Question:
If I blessed the moon during bein hashemashot (20 or 25 minutes after shkia, while I usually hold that nightfall is 72 or 45-50 minutes at the earliest), was I yotzi?
What about if I had done it even earlier?
Answer:
The time for Kiddush levana is when it is dark enough that the light of the moon is bright. I can’t give an exact time for this as it depends on where you are located and how long it takes for it to get dark in your area.
Sources:
O:CH 426-1 M:B ibid 2
