How has the moon transformed our evolution?

Subject : GEOGRAPHY

Section: Physical geography

Context:

Chandrayan-3, India’s moon mission which was launched on 14 July 2023, has set high hopes for India expecting its first moon soft landing.

Moon’s impact on Earth:

Moon, the satellite of the Earth with an orbit of 384,400 kilometres, has a profound impact on lives on Earth.
Though the Moon’s gravitational pull is weaker than Earth’s, it is responsible for Earth’s current length of the day, stable seasons and tides.
The big tidal ranges have been responsible for forcing bony fish into shallow pools on land, prompting the evolution of weight-bearing limbs and air-breathing organs.

Tides:

The biggest impact that the moon has on life is through tides.
The tides resulting from the gravitational force of the moon affect animal life in the intertidal zone, where the ocean meets the land between high and low tides.
- Weaker tides due to the absence of the moon would have narrowed down this zone, increasing the competition for survival among the species.
Billions of years ago, when the moon was closer to the Earth, extreme tides used to occur frequently because the Earth was spinning more rapidly. The tides eroded the coastal areas, adding minerals to the oceans which have been essential for life to evolve quickly.
Tides led by the moon also affect the reproductive cycles of marine life, where the laying and hatching of turtles’ eggs depend on the timing of tides.

Lunar cycles affecting reproduction in animals:

The reproductive cycles of many marine creatures are closely synchronised with lunar phases’, including migration and spawning in fish, crabs and triggering in plankton by the moon’s glow.
Circalunar rhythms, which are tied to lunar cycles affect different types of organisms.
The Moon is essential to migration and navigation, particularly for birds.
The sleep cycles of the ‘pre-industrial communities’ were strongly influenced by lunar activity.

Climate change and stabilising seasons

The absence of the moon would lead to extreme climate change.
There would be huge differences between temperatures and daylight throughout the year, and ice ages would hit different parts of the world every few thousand years.
The moon’s gravitational pull helps transport heat away from the equator and towards the poles, fundamentally shaping Earth’s climate.
Moon also stabilises the Earth’s rotation on its axis by slowing Earth’s rotation on its axis.
In the absence of the moon, the poles would be burning hot and the equator freezing cold, seasons would be a thing of the past, and night and day would be equally long all year round.

Light of moon:

Just like the planets, the moon does not emit its own light but shines due to the reflection of the Sun’s light.
Fluctuating light levels by the moon have a startling impact on life on Earth. The ability to see and to be seen enhances in the moonlight.
Studies have documented changes in the success rates of predators and foraging patterns of prey animals due to this added nighttime illumination.
Studies have shown that lions are less likely to hunt during the full moon and lion attacks on humans happen 10 days after the full moon.
Many bats will be less active during the full moon.
Coral and certain species of crabs, worms and fish can sense the moonlight from particular phases of the Moon. They use this as a trigger to start species-wide reproduction.
Nocturnal animals behave differently depending on where the moon is in the sky during its 29.5-day cycle. When the moon is full and bright, prey fish stay hidden in the reef, when they’d be most visible.

Tectonic plates, water distribution:

Planetologists at the University of Münster (Germany) have shown, for the first time, that water came to Earth with the formation of the Moon some 4.4 billion years ago.
The moon was formed when Earth was hit by a body called Theia.
Researchers from Munster proved that Theia came from the outer solar system and delivered large quantities of water to Earth.
According to scientists, the collision that led to the formation of the moon provided sufficient carbonaceous material to account for the entire amount of water on Earth.
The moon’s pull of gravity might have set our tectonic plates.
It raises the level of the world’s oceans towards the equator. Without this gravity, the oceans would redistribute, raising levels at the poles.

About Tides:

Tides can be defined as the alternate rise and fall of ocean water. It is caused by the combined effects of :
- The gravitational force exerted on Earth by the Sun
- The gravitational force exerted on Earth by the Moon
- Rotation of the Earth

Neap Tide:

When the Sun and Moon form a right angle, as when a half moon can be seen, their gravitational pulls fight each other and one can notice a smaller difference between high and low tides. These are called neap tides.

Spring Tide:

When the Moon, Earth, and Sun fall in a straight line, which is called as syzygy (siz-eh-gee), the greatest difference between high and low tide water levels can be observed.
These spring tides occur twice each month, during the full and new Moon.
If the Moon is at perigee, the closest it approaches Earth in its orbit, the tides are especially high and low.