Understanding first quarter moonPosted: May 10, 2011
Teacher, why do they call it “first quarter moon” but we can see half of it? Shouldn’t we call it “first half moon” or something?
Here’s an explanation from the folks at EarthSky.org:
[We] officially call this moon a quarter and not a half because it is one quarter of the way around in its orbit of Earth, as measured from one new moon to the next. … A first quarter moon rises at noon and is high overhead at sunset. It sets around midnight.