The Islamic calendar, based purely on lunar cycles, was first introduced in 638 C.E. by the close Companion of the Prophet (SAW) and the second Caliph, Umar ibn Al-Khattab. He wanted to reconcile the various dating systems of his time.

However, the Hijra calendar isn’t just a sentimental system of time reckoning for Muslims; rather, it has a deep religious and historical significance. Moreover, it has had many scientific influences on our daily lives in the areas of psychology, physiology, and the environment.

By returning to the use, or at least the recognition, of the lunar calendar we gain many benefits as Muslims. Muslims recorded all their events in the Hijri Calendar.

The Prophet (PBUH) has said, “Fast at its sighting, and terminate the fast at its sighting” (Bukhari, Muslim). Our use of the Gregorian calendar makes us forgetful of the spirit of these events.

The Qur’an says, “And he has subjected you to the night and day, and the sun and the moon and the stars are subjected by his command.” (Surat An-Nahl 16:12).

Many scientists believe that “subjected” in this context implies much more than simply being the basis for a calendar. Studies have shown that the moon, in fact, influences our moods and physical cycles.

Although most people can’t tell when the new or full moon will appear, these same lunar cycles can provide so much insight into fertility and mood cycles. Some scientists suggest that the effects of the lunar cycle are evident in numerous life forms.

For example, shellfish renew their shells, and undergo regeneration and sexual activity in accordance with the lunar tidal cycle. Guppy-fish have color sensitivity on their back that is most responsive during the full moon. The golden hamster displays lunar rhythms in activity, and urinary volume and acidity.

Moon cycles are well known to hunters and fishermen. Sea creatures show a high lunar sensitivity; their reproductive cycles for instance.

Exact lunar rhythms affect the reproductive cycles of fish. Oysters open their shells at high tide. Shrimpers flock to a full moon, at which time they predictably rise to the surface to feed.

Lunar Impact & Biology

Zoology shows that physical activity, metabolism, aggression, and sexual behavior increase in many species during specific moon phases.

To deny that the moon affects the human species as well is shortsighted; however, many people around the world still feel compelled to debate and research the topic.

One Italian study (Ghiandoni et al, European Journal of Obstetrics, Gynecology and Reproductive Biology, March 1998, vol. 77, pp. 47-50) found a correlation between spontaneous full-term deliveries and the lunar month. It found that the delivery day is correlated with the first or second day after the full moon.

Most importantly, fertility cycles are synchronized with the moon; thus, couples wishing to conceive have the best results when they observe the moon’s cycles rather than solar cycles.

A Russian study (Lucatelli and Pane, Biofizika, Sept.-Oct. 1995) has found a correlation between some types of bipolar manic-depressive syndrome and planetary locations in relation to the lunar month.

Other studies have found large correlations in emotional (including violent) acts around the full moon and a tendency for people to become depressed or introspective during the waning of the moon.

Traditional moon wisdom states that on the day of the New Moon the body’s capacity for detoxification is at its highest.

This is a time, tradition says, to make healthy lifestyle changes, break bad habits and withdraw symptoms of imbalance. This is in complete synchronization with the fact that the prophet used to fast on the days of the full moon, saying, “It is like fasting the whole year.”

The Qur’an says, “It is He who made the sun a shining and the moon as a light and measured out stages that you might know the number of years and reckoning.” (Surat Yunus 10:5). In fac,t the moon is a reckoning for many events. For instance, farmers say, “A circle around the moon means it will rain or snow soon.”

Several Benefits

Scientists say this circle result from the refraction of light through the troposphere’s ice crystals. It’s associated with a thin layer of cirrus clouds.

Often, this layer of ice crystals will precede a developing storm by 24 to 36 hours. Although the circle does not necessarily mean rain or snow, it can be an indicator that there is a chance of precipitation over the next couple of days.

Tradition also says, “If the new moon holds the old moon in her lap, expect fair weather.” Scientists say this is so because, during fair weather conditions, the air is more stable, which minimizes turbulence.

Research has linked hurricanes to full and new moons. Data has also shown that rainfall is more likely to occur at the first crescent than at the first quarter of the moon, and at the disseminating moon phase rather than at the third quarter.

Both the sun and the moon affect our water supplies (all water, including the water within the earth, and not just large bodies of water such as the oceans and rivers) through their magnetic pulls.

Although the sun is much bigger than the moon, the moon is much closer to earth. Hence, lunar pull is greater.

The movement of the moon affect the rising and falling of the tides. Crops planted while water is rising during the waxing moon can more easily absorb water than those sown in the waning phase.

Therefore, we plant crops that thrive in dry conditions during the waning phase. Also, we aboveground crops that need lots of water during the waxing phase.

Certainly, Allah has subjected us to the moon. We would be wise to bear this factor in mind, and keep our Hijri calendar close by our Gregorian calendar at all times.

This article is from Science’s archive and we’ve originally published it on an earlier date.