Danjon Limit
Long version:
https://adsabs.harvard.edu/full/1998Obs...118...65F
Short version:
https://lovethenightsky.com/thinnest-crescent-moon/
tl;dr
With one special exception (total solar eclipse) itโs impossible to see the moon with naked eye when it is less than 7.5ยฐ away from the sun, or less than 12 hours old, this is known as the Danjon Limit.
Eid research it is, then... All Arab lands are below the limit according to the map.. So, how are we having our eid tomorrow?
Some juristictions do not follow naked eye sighting. There is a vast permisibility within the madahib of what counts as a valid sighting. Arab lands are all using different criteria so you have Egypt saying no moon was sighted and KSA saying it was. Best to follow your local scholars if you are outside the rule of a muslim government. If you are able it is a beautiful experience to sight a new cresent on your own and brings certainty to your soul.
I mean for sure.. It's my favorite day of the year..
It's just that I never really looked into the technicality of it from a jurisprudence point of view.
