• Question: do you know how big the earth is in cm?

    Asked by lindseymerrygold to Christine, Edd, Jess, Nicolas, Zara on 12 Jun 2011.
    • Photo: Edward Codling

      Edward Codling answered on 10 Jun 2011:

      Not off the top of my head!

      However, according to Wikipedia the Earth’s circumference at the equator is 40,075.017km. There are 1000 metres in a kilometre and 100cm in a metre, so the Earth’s circumference in cm would be:

      40,075.017 x 1000 x 100 = 4,007,501,700 cm

      (i.e. just over 4 billion cm)

    • Photo: Zara Gladman

      Zara Gladman answered on 11 Jun 2011:

      I left this question to the mathematician! If you’re interested in scale, check this out: http://www.primaxstudio.com/stuff/scale_of_universe/ so cool! although it makes me feel a bit dizzy.

    • Photo: Jessica Chu

      Jessica Chu answered on 12 Jun 2011:

      Awesome!

      I am only 160 cm tall so I will need 25,046,886 of me lined head-to-toe and arms spread out to hug the world!!!

    • Photo: Christine Switzer

      Christine Switzer answered on 12 Jun 2011:

      There is a straighforward answer to this question and then there’s my answer: it depends entirely how you measure it. Let’s take Great Britain as an example. How far is it around Britain? If you take a map where Britain is small, like a model globe for example, and measure all of the way around it, you will get an answer. If you take a map that zooms in a bit, you will see that there are a number of places that you missed the first time. If you zoom in again, you will find more nooks and crannies that you missed the second time. Each time you zoom in, you will find more spots that you missed and your measurement will increase. You can apply the same approach to measuring the globe. That 4 billion centimetres would probably work ok for somewhere pretty flat with lots of ocean. It probably would not be nearly enough to get you around a circumference that includes the Himalayas. You might wonder how far we can zoom in and the honest answer is that we don’t know yet! Our microscopes are getting better and better, and there is still a lot more room for improvement.

    • Photo: Nicolas Biber

      Nicolas Biber answered on 12 Jun 2011:

      An interesting question that made me want to take it further (this happens very often in science :)). So we have a circumference of four billion centimetres. I wonder what the volume might be in cubic centimetres. This would be (4,000,000 cm/2π)^3 * 4/3 * π =1,080,759,292,184,940,000,000,000,000 cm^3, or 1,080,759,292,184,940,000,000,000 liters, or about 2,000,000,000,000,000,000,000,000 pints … that is about one billion billion billion cubic centimetres, or one thousand billion cubic kilometres … correct me if i’m wrong, I might have lost it at some point along the way … the earth is mindbogglingly big, and it’s surprising that nobody has come up with a more convenient unit to describe the size.
      Sizes only make sense to us if we have anything to relate them to, but it is very difficult to keep track of all the zeroes in such a big number, and even if we say that the earth is as big as 650,000,000,000,000,000,000,000 water bottles it does not give us an understanding of the size. Also the Earth is only a tiny cluster of matter in a very large space.

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