How much does planet Earth weigh?

As far as weight goes, Earth is a pretty hefty celestial body. But exactly how heavy? And how does one measure something so massive? Find out in this podcast from HowStuffWorks.com.

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Episode Transcript

Speaker 1 (00:00):
Welcome to brain Stuff from house stuff works dot com
where smart happens. Hi Am Marshall Brain With today's question
how much does planet Earth weigh? It would be more
proper to ask what is the mass of Planet Earth?
The quick answer to that is approximately six times ten.
To them, it weighs a lot. The interesting sub question

(00:25):
is how did anyone figure that out? It's not like
the planet steps onto a scale each morning before it
takes a shower. It turns out that you can calculate
the mass of something if you know the magnitude of
its gravitational pull. Any two masses have a gravitational attraction
for one another. If you put two bowling balls near

(00:47):
each other, they will attract one another Gravitationally, the attraction
is extremely slight, but if your instruments are sensitive enough,
you can measure that gravitational attraction that two bowling balls
have on one an other. From that measurement, you could
determine the mass of the two objects. The same is
true for two golf balls, but the attraction is even

(01:08):
slighter because the amount of gravitational force depends on the
mass of the objects. Newton showed that for spherical objects
you can make the simplifying assumption that all of the
objects mass is concentrated at the center of the sphere.
He then came up with an equation that expresses the
gravitational attraction that two spherical objects have on one another.

(01:32):
It's force equals the gravitational constant times the mass of
the first object times the mass of the second object
over the distance between the two objects squared. Assume that
Earth is one of the masses and that a one
kilogram sphere is the other. The force between them is
nine point eight kilogram meters per second squared. We can

(01:55):
calculate this force by dropping the one ram sphere and
measuring acceleration that the Earth's gravitational field applies to it,
which is nine eight ms per second squared. The radius
of the Earth is six million, four hundred thousand meters.
If you plug all these values in and solve for
M one, you find that the mass of the Earth

(02:17):
is six times ten to Do you have any ideas
or suggestions for this podcast? If so, please send me
an email at podcast at how stuff works dot com.
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