Moon phase names
What are the moon phases called?
Eight names, in order: new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, waning crescent — and back to new, about 29.5 days after the last one. The words are a small dictionary: waxing is growing, waning is shrinking, a crescent is less than half lit, and gibbous — “humped” — is more than half. The four in-between names describe shapes; the four turning points (new, first quarter, full, last quarter) mark quarters of the journey that causes the shapes.
Why “first quarter” looks like a half
At first quarter you see a half-lit disc, and the name is still right — it counts the orbit, not the light. The Moon is a quarter of the way around its lap when we see half its lit side. The names track the journey; the shapes track the lighting. Once you know that, “last quarter” stops being confusing too: three-quarters of the way around, the other half lit.
How to read tonight’s moon
Two questions identify any phase: how much is lit, and which side is lit. Less than half is a crescent, more than half is gibbous. North of the equator, a moon lit on the right is waxing — heading toward full — and lit on the left is waning; south of the equator the two swap, because you are looking at the same Moon the other way up. Your town’s moon page names tonight’s phase and the 30-day strip shows the whole run.
The same instant, the whole world over
The phase is the angle between the Sun and the Moon, so everyone on Earth sees the same phase at the same moment — there is no city where it is first quarter while another has full. What changes with where you stand is which way up the shape hangs, and when the Moon rises. That is why phase pages can be global while moonrise pages have to know your town.
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Where the turning points really are
New moon is not “no moon” — it is the Moon standing in the Sun’s direction, its lit half facing away from us, up all day and lost in the glare. Full is the opposite station, and it is the only night the Moon is up from sunset to sunrise. Scrub the simulator across a month and you can watch each name arrive as an angle, not as a picture on a calendar.
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On the hub: Moon