Our moon had a great status from the beginning of human civilization, it was immortalized
by various religions all around the world.
In greek mythology there was a moon goddess named
Selene the daughter of the Titans Hyperion and Theia, it was worshiped and respected
the same way as the sun god Helios which indicates
that our ancestors placed the moon and the sun on equal footing.
Moon is also worshiped in Hindu mythology by those who have
fluctuations in their life, ups and downs and by those who wish to have sons.
The moon is featured in Van Gogh’s masterpiece “The
starry night” , Frank Sinatra’s delightful song “Fly me
to the moon” and many other captivating art works.
Art and history have always been enchanted by the moon but today we intend to highlight
the important role of the moon in elevating our
civilization from a scientific perspective.
Our aim is to answer the question “ what would happen
if the moon disappeared?
“
Before answering that question here are some facts about the moon:
1- The moon is the nearest and brightest celestial object orbiting the Earth in an elliptical
path.
It may not follow the same path every cycle due
to the fact that its orbit orientation is not entirely
fixed in space but rotates over time resulting in precession and inclination.
Its apparent size differs from the actual size due to the relative
motion to an observer on the earth, you can understand this as follows, the nearer an
object to you the bigger you will see it.
2- The moon was formed 4.51 billion years ago approximately after 60 million years of
the entire formation of the solar system.
There are several models regarding the moon formation but the
prevailing model is that the Earth-Moon system was formed due to an extremely huge impact
between a Mars sized celestial body called Theia and the proto-Earth, which is the earth
at its very early stages.
The impact resulted in the Earth with its shape today and some other material
in its orbit which accreted and formed the moon.
3- Like the earth, the moon is a differentiated celestial body that can be divided into crust,
mantle and core.
The Core is solid with a molten iron boundary around it, the mantle is the
largest layer formed by a complex yet extremely important process called the magma fractional
crystallization.
The geo-chemical mapping of the moon rocks collected by the Apollo mission
suggests that the crust is mainly composed of mafic minerals which are rich in magnesium
and iron.
4- The photodecomposition process prevents the formation of water on the lunar surface.
In other words, the photons radiated by the sun
decompose the water molecules formed on the lunar surface.
After knowing some interesting facts about the moon and how it was formed, It’s time
to consider the main question of today’s episode.
1- You may wonder what is exactly the relation between the moonlight absence and the
disturbance of the ecosystem because at the first glance they may seem completely unrelated,
however they are strongly connected.
The ecosystem is by definition a biological community of
interacting organisms and their physical environment, it contains biotic and abiotic parts; the
biotic parts include all the living organisms whereas the abiotic components include the
environmental factors such as rocks, temperature and humidity.
According to the encyclopedia of national geographic, every factor in the
ecosystem depends on every other factor either directly or indirectly and the slight disturbance
in one factor will end up affecting the whole ecosystem; for example the change in temperature
of an ecosystem will limit the type of plants that grow in there and hence will affect the
animals that depend on these plants as a primary source of food and shelter leading them to
adapt to that change or move to another ecosystem or perish.
Another important and related concept to highlight is the food chain; which describes
how energy and nutrients move through an ecosystem.
In the food chain, energy is transferred from one living organism through another in
the form of food.
There are primary producers such as plants, primary consumers such as animals
that depend on plants as their food source and
secondary consumers such as predators and decomposing organisms.
The moonlight is considered an extremely important factor in
the ecosystem; according to a study published in
the journal of animal ecology, the absence of moonlight will suppress the activity of
prey species that use vision as their primary sensory system
and increase the activity of those who use other
sensory systems such as olfaction or echolocation.
Think of it as follows, the predators that use
vision such as lions and owls will not be able to hunt during the night in the absence
of moonlight, however the olfactory predators
who are attracted to scent such as foxes, cats and
snakes will still be able to hunt.
This disturbance in the food chain will eventually lead to an
irreparable loss of the ecosystem balance.
2- Tides are waves with extremely low frequency hence, with very long periods, that move
across the oceans as a response to the gravitational pull exerted on the earth by the sun and
the moon.
That gravitational pull generates some force that’s called the tidal force which in turn
makes the oceans water to bulge outward creating points with low and high tides.
The sun has the same tidal effect on the earth’s water
as the moon does however; the total tidal force
generated by the sun gravitational pull is about half of the lunar tidal force and that’s
because the sun is further away from the earth and
as we have mentioned before the moon is the nearest celestial body to the earth.
Therefore, the tidal force exerted by the moon is the primary
cause of ocean tides.
But it’s important to be aware of the fact that the sun can enhance or
detract from the moon’s tidal effects.
That’s because the sun and the moon do become in
alignment with the earth at some points when the moon is full or new, and as a result to
this alignment the whole sun’s tidal force is
added to the moon’s tidal force making the high tides
very high and the low tides very low.
These tides are called the spring tides and they occur
twice a month.
For the first and third quarter phases of the moon, the sun and the moon are not
in line with each other making the sun’s tidal force retracted from the moon’s tidal
force.
Therefore, the tidal effect is less in these quarters and again the high tides will be
less higher and the low tides will be lower, these tides
are called neap tides.
To recap, the moon’s gravitational pull and the rotational force
of the earth are the main causes of high and low tides;
the gravitational pull of the moon makes the water on the nearest side to bulge out as
a high tide but the rotational force of the earth
on the other side is greater than the moon’s gravitational
pull making the water to pile up as it resists the pull of gravity in a form of a high tide
too.
There’re low tides elsewhere; the area connecting the low and high tides is called the intertidal
zone.
That area is alternately covered and uncovered by the ocean’s water throughout the
entire day.
There are microorganisms that live in the intertidal zone; they also depend on the
tidal currents to move across the oceans, the entire ocean’s ecosystem depends to
a great extent on these microorganisms as a primary
source of food.
Now imagine the oceans without tides due the absence of the moon gravitational
pull, there will be a great disturbance of the
ocean’s ecosystem due to the food chain damage leading the entire marine life to perish
eventually.
3- Ocean tides are considered a great source of power in the regions with extreme tidal
variations such as the River Rance in France and Nova Scotia in Canada where they’ve
already built power plants that harness tids as a
source of energy.
Without the moon there would be no gravitational pull to generate these tides
and they would no longer be a promising source of
renewable energy.
4- Earth’s atmosphere is subject to the same tidal forces as the oceans’ water;
these fluctuations in the atmosphere are called
the atmospheric tides.
Which contributes to the upper and lower flow of the temperature through
the atmosphere and this makes some regions' climate dependent upon the moon’s position
in its phases relative to the earth.
The moon absence will be considered as a climate changing
factor in these regions; pretty much as the greenhouse effect.
5- The oceans’ tides themselves are considered to be weather changing factors, since the
ocean is considered to be a heat reservoir that is, the heat intake is constant, the
only constantly changing factors are the tidal
currents and they help distribute the temperature across the oceans.
In other words, tides affect the movement of ocean currents which in turn
affect the weather by the amount of temperature carried by the moving water through a given
area.
According to a paper published in the journal of royal astronomical society of Canada and
named “the moon and the weather”, Gales of wind are remarkably prevalent in Torres
Straits and the neighbourhood about the time of new
and full moon.
This was noticed by Dr.Rattray, a surgeon in the navy, in connexion with observations
made by the surveying ship, Fly, during the three years 1841-44.
Dr.Rattray noticed that at those times there was a large area of coral reef
uncovered at the very low water of the spring tides, extending out some 60 or 70 miles from
the land.
This large area becomes heated, and the great heating of that large portion of land gives
rise to gales at the full and change, that is, at the new and full moon.
6- One of the most important effects of the Moon is that it helps stabilize the rotation
of earth.
When earth rotates, it goes backward and forward as it spins with some variations in its axial
tilt.
The earth axial tilt is 23.4 degrees but it fluctuates between 22.1 degrees to 24.5 degrees
over a 41,000 years period.
These axial fluctuations would vary drastically without the moon.
As a result, the earth would wobble much more and
eventually leading to potentially strong climatic effects.
You may understand that as follows, without the moon as a tilt stabilizer, the earth tilt
would reach 90 degrees, that is the equator would replace the north and south poles; imagine
Africa being covered in ice at some intervals.
This would result in far more extreme variations between temperatures and daylight throughout
the year.
At other times, the earth’s axis would be straight up and down making night and day
equally long and there would be no seasons, they would just be long periods of extreme
weather and huge differences between winter and
summer.
According to Kaare Aksnes, a theoretical astrophysicist, a good example of this is
Mars, which has no large moon to stabilize it so it tilts more.
The martian climate and atmosphere have undergone enormous changes
in the past millions of years, we probably would see something similar to that here.
In conclusion, without the moon there would be one third of the ocean tides due to the
sun gravitational pull and as a result the marine
life will be severely disrupted.
There would be shorter days due to the lack of the tidal
friction which slows the rotation of earth.
There would be a huge impact on the weather and the general
climates on earth, not to mention that we would
be more vulnerable to a shower of asteroids that was soaked up by the moon everyday,
threatening numerous species due to the impact of collisions.
Without the moon we probably would not evolve to the same level as today
or even survive!