So from time to time – out of the blue – Clay asks me questions like he thinks I know everything.  He says how much does the Earth weigh?  It’s not like asking how many in a dozen….or how many quarts in a gallon.  He asked me one I didn’t know, so that means I’ll have to look it up so the next time somebody asks me I’ll know.

But boy does it get complicated.  It’s not like you can put the Earth on a scale and weigh it.  So you have to use gravitational attraction that the Earth has for objects near it.  Isaac Newton came up with a formula that uses gravitational pull, force, and the distance between objects to measure mass.

I can’t really explain the formula because I’m not a physicist – I’m not even close to being a pharmacist – but if you take the radius of the Earth – something we know – and plug in all the other numbers in Newton’s formula you’ll come up with a figure something like 6 times 10 to the 24th power kilograms.  That would be 6 followed by 24 zeros in kilograms.  In pounds it would be 13 followed by 24 zeros.  Sounds a little on the light side to me

Some other things you should know about the Earth.  The surface and mantle are made up of 32% iron, 30% oxygen, 15% silicon, 14% magnesium, with the remaining 9% made up of other elements.  70% of the Earth’s surface is water, 30% is land.

Source: Science How Stuff Works