I recently read something that said scientists have calculated that the earth weighs “x” tons. My question is “in relation to what?”. Where is this planet being weighed, in space? I was always taught that things were weightless in space. I understand the earth has mass, but relative to where it’s located (in space), shouldn’t the earth be weightless??
I assume that the “tons” to which they are referring are METRIC tons. That translates into kilograms, which is a mass, not a weight. Mass is not dependent on a gravitational pull.
This can be done quite easily.
Just take your basic bathroom scale outside, and turn it upside down.
The entire earth is now resting on it.
Flip it over real quick, and you have a pretty good idea of the earth’s weight.
The late Isaac Asimov agreed with you. He wrote about this in his article titled “The Man Who Massed The Earth.” It’s about Henry Cavendish who in 1798 measured the gravitational attraction between masses in his laboratory and thereby determined the universal constant of gravitation.
At the end of his article, Asimov reasoned that since the earth is in free fall relative to the sun (and every other celestial body), it’s weightless.
Cecil mentions the “weight” of the earth in this article: http://www.straightdope.com/classics/a3_355.html
The “weight” of the earth is roughly 6 sextillion, 588 quintillion tons. Cavendish determined the mass of the earth in kilograms, presumably. Converting it to tons is technically incorrect, but few people know or care about the essential difference. You can consider that “Ton” here is just shorthand for saying “the equivalent mass that weighs one ton on the surface of the earth” or “ton-mass-equivalent.”
Mjollnir, you’ve got it all wrong… that’s not how you go about weighing the earth. We’ve gone through this before. Here is a link to our discussion on how to properly weigh the earth. Thank you for your attention.