Quarter Moon

A Quarter Moon looks exactly half-illuminated, which confuses a lot of people expecting it to look like a quarter — but the name refers to its position in the roughly 29.5-day lunar month, not its visual shape. First Quarter marks one-quarter of the way through the cycle (about 7 days after New Moon); Last Quarter (also called third quarter) marks three-quarters of the way through (about 7 days before the next New Moon). Both look identical in shape — a half-lit disc — but face opposite directions: First Quarter is lit on the right in the Northern Hemisphere and rises around midday, visible in the afternoon and evening sky; Last Quarter is lit on the left and rises around midnight, visible in the early morning sky. This is also why "Quarter Moon" without a qualifier is genuinely ambiguous — astronomy sites and calendars should always specify first or last, since they occur exactly two weeks apart and represent very different points in the cycle.