How many stars did Rashi think there were?

Question

According to the Chabad translation, Rashi on Deut. 1:10 implies that there are more than 600,000 stars:

The Lord, your God, has multiplied you, and behold, you are today as the stars of the heavens in abundance. (Deut 1:10)

And, behold, you are today as the stars of the heavens: But were they [the Israelites] on that day as [many as] the stars of the heavens? Were they not only six hundred thousand?

(Rashi's question is resolved by saying that they are as eternal as the stars, but it still raises the question.)

Of course today we know this to be true (in fact, current estimates are on the order of hundreds of sextillions of stars in the observable universe), but Rashi said this before the advent of the telescope, during a time when there were perhaps a couple thousand stars cataloged.

Are there any indications elsewhere of how many stars Rashi thought there were, or perhaps if other Torah sources said something similar to Rashi? (Is it even a proper understanding of the Rashi? I'm going off an English translation.) Perhaps there were philosophers or astronomers at the time who said there must be many more stars than could be individually counted, I don't know.

Answer 1

Around 1.06434e+18.

The Gemara in Brachos says

י"ב מזלות בראתי ברקיע ועל כל מזל ומזל בראתי לו שלשים חיל ועל כל חיל וחיל בראתי לו שלשים לגיון ועל כל לגיון ולגיון בראתי לו שלשים רהטון ועל כל רהטון ורהטון בראתי לו שלשים קרטון ועל כל קרטון וקרטון בראתי לו שלשים גסטרא ועל כל גסטרא וגסטרא תליתי בו שלש מאות וששים וחמשה אלפי רבוא כוכבים

Hashem created 12 constellations.

To each constellation He assigned 30 Chail.

For each Chail, He created 30 legions.

For each legion, He created 30 rehatons.

For each rehatons, He created 30 kartons.

For each karton, He created 30 Gistera.

For each gistera, He created 365*1000*10000 stars.

The result comes up to 12*30*30*30*30*30*365*1000*10000

Answer 2

I might venture a couple sheer guesses of what it might possibly mean. If anyone might know of any merit to the guesses, please let me know and I can improve this answer.

1. Rashi may have recognized that the milky light of the Milky Way is made up of many stars. Although only a one or two thousand could be individually identified, he figured the glow was from an uncountably high number of other stars.

2. Rashi may simply be indicating that they weren't at their maximum of multiplicity.

Answer 3

The question behind the question is whether statements from religious tradition should be taken seriously by scientists. These are statements made at a time when there were no human beings were aware of concepts such as galaxies. There are about 9,000 stars visible on a clear, moonless night, yet 2,000+ years ago the Talmud quotes a tradition that there are 10^18 stars.

Science is proud of its accuracy, yet when counting stars there is a great deal of guess work. Stars are counted in a small area and then extrapolated to be evenly distributed. Science estimates about 10^11 or 10^12. The key here is defining what is counted as a star. Next, galaxies are counted in a small area and extrapolated to be evenly distributed. Right now, that is also estimated to be about 10^11 to 10^12. The resulting estimate for the total number of stars is therefore 10^22 to 10^24. (Just as an aside, if religious tradition made the claim that the average number of stars in a galaxy is almost exactly the number of galaxies in the universe I think science would have a problem with the coincidence.)

My feeling is that statements from religious tradition are like the answers in the back of a text book. If you work a problem and come up with a different answer then the first response should be to make sure that the problem was understood correctly, not that the answer given was a mistake. It is possible that the question is not the same. Here, perhaps the definition of a star is different or the definition of the size of the universe is different.

For the question of the size of the universe, the size of the "observable universe" changes as science progresses. Does that mean that the number from tradition is only valid for a specific level of scientific ability? Perhaps the number of stars will continue to increase and the traditional value will become progressively more wrong. That would not seem to be the universal result expected from religion. As a possible response, the "future visibility limit" may mean that the largest the number of observable stars can only ever be 2.36 times the current number of observable stars, which locks us in to about the current order of magnitude. The number of grains of sand is often compared to the number of stars in the sky. I find one estimate of 10^18 and another of 10^24 (Sorry, but I am limited to 2 links, so you have to do the search yourself if you are interested). The 10^18 is based on grains of sand on the beach. This is not unreasonable, just a matter of definition. Perhaps the equivalent number for stars is based on a similar restrictive definition. In any case, religious traditional values do not seem to be out of line.

In the US (in 2009) there were 193 million "light duty vehicles, short wheel base," 40 million "light duty vehicles, long wheel base," 10 million trucks, and 9 million motorcycles. Using 10 million as the unit of measure, if asked the number of cars, either 19 (defined as cars) or 25 (defined as vehicles) would both be reasonable answers.

So, 2,000+ years ago nobody ever saw more than 10^4 stars, but the Talmud says that tradition puts the count as about 10^18. With all of our advances in science, without a clear definition of what is being counted, say that the number is more like 10^22 to 20^24.

This is supposed to discredit Rabbinic Torah?

Answer 4

Talmud Berachos 58b "What is the meaning of Kima? (Kima is a group of stars)...Shmuel says: Kima is like a hundred stars." (Kima is the conjunction of the Hebrew K' (like) and Meah (100).)

Most traditional commentaries say that Kima is the Pleiades star cluster. It is known that the naked eye can see about 7 of them (the 7 sisters).

In reality, a quick search of scientific and secular websites on google will show that this star cluster contains anywhere from 100 - 3000 stars. I guess the question is what makes a star truly part of Kima, or just surrounding or close to it?

Interestingly, the Talmud continues with the next line that further describes the cluster: "some say that these stars are gathered together, and some say they are scattered."

So, compare that, to this quote from Wikipedia: "Astronomers estimate that the cluster will survive for about another 250 million years, after which it will disperse due to gravitational interactions with its galactic neighborhood."

Right now they are together, however, they are scattering.

This Talmudic passage seems to describe a literal measure of stars (not visible to the naked eye); and not a Medrashic exaggeration. It was Shmuel's response to a question being posed to him after the Talmud introduced him as knowledgable in astronomy.

Rashi would normally derive his opinion from Talmudic and Medrashic sources.

Rashi also comments on this Gemara itself (Berachos 58b above) : "like 100 stars: There are (these 100 stars) among the cluster of Kima which are the very strength of Kima...Those that say these 100 are gathered together: They are the strength of the cluster Kima."

Obviously, if 100 stars are the Pleiades' "strength", then the entire Pleiades are much more than 100 stars. Hence, Rashi believed that one group of 7 visible stars were really a cluster of hundreds that could not be seen by the naked eye. How much would the entire milky way or universe contain according to Rashi? TY