PLANETARY CYCLES: SUN

I am starting this series on Planetary Cycles and how they affect Growing Food and Human Health, appropriately, as the Earth reaches the equinox.

The sun is overhead at the equator, and day and night are as equal as they get everywhere on Earth, though the exact duration of daylight depends on your latitude. We start with the Sun.

PLANETARY CYCLES: SUN

Planetary cycles influence how life functions, from the unseen life beneath our feet and in our guts to the forests and plains around us to the living world beneath the deepest sea. Each organism follows these cycles in different, interconnected ways.

PLANETARY CYCLES

SUN

Daily Cycle, Yearly Cycle, Seasons

MOON

Monthly Cycle, Fortnights (Circa Semilunar Rhythm)

THE LONG CYCLES

Stages of Life (The Individual Cycle)

Generational Cycles

Solar System & Galactic Cycles

For each cycle, we will explore what drives it, how it affects living things, and how we can work with it in practical ways.

DAILY CYCLE

The sun runs daily life. As the Earth rotates, the side facing the sun is lit, and the side away from the sun is dark. Daylight and darkness set biological rhythms for everything on Earth. As humans, we are diurnal.

Diurnal (Animals)

Organisms that are active primarily during daylight hours and sleep or rest at night, for example, humans and most birds. It is the direct opposite of nocturnal (active at night) and distinct from crepuscular (active during dawn and dusk).

The daily diurnal cycle is a 24-hour loop driven by Earth’s rotation on its axis. It creates the transition between day and night and directly shapes the immediate survival, energy levels, and biology of all living things.

Impact on Plants

Plants rely on solar energy, using photosynthesis to transform light energy (sunlight) into chemical energy (sugars and starches). Nutrients supply matter. Sunlight supplies energy.

Plants are intimately connected to the cycle of day and night.

Photosynthesis and Respiration 

Plants operate on a strict day-night cycle. During daylight, they open their pores to capture sunlight for photosynthesis. At night, they switch to respiration, consuming stored sugars and releasing oxygen.

Diurnal Movement 

Many flowers and leaves physically respond to the changing light of day and night. Morning glories and others open at sunrise to attract daytime pollinators. Some open in the afternoon. Many close at sunset. Moonflowers and other night-bloomers open after dark, attracting pollinators like moths and bats.

Some plants respond not only to sunlight but to its changing position throughout the day. Young sunflowers, for example, track the sun as it moves across the sky, turning their heads from east to west and back again overnight.

Effects on Microbes in General

The daily solar cycle dictates the immediate survival and function of microbes.

Dawn 

Sunlight activates photosynthetic microbes (like cyanobacteria). Their biorhythms capture daylight for energy but divide their cells during darkness to prevent harmful UV rays from damaging their DNA during replication.

Night 

At night, non-photosynthetic bacteria and fungi take over. They use the dark hours to consume stored sugars, fix nitrogen, and repair cellular damage accumulated from the sun’s radiation during the day.

INDIGENOUS MICRO-ORGANISMS (IMO)

The day/night cycle influences the ecology of an IMO culture, which influences its effectiveness.

An upcoming article will cover the subject, including the best time of day to set up the collection, harvest the collection, and the factors affecting the culture being collected, including microbial diversity.

Effects on Microbes in the Soil

Soil microbes live in a highly dynamic boundary zone, making them acutely sensitive to the 24-hour cycle.

Vertical Migration 

Soil bacteria and tiny fungi physically move in response to the sun. During peak afternoon heat and UV exposure, microbes move deeper into the soil layers to find moisture and shade. At night, as the surface cools and morning dew arrives, they migrate back up to the topsoil.

Root-Zone Communication 

Plants push sugars and carbon (exudates) out of their roots into the soil primarily during peak daylight hours when they are actively photosynthesizing. Soil microbes cluster tightly around these roots during the day to feed on this sugar, shifting to a slower, soil-decomposing state at night when the plant’s sugar supply stops.

Fungal Spore Release 

Many soil-dwelling fungi use the daily cycle to time their reproduction. They release their spores into the air precisely during the humid, cool hours of dawn or dusk, using the daily atmospheric transition to help their offspring travel and survive.

Impact on Animals

Animals base their movements and activities depending on their role in the environment and the time of day.

Niche Partitioning 

Animal activity is distributed across the 24-hour cycle, with different species becoming active at different times to reduce competition for resources and exposure to predators. This is referred to as Temporal Niches.

Diurnal animals, like hawks and humans, hunt and forage by day. Nocturnal animals, like owls and bats, take over at night. Crepuscular animals, like deer and most mosquitoes, are active at dawn and dusk.

Thermoregulation 

The extreme temperature shift between day and night forces behavioral changes. For example, desert reptiles bask in the morning sun to warm their bodies but must retreat underground during peak afternoon heat to avoid overheating.

Impact on Human Behavior and Needs

While artificial lighting and other technologies let humans operate at any time of day or night, our biology still strongly affects us, and countering our circadian rhythms can have detrimental effects. Our health depends on moderating our biological needs with modern demands.

The Circadian Rhythm 

Our internal biological clock is entirely tethered to light. Morning sunlight triggers the release of cortisol to wake us up, while nightfall prompts the brain to produce melatonin, lowering our body temperature and preparing us for deep sleep.

Societal Structures 

Human life is universally built around this cycle. Our working hours, eating habits, energy grids, and traffic patterns are designed to maximize daylight productivity and reserve the dark hours for rest and recovery.

Coming next:  

Seasons

How We Can Work with Solar Cycles in Practical Ways