• Question: How much dose the earth way ??

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      Asked by anon-285693 on 5 Mar 2021.
      • Photo: Miriam O'Duill

        Miriam O'Duill answered on 5 Mar 2021:

        The earth weighs about 6 trillion trillion kilograms (6,000,000, 000,000,000,000,000,000 kg).

        You obviously can’t just put the earth on scales and weigh it. So scientists used gravity to find out the earth’s mass. Newton realised that when an apple falls out of a tree, it falls straight to the ground (never sideways or even up towards the sky) because it’s being pulled down by the earth’s gravitational force. He also figured out that the strength of that force depends on the apple’s mass AND the earth’s mass. So, if you know how much the apple weighs, you can calculate how much the earth weighs. (Newton figured all of this out during a pandemic, when his school shut down and he was isolating at his family’s home in Lincolnshire.)

      • Photo: Martin McCoustra

        Martin McCoustra answered on 5 Mar 2021:

        I don’t know off hand but Google is a wonderful source of information like this… It told me 5,972,000,000,000,000,000,000,000 kg!

      • Photo: Jesko Koehnke

        Jesko Koehnke answered on 5 Mar 2021:

        You need to be very careful here, because weight and mass are often confused. Mass is the sum of all the particles that make up an object, while weight is the force of gravity on that object. So the mass will not change if you move the object from earth to the moon for example, but the object will weigh about 1/6th, because the moon has less mass and thus the object experiences less gravity.

        So for earth, we can estimate what mass it has, and that is about 6 trillion kg. But the weight of earth would be measured by the force of the sun’s gravity on earth’s mass, and working that out gets very complicated.

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