All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Sighting the moon during the day either before midday or after it is possible, and the moon can also be sighted in the night following that (same) day.
This is a well-known fact and it is up to the astronomers to explain such an event.
In case the moon is seen during the daytime, then such a sighting is considered as a confirmation to it but this sighting is for the following night not the previous one.
Allaah Knows best.