Our Gemara on Amud Aleph recounts a story where Rabban Gamliel, who frequently journeyed on the sea, was informed by Rabbi Yehoshua about “a star that rises once in seventy years and misleads sailors.”
It is fascinating to note that the Rabbis apparently knew about Halley’s Comet. While this is indeed impressive, it is possible that the Babylonians also knew about Halley’s Comet, as they were sophisticated astronomers. Keep in mind, if an astral phenomenon happens once in 70 years, to notice it and its significance probably takes generations of meticulous record-keeping. Regardless of whether the Rabbis observed this phenomenon themselves by their own study and star charts or respected the scientific study and discipline of the Babylonians, it is impressive.
On the topic of science, astronomy, and Rabban Gamliel, there is another interesting story found in Eiruvin 43b:
Rabban Gamliel had a special tube through which he would look and see a distance of two thousand cubits on land, and also determine a corresponding distance of two thousand cubits at sea.
At first glance, this sounds like he had a telescope. However, that would be unlikely, because it is pretty clear that they did not possess that technology. More likely, it was some type of sextant used by sailors for orientation. The Mishna Keilim (30:1) refers to an object called an Ispaklaria (you can see the Greek roots in English words such as spectator or spectacle). Tosafos Yom Tov suggests that it is a telescope, based on his reading of Rambam’s commentary on the Mishna. However, Rambam could be understood more simply as some type of transparent or translucent lens that distorted the image somewhat but one could still see something reflected. Regardless, most commentaries interpret Ispaklaria as a mirror. Yachin (ibid.) has sharp words for anybody who believes this was a telescope. He dismisses it as ludicrous and goes through a history of various optical devices, when they were invented, and who invented them, stating that neither the Gemara nor even the Rambam ever saw a telescope.
This is a story about being careful not to project our current scientific knowledge onto past science without careful analysis, while on the other hand also being open and impressed at the degree of scientific knowledge our sages possessed.
Translations Courtesy of Sefaria, except when, sometimes, I disagree with the translation
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Rabbi Simcha Feuerman, Rabbi Simcha Feuerman, LCSW-R, LMFT, DHL is a psychotherapist who works with high conflict couples and families. He can be reached via email at simchafeuerman@gmail.com