Day and night is the duality we perhaps observe the most and it certainly has a solid set of correspondences in the foundational astrological knowledge — it is at the core of the wheel of the Western astrological chart.

Getting a better understanding of astrology often starts with noticing how opposing principles define the dynamism of the the configuration of celestial bodies of every chart. This facilitates the move from the oversimplifications like “good vs bad” to fluid understanding and deeper interpretation.

Day and Night or rather… Nychthemeron

The English language doesn’t have a word for the 24-hour cycle consisting of the two phases, namely light time and dark time. Many other languages do have a special word for that unit of time. The Greek word “nychthemeron” (literally meaning night-day) is often used to express the full cycle of day and night. It’s a funky word yet useful to keep in memory for those special occasions.

The diagram below illustrates the unfoldment of the day-night cycle which is the basis of the Western astrological chart.

Day and night division is the foundation of the Western chart

Action and rest, diurnal and nocturnal

The day and night phases describe not only presence or absence of light, they also symbolise action and rest. Time itself is divided into alternating phases with the day phase beneficial for action, the night phase — for internalisation.

This inherent dualism is being well expressed by the symbolism of the celestial bodies where each body is associated with either day or night modality, or even both at once.

The Sun is obviously diurnal. It is the source of all light, the life-giving principle of heat and therefore action.

The Moon doesn’t emanate any light by itself but reflects it. The Moon is a nocturnal luminary with its predisposition for rest and moisture.

Jupiter relates to the Sun and therefore it’s diurnal. Even at the physical level, Jupiter is considered to be a star in the making. Watched the film 2010: The Year We Make Contact ?

Venus relates to the Moon and is nocturnal.

It’s also worth remembering the gender principle allocated to the planets: The Sun and Jupiter are masculine; The Moon and Venus are feminine.

Mercury — being transgender (read post “Masculine, feminine and transgender in astrology”) — oscillates between diurnal and nocturnal states. It is considered diurnal when is above the earth when the Sun rises, and nocturnal when sets after the Sun.

A dilemma allocating Saturn and Mars

Saturn is the planet of “coldness”. Mars is the planet of “dryness”.

Using the principle of balancing the opposites, it could be suggested that coldness of Saturn should be used to counterbalance the heat of day. Therefore Saturn is considered to be of a diurnal quality.

Mars with its dryness opposes moisture of the night. Thus Mars is a nocturnal planet.

It is worth noting that this is the classical Ptolemy’s view. One may also argue that Mars stands for action and fits the day much better, and Saturn is mostly being depicted as an aged inhabitant of the twilight zone — which fits the image of the night rather well.

Using this alternative allocation would add “coldness” to “moist” of the night and “dryness” to “heat” of the day. Could it be that this would take the opposing forces out of balance? It’s an interesting question to ponder upon.

Putting it all together

Using Ptolemy’s view the summary may look like so:

Planet Time quality Gender
The Sun Diurnal Masculine
The Moon Nocturnal Feminine
Mercury Diurnal-Nocturnal Transgender
Venus Nocturnal Feminine
Mars Nocturnal Masculine
Jupiter Diurnal Masculine
Saturn Diurnal Masculine

Classifying the zodiac signs

The qualities of time and gender can also assigned to the zodiac signs.

Aries and opposing Libra cusps mark the northern and southern equinoxes (spring impulse in each hemisphere) and thus considered to be diurnal and masculine.

Qualities of the rest of signs distributed in an alternating order.

Interestingly, Cancer and Capricorn are the solstice signs and are said to be nocturnal. Their cusps mark the peak duration of day after which the impulse of the night is emerging.

Day and night principles in the zodiac

It’s not all set in stone

The allocation of dualities of day and night to the planets and the zodiac is an interesting way to classify celestial bodies and sectors of the sky. It makes a certain sense from the standpoint of balancing opposing forces, the hallmark of the universe. Yet there could be other valid models that make more sense under different circumstances. This is the beauty of astrology as a metaphysical discipline — it’s not all black and white!