How does the Moon's orbit cause conjunctions to occur twice a month?
Answer
The Moon's orbit is tilted slightly relative to the ecliptic, intersecting it about twice a month.
Conjunctions involving planets are fundamentally tied to the geometry of the solar system, specifically the ecliptic plane, which is the flat path on which all major planets orbit the Sun. The Moon's orbit around the Earth is not perfectly aligned with this plane; it is tilted slightly. This tilt causes the Moon's orbital path to intersect the ecliptic plane roughly twice during each revolution around the Earth. A conjunction is witnessed precisely when the Moon crosses the ecliptic at the same location where one of the planets happens to be situated at that time.
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