Possibility for Melburnians to make a rare sighting of an infant, 18-hour-old, lunar crescent
The New Moon of Sunday, 8 August, 2021 is a highly significant one for Melburnians. It will occur at 23:50, AEST. On the following day, Monday 9 August, sunset at Melbourne is 17:39, at which time the Moon will be just under 18 hours old, and moonset at Melbourne that evening will be just 33 minutes later at 18:12. This confluence of events affords Melburnians a rare opportunity (weather permitting) to make an exceptional astronomical observation: the sighting of a very thin, infant lunar crescent, having just attained the minimum distance east of the Sun (usually said to be 9°) required for such a sighting to be possible. The rate at which lunar elongation increases is about 0.5°/hr, which means that, at the above speed, lunar elongation should just reach 9° just after sunset at Melbourne. (On that Monday, the Moon will be about halfway between apogee and perigee, so moving at about its mean orbital speed.) I urge everyone who can to keenly watch the western sky that evening, if it