side is enclosed too,] and when the sun reaches the northwestern corner it orbits and passes behind the dome.

The monthly movement of the Earth, Moon, and Sun, according to Moses Hefez, Melekhet Mahashevet, Venice, 1710. From here. 

In this passage the path of the Sun is described, and to understand it you need to know this. The rabbis of the Talmud believed that the earth was a flat disc, and that above the sky was an opaque covering called the rakia. During the day the Sun was visible under the rakia, and then at night it zipped back from where it set in the west to where it would rise again in the east by traveling over the rakia. Something like this: 

From Judah Landa. Torah and Science. Ktav 1991. p66.

The other place that you will find the path of the Sun discussed in the Talmud is in Pesachim 94b.  Here is the text:

חכמי ישראל אומרים ביום חמה מהלכת למטה מן הרקיע ובלילה למעלה מן הרקיע וחכמי אומות העולם אומרים ביום חמה מהלכת למטה מן הרקיע ובלילה למטה מן הקרקע א"ר ונראין דבריהן מדברינו שביום מעינות צוננין ובלילה רותחין

The wise men of Israel say that during the day the Sun travels under the rakia, and at night it travels above the rakia. And Gentile wise men say: during the day the Sun travels under the rakia and at night under the Earth. Rabbi [Yehudah Hanasi] said: their view is more logical than ours for during the day springs are cold and at night they are warm.

From this is discussion it is once again apparent that in the talmudic view, the sky must be completely opaque. As the Sun passes over the top of the sky at night, it is not in the slightest way visible.

Also from Landa, p63

It is hardly news to point out that a long time ago people believed that the universe was different to the way that we understand it to be today. But the belief of the rabbis of the Talmud was standard until only very recently, by which I mean only a few hundred years. 

Copernicus and his critics

When Nicolas Copernicus (d. 1543)  proposed his heliocentric universe he did so for a number of mathematical reasons but without any evidence. The experimental evidence that supported his claim did not appear for over three hundred years, when in 1838 the first measurement of stellar parallax occurred. Without evidence to support the Copernican model, many rejected it.  For example, the famous Danish astronomer Tycho Brahe (1546–1601) rejected the Copernican model, and came up with one of his own in which all the planets orbited the sun, which in turn dragged them around a stationary earth. For about one hundred years after Copernicus, the universities of Oxford and Cambridge ignored the heliocentric model entirely, and the English philosopher, statesman, and member of Parliament Francis Bacon (1561–1626) rejected the Copernican model as having “too many and great inconveniences.”

Galileo and the Catholic Church

Galileo published his discovery of the four satellites of Jupiter in Sidereus Nuncius in 1610. This discovery did not prove that Copernicus was correct, but it lent a great deal of corroborative evidence to the Copernican model. In addition Galileo noted that Venus seemed to change shape, just as the Moon did, sometimes appearing almost (but never quite) full, sometimes as a semi-circle, and at other times as sickle-shaped. The best explanation was that Venus was not orbiting the earth, but that it was in fact orbiting the Sun. And that turned out to be correct too. But as we know, things didn't tun out to well for Galileo. The Catholic Church, which by now had placed Copernicus' book on its Index of Banned Books, also banned Galileo's Dialogue Concerning the Two Chief World Systems - the book in which he outlined his proofs that the earth orbited the sun. The works of the astronomer Johannes Kepler (d.1630) were also added to the Index.  

The Jesuit Edition of Newton's Principa

In 1687 the Copernican model found support with the publication of Newton’s Principa Mathematica. In that work, Newton described the universal laws of gravitation and motion that were behind the observations of Copernicus, Galileo, and Kepler.  The book went through three Latin editions in Newton’s life-time, and an English edition was published two years after his death in 1727.  A new three-volume edition of the Principia was published in Geneva between 1739 and 1742.  This edition contained a commentary on each of the book’s propositions by two Franciscan friars but was noteworthy for another reason. In its final volume, the “Jesuit edition”  contained a disclaimer by the friars distancing themselves from the heliocentric assumptions contained in the book:

Newton in this third book assumes the hypothesis of the motion of the Earth. The propositions of the author cannot be explained otherwise than by making the same hypothesis. Hence we have been obliged to put on a character not our own. But we profess obedience to the decrees promulgated by sovereign pontiffs against the motion of the Earth.

So it wasn't just the rabbis of the Talmud who believed the earth stood still.  In fact they believed what (nearly) every one else continued to believe for at least a thousand years. The sun certainly looks like it revolved around the earth, so they created a model of the universe in which it did so, either by circling under the earth at night, or by zig-zagging back across the top of the rakia. Neither model turned out to be correct.  But in believing this, the rabbis were firmly in the majority.

[If you want more on this subject, Natan Slifkin has an excellent monograph on the Path of the Sun at Night. I'm also told there's an excellent book on the Jewish reception of Copernican thought.]