Sidereal Month

A sidereal month is the time it takes for the Moon to complete one full orbit around Earth relative to distant stars. Unlike the lunar month from a human perspective, which is about 29.5 days (synodic month), the sidereal month is approximately 27.3 days. This difference occurs because as the Moon orbits Earth, Earth itself is orbiting the Sun, so the Moon must travel a slightly longer path to realign with the same star. In essence, a sidereal month measures the Moon's orbit against the backdrop of points in space, providing a precise orbital period independent of the Sun’s position.