Despite its distance, the moon has a huge impact upon modern day life; from its effects upon ocean tides to its relationship with werewolves. But what would life be like if the moon had never existed? How would things be different? Would the oceans have drowned us years ago or would we simply be a werewolf-free planet in which Neil Armstrong would be left to scrounge the streets?
If these kinds of questions keep you awake at night, as they do me, then you may be relieved to discover that life would, most probably, still exist if our moon had never been formed. However, things would be very different.
It is theorised that about 4.5 billion years ago our moon was formed due to the collision of Earth with a lump of rock the size of Mars. In the process the speed at which our planet spins was slowed, from a rather hectic eight hour day, to our much more relaxed 24 hour day. Almost all multicellular life has adapted to this 24 hour day and it cannot be overstated the huge impacts that this simple change in day length would have had upon evolution over the years. Not just individual organisms, but whole ecosystems would be different, due to the effects day length has upon climate, photosynthesis and sleep.
Another factor which controls our climate and ecosystems is the tides. The tides help spread heat from the equator to the poles, meaning our planet is warm in places it otherwise wouldn’t be. This is all due to the 1020 joules of gravitational energy that is shed into the oceans annually, most of this energy from outer space (and from the wind). While the absence of our moon from the sky would not result in zero ocean tidal energy, it would result in much weaker tides meaning a less rich marine environment and fewer species under the waves.
So the absence of a moon would have altered our day length, our climate and our ocean wildlife. But that’s no biggie right? Surely it wouldn’t have affected the origins of life? Surely little, simple organisms like bacteria would be basically the same? Please tell me that my favourite gram-negative bacterium would still be here? The answer is probably not.
Molecular biologists from ‘Pieta Research’ in Edinburgh believe that our DNA structure is, in part, thanks to the moon and its effects on our tides. Proto-nucleic acids are thought to be the precursors to nucleic acids which are the building blocks of our DNA. Getting these chemicals into the right environment and concentrations to react was, in part, due to the tides. High tides would push chemicals up into the crevices of rocks on the shore. When low tide came, water would recede and evaporate from the rocks, which concentrated the chemicals in a high salt environment. This is one of the ways which scientists think that these chemicals would have been found in high enough concentrations in order to react. Furthermore, the high salt concentrations created upon the rocks would be perfect for proto-nucleic acids to bond and make longer stands, similar to that of DNA. When high tide came again the salt concentrations would decrease and the bonds would break, dissociating the strands. Repetition of this process provides a potential mechanism for some of the first replication events, as it allows nucleotide strands to be formed at low tide, split in two at high tide, and then each of the split strands could form a strand of its own at low tide again.
So, as you can see, the moon has been pretty useful to us over those past few billion years. But what if you want to destroy the moon? Maybe you’re a werewolf who’s fed up of that monthly inconvenience. Or maybe you’re a wanna-be Luke Skywalker who looking for some “small moon” target practice? What would the repercussions be?
As it turns outs the repercussions might be pretty disastrous. Without a moon, the Earth itself would naturally ‘wobble’ on its axis. Currently the Earth is at an angle of 23.4°, however this varies between a 22.1° and a 24.5° angle over a 41,000-year period. Without the Moon our planet would lose its stability and would tilt much more. This variation in tilt would affect global climates, seasons and even day lengths – there would be almost no consistency. An example of this is on Mars, a planet which only has two very tiny moons, each less than 27km across meaning their stabilizing effect is minimal; here, ice from the planet's poles has been observed at the equator! This is the same as the North Pole being moved to sub-Saharan Africa. If this kind of climate change were to happen on Earth it would be disastrous for almost every organism on the planet – especially those which can’t move. Life’s billions of years of evolution has lead every species to fill its own niche in an environment it is adapted to. Changing these environments so drastically could result in a mass extinction of several species. So, it’s probably best to leave the moon where it is for now – sorry werewolves!