On the night of Sunday the 21st of May from approx 19.00 Hrs – 22.30 hrs above the W – NW horizon

a 4.6% illuminated waxing crescent Moon will offer a favourable lunar libration

that will offer the chance to see the 200Km +  crater Humboldt  located along the bottom of the crescent

this event would be best viewed as the skies darken after sunset from approx 21.00 Hrs

if you plan to observe / image this event remember to dress for the conditions