– As viewed from anywhere on Earth, a first quarter moon appears at its highest in the sky at sunset. It sets around the middle of the night.
– It’s called a quarter moon, but, from Earth, it looks half-illuminated, like half a pie. Or you might say that – at first quarter moon – we’re seeing half the moon’s day side or a quarter of the whole moon.
Quarter moon? Half moon?
There’s another reason we call this moon a quarter and not a half. It’s because it’s one quarter of the way around in its orbit of Earth, as measured from one new moon to the next.
Bottom line: The first quarter moon occurs halfway between new moon and full moon. One quarter of the moon is visible from Earth, meaning that you see half the daylit side of the moon, looking like half a pie.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.
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