Grendel wrote on Apr 16^th, 2010 at 1:28pm:


How would you prove it, do you think?

Grendel wrote on Apr 16^th, 2010 at 1:41pm:


Yes,  it's very basic stuff. I could probably do it with a couple of long sticks, tape measures, spirit levels, and an assistant 1000km away in contact, on a mobile phone.

http://en.wikipedia.org/wiki/Eratosthenes

I've also played with LEO satellite tracking enough to understand how Keplerian elements work.

I could also measure atmospheric carbon dioxide quite easily and I could measure the infra-red absorbance of Carbon dioxide at 2.7, 4.3 and 15 micrometers. That's pretty basic stuff too.

Maybe that's why you take the view that the Earth is an oblate spheroid on faith, while I can understand the reasoning behind it.

You could say the same thing about Global Warming, I guess.

Ladies and gentlemen, mark this day in history. For 16 April 2010 shall forever be known as that day that Beo the Great proved that Eratosthenes was wrong. The following enlightened and immortal phrase shall forever be known as Grendel's Maxim: "Oh and BTW sticks wont prove Earth is an OBLATE SPHEROID".

This is a remarkable accomplishment, made all the more remarkable because of the facts that sticks can prove that the Earth is an oblate spheroid, did prove that the Earth is an oblate spheroid, and will continue to prove that the Earth is an oblate spheroid for as long as the sun will cast a shadow.

Asked for an opinion on this outstanding scientific achievement, the late Sir Isaac Newton is reported to have replied, "what a tosser".

Grendel wrote on Apr 16^th, 2010 at 7:39pm:


LOL.

You leave me almost speechless.

But I will grant you that you have a point. If you stick your fingers in your ears, shut your eyes and cover up your mouth then you will hear no evil, see no evil and speak no evil. (though you could probably sh1t some evil)

Apart from that, in such a position, you can't really prove anything. That is perfectly true.

So when you're prepared to emerge from your fetal position sucking your thumb, I'll explain a few things to you.

Trigonometry, beo.

Heard of it?

You don't even need sticks, let alone really long ones, and you certainly don't need a satellite. You just need to simultaneously compare, from two sufficiently distant observation points, the angle between the direction of the earth's gravitational force (as in down) and the direction towards the centre of the sun. Precise measurements and basic trigonometry will demonstrate that the results are inconsistent with a sphere, and consistent with an ellipsoid with the dimensions of the Earth.

An even easier way, measure the weight of an object of mass 1 kg at the equator and then again somewhere away from the equator (Melbourne would be good enough). The weights will be different, thus the distances to the centre of the Earth are significantly different. Hence, ellipsoid.

A third way, fire a projectile in a vacuum. Map the path and calculate the distance from the top of the arc to the nearest focus. Then calcuate the distance to the other focus (the other focus is at the centre of the earth). Do it again at a different distance from the equator. You will get a different distance to the centre of the Earth. Thus, ellipsoid.

You need some pretty good gear for the third method, but the first can probably be done with an surveyor's theodolite. The third just needs accurate scales, and adequate protection for the object to ensure it doesn't gain or lose any mass in transit.

Dude, any of the three methods above would be sufficient to define the precise shape of any planet, whether it's a spheroid, triangular prism or a giant pineapple.

You are proposing that it had neven been proven, nor was it known, that the Earth is an OBLATE SPHEROID until the 1950s. The size, shape and dimensions of the earth were well known in Newton's time. By 1798 we even knew it's mass.

Sort of assumed you'd know an oblate spheroid is an ellipsoid.