ELI5. I’ve always been told moonrise for a new moon is around dawn and for a full moon around sunset, but also that it takes about 29.5 days for the lunar cycle. Are both these true? Shouldn’t the new moon rise around dawn one month and then around sunset the next month?
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The moon’s position relative to the sun determines when you can see it and what it looks like.
A new moon occurs when the moon is between Earth and the Sun. A day or two later the moon has advanced far enough so that at sunrise the moon has not quite risen. Daylight blanks out the moon sliver. Only after the sun sets in the evening while the moon sliver is still above the horizon, and does the new moon become prominent in the dimming sky.
Before the next new moon, the moon has traversed the whole sky and arrives at the sun again from the east. So in the morning just before a new moon, the moon rises just before the sun while the sky is still dim. The next day, the moon is pretty much lined up with the sun: another new moon.
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