Re:Lunar Crater Radio Telescope on the Far-Side of the Moon ...
by dave333 on Wednesday September 15, 2021 @05:14PM
(#28544445)
Sidereal month (relative to fixed stars) is 27.32 days.
Synodic month relative to Earth is 29.53.
There are other months that correct sidereal for motion around the sun, eccentricity of the lunar orbit, and tilt of lunar orbit, but the difference is tiny.
Separately though, the misconception comes from the fact that we have 4 phases of the Moon (new, first quarter, full, last quarter), and it's easy to conceptualize that the interval between two is 7 days, or one week, rather than 7.38264725.