Exposition concerning the Jewish Hexapterygon for the year 6943 from the beginning of the world is given by Michael Chrysokokkes, notarios of the Great Church. This treatise is a Byzantine adaptation of the Jewish astronomical treatise called Shesh Kenaphayim, the Six Wings, composed by Immanuel Bonfils for the town of Tarascon (Southern France) around 1350. Michael Chrysokokkes’ treatise, written in 1435, is the first example of the fashion for Jewish astronomical tables in Byzantium. Jewish astronomical tables, which – in their Byzantine form – were only devoted to the calculation of syzygies and eclipses, immediately met with great success. The success of Jewish astronomy in Byzantium raises many questions. How does one explain this sudden interest of Byzantine intellectuals in Jewish astronomy, and more generally in Jewish science and philosophy? The contacts between the various Romaniote Jewish communities (whether Karaites or Rabbanites or some other sect) and Byzantine scholars are difficult to trace.