144. Gone Pear Shaped

The earth is officially ‘pear-shaped’ – not a round sphere as is commonly believed. Now do not get the wrong idea about this, it is not shaped like some huge interstellar fruit, that, while interesting would be plain ridiculous. It is barely pear-shaped, but pear-shaped enough.

Let us start at the beginning. We used to think the earth was flat, in the case of the Mayans we thought it had 4 corners and was placed on the back of a giant crocodile in a lily pond which in turn was on top of five different coloured trees. Then around 2200 years ago the Greeks, specifically Eratosthenes calculated that the earth was round and even made a fairly accurate estimation of its circumference.

Then comes Columbus. As you can tell, he did not discover that the world was round, it had been known for well over 1000 years before he was even born. He in fact set out to find a new and better trading route with parts of Asia, and failed. He did however succeed in another way by correctly believing the earth was shaped like the aforementioned cosmic fruit. In fact he claimed that he didn’t discover a better trading route to Asia because of the bulging part of the pear near the stalk. To be clear the earth does not have a stalk, but it is definitely a little pear shaped.

You see, the earth is irregular, some parts are rock, some are water and others are melted rock. This means it stretches when forces are applied to it. First thing, the earth spins,the equator spinning the fastest. This means more force on the equator and causes a bulge.

That’s the reason the earth is not round, now here comes the pearification. The earth is irregular remember, so it stretches bizarrely, this means it is not an oblate spheroid or a squashed sphere. Instead the bulge is not on the equator but just south. So now you know, the earth is pear-shaped, or Piriform if you want the correct adjective.

Further Reading

• The Shape of Planet Earth – a more mathematical explanation of this concept