I’m over the moon to be answering today’s question.
In fact, it’s sending me positively loony.
Sorry I shouldn’t wax on should I, your concentration is probably wane-ing...
Enough enough enough.
No more terrible puns.
That was a bit of a rocky start…no awful.
This film is all about our nearest celestial neighbour.
None other than Luna, our very own natural satellite, the moon.
It’s the Earth’s constant companion, orbiting our planet once every 27.32 days, its phases
marking the passage of the months.
But is the moon any more than just a very rough calendar?
Do we really need it, and would we miss it if one day it just wasn’t there?
Well, there’s half a chance that we’d notice it was gone after a few nights.
Because thanks to the reflected light from the sun, a full moon can give enough light
to see by at night.
So without it, we’d be left with much darker skies than we’re used to, which is bad news
for getting around without a torch, but great news for stargazing.
Without that bright disk of the moon over-saturating our eyeballs, we’d have spectacular views
of the milky way right through the month.
However, this moonless life wouldn’t spell a life of leisure for the many species of
animals that rely on the phases of the moon as a pacemaker for their biological clocks.
Like Acropora corals, who time their simultaneous release of sperm and eggs to a precise one
or two days a year, when a full moon appears in the sky just after sunset.
Or the streamlined spinefoot fish, which all choose to spawn during a waning quarter moon.
Losing the moon would play havoc with these reproductive cycles and the species that rely
on them, potentially leading to their extinction as they fall out of sync.
And it’s not just the light of the moon that animals rely on, but also the effects
of its gravity as it progresses on its cosmic journey.
Despite being only 2% of the volume of Earth, and four hundred thousand kilometres away,
22 billion cubic kilometres of cratered moon rock still has enough of a pull on earth and
its oceans to create our tides.
Now, I’m sure this is one of the very few things you remember from geography classes
at school.
Along with oxbow lakes, right?.
But let’s recap.
Tides form as huge masses of water are pulled towards the moon, creating a bulge on the
side facing it.
On the other side of the Earth, the moon’s gravity isn’t so strong, so the water THERE
gets left behind, creating another bulge.
Every day, most coastal areas witness two high tides and two low tides as the earth
rotates, allowing these bulges to circumnavigate the globe.
No more moon would mean much smaller tidal bulges, since the distant sun would be the
only body pulling on the seas.
Therefore, the water would settle to create new, barely varying coastlines.
Now, while most of us might feel a bit nostalgic for the loss of the tides, it’s a bigger
deal for all of the animals, plants and human cultures that depend on them.
Intertidal zones are the bands of land along every coastline that are submerged and then
exposed by the tides on a daily basis, and they are an important habitat for organisms
that like both the wet and the dry, like barnacles, mussels, crabs, sea anemones, seaweeds, and
many starfish.
But the moon may be even more important than that.
There’s evidence to suggest that not just intertidal creatures, but all of life on Earth,
might owe its existence to our friendly rock in the sky.
Four and a half billion years ago, when the Earth was newly formed, scientists think that
it span on its axis at an alarming rate.
Days would have lasted six hours, and the resulting Coriolis forces would have left
the surface battered with intense winds and storms.
But this all changed when another planet smashed into our early Earth, breaking off a bunch
of bits that together formed the Luna we now know and love
With our orbiting moon in tow, the Earth experiences something known as tidal friction, where some
of the Earth’s rotational energy is lost as the tidal bulges move around the planet.
It’s a small effect, but over billions of years, it’s been enough to slow the Earth’s
rotation so much, that it now takes four times as long to spin all the way round.
That means day and night cycles are a comfortable length and weather systems are no longer terrifyingly
strong.
Longer days have made our world a much more hospitable place, and that’s thanks to the
moon.
Incidentally, this tidal friction thing is still going on, and the length of our day
continues to increase at a rate of 2.3 milliseconds per century.
In a million years from now, days will be an hour longer.
Which means an extra hour in bed!
Nice one moon!
But it doesn’t end there…The orbit of the moon is also critical for maintaining
habitable conditions worldwide.
At the moment, our planet’s axis of rotation is tilted at a comfortable 23 and a half degrees,
meaning we have pleasantly moderate seasons.
But a planet’s tilt has a tendency to change as rotating planets are affected by other
massive objects in the solar system.
If the axis becomes too horizontal, the Earth will literally be spinning on its side, and
a Northern Hemisphere winter would see all of Europe, Asia, and North America plunged
into a cold darkness for many months at a time.
Meanwhile, the south pole would see soaring temperatures as the sun remains high in the
sky for weeks.
Such massive temperature fluctuations are certainly not conducive to life, so we can
thank our lucky stars that we’ve got our moon, whose orbital path seems to steady the
planet’s axial tilt – stopping it from ever straying too far, and keeping conditions
within comfortable limits.
So do we really need the moon?
Well, none of the other nearby planets have one like ours, but then, they don’t have
life either.
Just saying.
Are you loony for the moon?
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well in the comments below.
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I would be over the … oh no I’ve used it, i’ve run out of moon puns!