One might think that the long shadow is because of the central peak of Arzachel (1.5km high) but in fact it is a tribute that I want to pay to Arzachel and what the naming of these two craters (Arzachel and Alphonsus) represent and their close relation to Astrobin.

Please be warned, a long (and thrilling😊 ) text is ahead of you and only the last paragraph will be about the Astrophotography details of the image.

If there is one field of knowledge addressed and pushed forward by all civilizations and peoples in the world/History that is Astronomy. Moreover, on many occasions this knowledge has been built on the advances and beliefs from other civilizations and cultures.

This fact brings us to this image, Arzachel and Alphonsus, I don’t know who was the genius to name these two craters together, and close to Ptolomeaus and Albategnius (not visibles on the image), but he/she nailed it. As they represent a perfect example of this sharing and transfer of knowledge across cultures.

Al-Zarqali was born in Cordoba in 1029 (in Al-Andalus, what today is Spain). In latin world he is known as Arzachel (in Spanish is known as Azarquiel). He belonged to a family of craftsmen and after moving to Toledo (under Islamic power at that time, being a Taifa) he entered the service of its king al-Mamun. There, he started to develop scientific instruments as astrolabes for the Arab and Jewish astronomers of the kingdom. This interaction and his own capability allowed him to not only evolve the astrolabe (with the azafea, also called universal astrolabe, which allows to make observations from any Earth latitude) but also to write several books on astronomy and astronomical instruments.

Among them the two most famous are the Toledan Tables and the Almanaque. The Toledan Tables deal with various aspects of astronomy, like the determination of the right ascensions, the equation of sun, moon and planets, ascendant, parallax, eclipses, the setting of planets, theory of trepidation, tables of stellar positions, trigonometrical tables etc.

Interestingly, he based a significant part of his work on Ptolemy, al-Battani and Al-Juarismi (Algebra and Algorithm derived from his name), correcting geographical data from them.

Toledo came under Christian rule in the mid-1080s, shortly after the tables were completed. A century later at Toledo, the Arabic-to-Latin translator Gerard of Cremona in the 12th century translated for Latin readers the Tables of Toledo, the most accurate compilation in Europe at the time, and contributed to the rebirth of a mathematically based astronomy in Christian Europe and were later incorporated the Alfonsine tables in the 13th century.

And here is where our second crater comes into play. The Alfonsine Tables, also spelled Alphonsine Tables, were the first set of astronomical tables prepared in Christian Europe. The work was prepared in Toledo for King Alfonso X of León and Castile under the direction of the Jewish scholars Jehuda ben Moses Cohen and Isaac ben Sid. At that time, King Alfonso X gathered a significant bunch of astronomers and scholars, Aben Raghel y Alquibicio and Aben Musio y Mohamat, from Seville, Joseph Aben Alí and Jacobo Abenvena, from Córdoba, and fifty more from Gascony and Paris.

After a Latin version was prepared in Paris in the 1320s (the Alfonsine tables were originally written in Castilian Spanish), copies rapidly spread throughout Europe, and for more than two centuries they were the reference astronomical tables. First printed in 1483, the Alfonsine Tables were an important source of information for the young Nicolaus Copernicus (he bought a copy while at the University of Cracow) before his own work superseded them in the 1550s.

When I saw the long shadow from the central peak of Arzachel I couldn’t avoid smiling at the analogy with the life and work of Arzachel and the closeness with the Alphonsus, Ptolomeaus, Alpetragius and Albategnius. And how much this closeness represent these knowledge transfers and incremental collaborative work across so many different cultures (Greek, Arab, Jewish, Christian,…) and geographies.

Which leads us to Astrobin, where a community of people of many different cultures and geographies exchange the joy they experience interacting with the Universe by capturing and sharing the photons it delivers on us. I cannot avoid seeing a resemblance of the long History of Astronomy in this community (even though the purpose is not scientifical nor some of us are scholars/researches). In this sense, I want to express my gratitude to this community (all of you) and to Salvatore for keeping “History” rolling.

I almost forgot about the image!, it is 3% selection of 43000 frames at about 140 fps. Results processed with lightroom, astra image and pixinsight. I have not prepare a process chart as with last images, as this one is more about the story than the technical processing. Seeing varied during the capture and wind “jumps” warned me to preprocess it with PIPP (I do not why it works better when is very shaky) before Autostakkert.

I hope that the reading was worth it (and fluent and without many mistakes), and that it helped you to see this part of the Moon with different eyes next time, as well as us as a community! Take care, Guillermo.