We're all pretty familiar with the way that Rosh Chodesh worked in the times of the Temple... two men would go to a court in Jerusalem and testify that they saw the cresent of the new moon. After examination, the court would announce that the day is Rosh Chodesh (the first day of the new month).However, for those of us who aren't seasoned astronomers, we really have little idea what it means to see the new moon. Most of us don't even notice it until a day or two after the molad, as a thin crescent in the western sky at night shortly after sunset.
But what does the moon look like shortly after the molad? How difficult is it to spot the moon after the molad?
Well, here's an answer:
This photo (taken by Laurent Laveder) shows the moon a mere 15 hours and 38 minutes after the molad. Finding the cresent when it is less than 24 hours is very difficult and requires planning. This is the youngest moon that Laveder has ever recorded. As you can see from the picture, it is very difficult to spot the new moon (it is the barely-visible cresent above the dark cloud in the center of the picture). This is what the witnesses went looking for when they scanned the skies in order to give testimony about the new month.