I see that Muslims in France have adopted an astronomical start to Ramadan, rather than believe their eyes on that first crescent moon in the western sky.
Muslim scientists have been arguing for using astronomy to determine Islamic dates for years, especially now that globalized communications make it increasingly awkward for different countries to start Ramadan on different days.
I wasn’t aware that this was a problem. Arabs were at the forefront of the science of astronomy through most of the European Medieval period. Many dozens of stars have Arabic names that predate their modern designation of Greek letter plus Latin constellation name.
I wonder what Muslims will do when they leave the Earth and travel to planets with more moons or none. Will the Earth calendar be followed from a distance? Will Muslim councils determine a different method from the lunar calendar?