While gone are the days when the moon was widely considered a divine entity, common knowledge of our planet’s companion in space is rife with misconceptions. Several people still do not comprehend why we observe different lunar phases throughout the lunar cycle, which lasts around 29 days, or why the familiar celestial body orbiting earth has its tell-tale pockmarked appearance.

A passive observer of the skies will soon realise that the moon always appears to display the same side from our perspective here on earth. This phenomenon occurs because the moon is tidally locked with earth, meaning that it orbits our planet such that it completes one full spin on its own axis in exactly the same time it takes to complete one orbit around the earth. As a result of this, even though the moon is effectively spinning, it takes around 29 days to complete one spin and therefore we always see the same side of the moon from earth.

This has led to the coining of the phrase ‘dark side of the moon’, referring to the side we do not see from earth. This phrase alludes at the misconception that the side of the moon we do not see is always dark, as opposed to the lit side we see. In reality, however, each part of the moon’s surface is lit for approximately equal periods of time. Like the earth, half of the moon is lit by the sun and half of it is in darkness at any point in time. As it orbits the earth, we see more of the lit or dark sides accordingly, depending on where the moon is in relation to earth.

If the side of the moon facing earth is only slightly lit, we call the moon a crescent, while if it is mostly lit, we say it is gibbous. When the moon is in crescent phase, a substantial part of the farther side of the moon is also lit. At quarter phase, half the near side and half the far side of the moon are lit, but we only see the half facing earth. A full moon represents the only time when its near side is fully lit and its farther side is completely dark. However, fast forward around 14 days, and the exact opposite happens. The farther side of the moon, not visible from earth, is completely lit and the side facing earth is in complete darkness. This is referred to as the new moon phase.

Dark side of the moon? Myth debunked!