What would hap­pen if we lost our moon? Asked via Face­book

Guru Magazine - - Ask A Guru -

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, caus­ing it to ever-so-slightly slow down. This is called tidal fric­tion and, thanks to the moon, our days are ac­tu­ally be­com­ing grad­u­ally longer. With­out our moon, days would grad­u­ally be­come shorter. This wouldn’t be too much of a bother though, as we would lose only a cou­ple of sec­onds ev­ery 100,000 years. Los­ing the moon would mean los­ing the Earth’s sta­bil­ity: our planet wob­bles as it or­bits around the sun and the moon re­duces this wob­ble. The physics be­hind this is a bit too com­plex to go into, 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.

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