What is the length of day and night on the moon?

Yes, there are nights and days on the moon, but the time for each period is not the same as the ones on our planet. Instead of the twenty-four hours length of a normal day on Earth, a day on the moon is equal to 27.3 earth-days because the space object takes so much time to complete a rotation around its axis. What is more surprising is that the moon takes basically the same amount of time to complete a circle around the Earth too, which is approximately 27 days, 7 hours, 43 minutes, and 12 seconds. As a result of its slow rotation, we often just see only one side of the moon. It is said that only 59% of the moon’s surface is visible from us and the Earth, with 41% of the surface never seen by us unless we travel there and see the “dark side of the moon.”

Furthermore, the moon only has a day and a night, and it has no evening or even afternoon! The reason why this phenomenon is present is that there is no atmosphere on the moon. Due to the absence of oxygen or air on the moon, the rays of sunlight do not scatter before it reached the surface at all. As such, when the sunrays do fall on the moon’s surface, it will shine like a blinding light, and the rest of the surface that doesn’t get even a glimpse of sunlight is extremely dark. The phenomenon creates the moon’s peculiar appearance, wherein both the sunshine and the darkness are divided by a straight line at the middle of the moon’s surface. It could also be argued that without air, the climate is also not quite temperate or balanced on the moon. The temperature of the surface that gets sunlight would be around 102°C, whereas the surface in the dark side of the moon has a temperature that would drop down to freezing -157°C.

The time that one side of the moon’s surface gets sunlight varies, as the moon doesn’t really have a stable rotation. This imbalance in the moon’s rotation may be caused by the differences in orbital velocity and the influence of gravitational perturbations between the Sun and the Earth. The disturbances refer to the phenomenon wherein the moon is being pulled by the Sun’s gravity in a specific location, causing the Earth to lose its grip on the moon for a relatively short period of time.

Because of this unstableness, the sun rays would usually produce daylight on only one side of the moon’s surface for two weeks, and then that same side would lose the sunlight for about two weeks as well since the moon has already rotated at its axis.

There are also alternative uses to the term “lunar day,” and most of these usages are referring to the days on Earth and not on the moon. A lunar day can sometimes refer to the period between high moons, which are the time where the moon rises slightly higher than usual. A high moon is said to last 50 minutes longer than a typical day on Earth. Another use for the lunar day is for the opposite of lunar night. Both lunar nights and lunar days are used to determine the number of days that a rover or a spacecraft is situated on the moon, and it also indicates the temperature on the area where the vehicle is located. One lunar day is equal to two weeks on Earth, and the temperature on that period is warmer than in the lunar night.

The lunar calendar also uses lunar days to refer to how the sunlight affects the appearance of the moon from the Earth. These appearances are called the lunar phases, and these were once used to determine the day for ancient civilizations. The most used named for several lunar phases are new moon, crescent moon, half-moon, and full moon. The lunar phases would change depending on the location of the moon and the amount of light that it receives from the Sun. In addition, the lunar phases are also utilized to determine the day and night on the moon before the calculation of its rotation and orbit.