[FE-Experiments]

none

[Thork]

I did some experiments that show that there is a case for an earth that is not a sphere. It is however not easy to prove it.

Some people are convinced that when you measure the shadow with a stick (same length) at three different locations at the same time, you can figure out the shape of the earth.
I don't have much knowledge about geometry/trigonometry.

Do you think that is true? Would this test show that the earth is a ball or not a ball without assumptions?

Is there another geometric/trigonometric test you can do on the ground that can prove what the shape is of the earth without assumptions?

Sticks is hard. They need to be a looooooonnnnnnnnnngggggggggg way apart and the sun moves. Not only hour by hour, but its azimuth changes day by day. Pain to do by yourself.

The easiest is to find a large body of water without waves, set a powerful laser pen or similar up about 6 inches above the water and see if you can get it to focus 6 inches above the water 1 mile away. If you get a little red dot (and you will) ... the earth is flat.

http://www.ringbell.co.uk/info/hdist.htm

[LRP]

What we need is say 100 volunteers from different parts of the world who have access to a spot where a 1.0m long (39.3inches) pole can be positioned vertically. These volunteers would need  to give their exact location on the Earth including elevation above sea level  to the nearest mile and measure the length and direction  of their shadow at   say    06.00  09.00,  12.00  15.00 and 18.OO and 21.00 hours GMT on two or three specified days.  Their readings would then be input into a computer which would work out the elevation and position  of the Sun at the specified times and the theoretical length and directions of the shadows based on a flat earth and a round earth.  The computer would compare the measured values with the theoretical values and  I think should be able to tell us which is the best fit.   Someone who is competent with the maths and computers would have to be found and it could  make a good project for an undergraduate in a University.  Just an idea     

[Thork]

0.9 miles. Which is why I suggested a mile. But make it three if you have enough of a stretch of water and a powerful enough laser.