In 1911, astronomer Walter Maunder in the Journal of the British Astronomical Society ( v. 21, p. 355) compared visibility observations from 42 observations around the world. He found that half of the naked eye detections occurred when the Moon was about 24-30 hours old. Only 11 detections occurred for a First Crescent younger than 20 hours old, and only 5 for a Moon less than 18 hours old. Under the right conditions, and knowing exactly where to look in advance, a 19 hour-old Moon is moderately difficult to spot in the glare of twilight, it is only about 10 degrees from the Sun. Recently an amateur astronomer, using a pair of binoculars, a tripod mounting and a bit of hard work and luck, detected the slim crescent of a 13.5 hour Moon!