No moon? What an Apollo-ing notion! (forgive me)
In short: without a moon, things would get messy – although it may take a few thousand years for it to really sink in.
The moon does three important things on the Earth: it controls its tides, its rotation and its wobble.
By pulling at our oceans with its gravity, the moon gives us high tides. (The sun does a similar thing, but because it’s so much further away it doesn’t affect the tides as much.) So without the moon, tides would be less pronounced. Such a change wouldn’t sole-ly affect fishermen (get it?! Ok, I’ll stop now) – but also many animals that depend on changing tides to survive. Mass extinctions wouldn’t be great for the planet, but it wouldn’t cause the world to come to an end.
The moon also puts a damper on the Earth’s spinning speed and is causing it to slow down. This is called tidal friction. Thanks to the moon, our days are actually becoming gradually longer – they’d become shorter without it (only a couple of seconds every 100k years, though). Again, this wouldn’t be too much of a bother apart from having to change the leap years.
Losing the moon would also mean losing stability – the Earth wobbles as it orbits around the sun; the moon reduces this wobble. The physics behind this is a bit too complex to go into right now, but the result would be greater fluctuations in the Earth’s day lengths; there would be periods with no seasons, and times of seasonal weather extremes. Changes would still be quite gradual though, so we’d have some time before extreme climate change would put an end to our reign on Earth.
But more importantly, if we lost our moon, we’d have a tough time explaining to future generations what inspired werewolves, the Moon walk and songs like ‘Man in the Moon’. If we’d lost it a century ago, mankind would be “one large step” behind – though the Soviet Union and U.S. would have saved themselves a quarrel (and a lot of money).
Check out this documentary for a fuller story – including the likely origin of our moon.
To see what Hollywood makes of the matter, check out the 2013 blockbuster Oblivion.
Question from Mad Moules via Facebook
Answer by Isabel Hutchison