HAPPY NEW YEAR! Here’s Mathematician KP Hart’s Math Question and Answer for Monday, January 4th!

This week’s question was posed in the Dutch Science Agenda: Is the Earth round or flat or oval? Or none of these? In the Koran, Earth is described as flat.

Earth is round or flat or oval. How do you measure that? Can the Earth be measured or is that fact or fables? Scientific? How is it that Earth is called Ball-shaped? I think the Earth is endless without a shape. If the Earth were turning would the direction of Qibla- Kabaa to Mecca change too? And the people, seas and road would shift direction?

There is a nice Wikipedia page about the shape of the Earth. You can read there that it is not quite a ball: around the equator the radius is 21 km larger than at the poles. Compared to the Earth’s radius of more than 6000 km, that is very little. So little that if you were to scale Earth down to a ball with a radius of 6 cm that difference would be only one-thirtieth of a millimeter. The same goes for mountains like Mount Everest and deep points like the Mariana Trench. You would not be able to feel them.

Measuring that Earth is not flat can be done in the following (albeit not very practical) way. Take a large triangle, say with vertices in Amsterdam, Berlin and Madrid. You will see that the sum of the angles is more than 180 degrees, or π. If the Earth were flat then that sum would always be exactly 180 degrees.

Although Earth rotates about its axis the mutual directions do not change: if you sit at the North Pole with your face towards Mecca (straight South, along the meridian) then you will rotate along with the Earth and your face will always be in the direction of Mecca.

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Read all of KP Harts math questions here!

About Dutch Mathematician KP Hart: In the beginning of this year the Dutch government opened a website, The Dutch Science Agenda, where everyone could post questions that they thought were of scientific interest. This was an attempt to involve the whole country in determining what the Dutch science agenda should be in the coming years.

I looked through the questions and searched for terms like `mathematics’, `infinity’ … to see what mathematical questions there were and I noticed various questions that already have answers (and have had for a long time). On a whim I decided to post answers to those questions, in Dutch. For your edification I will translate these posts into English.