From the posted website:

... Because we know the radius of the Earth, we can use the Law of Universal Gravitation to calculate the mass of the Earth in terms of the gravitational force on an object (its weight) at the Earth's surface, using the radius of the Earth as the distance. We also need the Constant of Proportionality in the Law of Universal Gravitation, G. This value was experimentally determined by Henry Cavendish in the 18th century to be the extremely small force of 6.67 x 10-11 Newtons between two objects weighing one kilogram each and separated by one meter. ...

Now isn't that interesting. I had seen this number before (actually just earlier today was the latest time) and lo and behold, and I am sure you will all just call this another co-incidence but the distance from The Earth to The Sun is 149,598,261. But this is 1.00000261 AU so the actual distance of one Astronomical Unit is 149,598,261 / 1.00000261 AU and this yields 149597870.55 and what do you suppose the reciprocal of this number is ... ?

1 / 149597870.55 = 6.6845871289907574527219938739796e-9

So not to suggest that I am a better man than Henry Cavendish but I would like to wager, 1 beer, that the actual value should be 6.68459 x 10 to the minus 11 and that this constant is directly proportional to the distance that The Earth is from The Sun and is not as suggested a universal constant at all.

Cheers
Don Barone

"There is nothing as impenetrable as a closed mind"
and ..." if everything is a coincidence what is the point of studying or measuring or analyzing anything ?" db